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Behanova M, Medibach A, Haschka J, Kraus D, Raimann A, Mindler GT, Zwerina J, Kocijan R. Health-related quality of life and fatigue in adult rare bone disease patients: A cross-sectional study from Austria. Bone 2024; 181:117034. [PMID: 38311305 DOI: 10.1016/j.bone.2024.117034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 01/25/2024] [Accepted: 01/31/2024] [Indexed: 02/10/2024]
Abstract
OBJECTIVES To assess physical and mental health domains of health related quality of life (HRQoL) as well as fatigue in rare bone disease (RBD) patients and to compare to patients with osteoporosis (OPO) and healthy controls (CTRL) without known bone diseases and to study associations of Fatique Severity Scale (FSS) with eight domains of HRQoL. METHODS Monocentric, cross-sectional study carried out between 2020 and 2022 in a hospital affiliated with the Vienna Bone and Growth Center (European Reference Network Center for Rare Bone Disease) in Vienna, Austria. The study comprised three types of RBD: Osteogenesis imperfecta, Hypophosphatasia and X-linked Hypophosphatemia. Fatigue was assessed by FSS. The higher score indicates more fatigue severity. HRQoL was assessed by Short-Form Health Survey (SF-36 v2). Physical component (PCS) and mental component summary scores (MCS) were calculated and normalised to a general population. A higher score indicates better HRQoL. Age-adjusted ANCOVA was used to assess differences in PCS and MCS between groups. Spearman correlation was used for associations of FSS with eight domains of HRQoL. RESULTS Study comprised 50 RBD patients [Mean age (SD) 48.8 (±15.9), 26 % male], 51 OPO patients [66.6 (±10.0), 9.8 % male] and 52 controls [50.8 (±16.3), 26.9 % male]. RBD patients had significantly higher mean age-adjusted FSS (3.5, 95 % CI 3.1-4.0) than controls (2.6, 95 % CI 2.2-3.0, p = 0.008), but not in comparison to osteoporotic patients 2.6 (95 % CI 2.2-3.0, p = 0.69). Diminished age-adjusted PCS of HRQoL was observed in RBD patients with a mean score of 37.1 (95 % CI 33.4-40.8), whereas their MCS of 50.1 (95 % CI 46.6-53.7) was comparable to controls (52.9, 95 % CI 49.8-56.0) and osteoporotic patients (50.2, 95 % CI 45.4-54.9). FSS score was negatively correlated with physical and mental component in RBD (ρ = -0.37, p < 0.05 and ρ = -0.54, p < 0.01, respectively) and OPO patients (ρ = -0.37, p < 0.05 and ρ = -0.35, p < 0.01, respectively). CONCLUSIONS The HRQoL in adult patients with rare bone diseases is lower than compared to osteoporotic and control group in this Austrian population. Fatigue has significant negative impact on HRQoL and it is important to address it when meeting with RBD patients in clinical practice.
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Affiliation(s)
- Martina Behanova
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA, Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria
| | - Amadea Medibach
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA, Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria; Sigmund Freud University Vienna, School of Medicine, Metabolic Bone Diseases Unit, Vienna, Austria
| | - Judith Haschka
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA, Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria; Vienna Bone and Growth Center, Vienna, Austria
| | - Daniel Kraus
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA, Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria
| | - Adalbert Raimann
- Vienna Bone and Growth Center, Vienna, Austria; Department of Pediatrics and Adolescent Medicine, Division of Pediatric Pulmonology, Allergology and Endocrinology, Medical University of Vienna, Vienna, Austria
| | - Gabriel T Mindler
- Vienna Bone and Growth Center, Vienna, Austria; Department of Pediatric Orthopaedics, Orthopaedic Hospital Speising, Vienna, Austria
| | - Jochen Zwerina
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA, Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria; Vienna Bone and Growth Center, Vienna, Austria
| | - Roland Kocijan
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA, Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria; Sigmund Freud University Vienna, School of Medicine, Metabolic Bone Diseases Unit, Vienna, Austria; Vienna Bone and Growth Center, Vienna, Austria.
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Zervou Z, Plooij R, van Velsen EFS, Timmermans RGM, Demirdas S, Zillikens MC. Impressive clinical improvement and disappearance of neuropathic pain in an adult patient with hypophosphatasia treated with asfotase alfa. Eur J Med Genet 2024; 68:104915. [PMID: 38325645 DOI: 10.1016/j.ejmg.2024.104915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 01/16/2024] [Accepted: 01/28/2024] [Indexed: 02/09/2024]
Abstract
Hypophosphatasia (HPP) is a rare disorder, resulting from loss-of-function variants of the ALPL gene encoding non-tissue specific alkaline phosphatase (TNSALP). Presentation varies largely, with increased severity usually occurring with earlier disease onset. Here we describe the clinical improvement of a 57-year-old woman with childhood onset HPP, after initiating treatment with asfotase alfa (Strensiq®). This was started because of the rapid and progressive radiological deterioration of bone structure after placement of nails in both upper legs for spontaneous atypical femur fracture (AFF) - like fractures. Initiation of treatment, not only resulted in stabilization of bone structure on X-rays, but within a few weeks there was a dramatic reduction of burning pain sensations in the lower legs, attributed in retrospect to neuropathic pain, and also almost complete disappearance of headaches. Additionally, unhealed metatarsal fractures finally healed after almost 10 years. Drug efficacy was further evaluated through -quality of life questionnaires and multiple tests conducted by the physiotherapist, and showed clear improvements. Within 3 months after starting asfotase alfa, the patient was able to carry out her daily tasks indoors without relying on a walker and even started electric bike rides for 20 km/day. In conclusion, treatment with asfotase alfa, halted rapid radiological bone deterioration after bilateral intramedullary femoral pen placement and strongly increased quality of life, marked by rapid disappearance of neuropathic pain, reduction in headaches and musculoskeletal pains, and enhanced muscle strength and mobility. The quick and almost complete disappearance of neuropathic pain and headache suggests a relation with disturbed levels of metabolites in HPP.
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Affiliation(s)
- Zografia Zervou
- Erasmus MC Bone Center, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Roel Plooij
- Erasmus MC, Department of Rehabilitation Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Evert F S van Velsen
- Erasmus MC Bone Center, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Remco G M Timmermans
- Erasmus MC, Department of Rehabilitation Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Serwet Demirdas
- Department of Clinical Genetics, Sophia Children's Hospital, Erasmus Medical Centre, Erasmus University, Rotterdam, the Netherlands
| | - M Carola Zillikens
- Erasmus MC Bone Center, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands.
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Khan AA, Brandi ML, Rush ET, Ali DS, Al-Alwani H, Almonaei K, Alsarraf F, Bacrot S, Dahir KM, Dandurand K, Deal C, Ferrari SL, Giusti F, Guyatt G, Hatcher E, Ing SW, Javaid MK, Khan S, Kocijan R, Linglart A, M'Hiri I, Marini F, Nunes ME, Rockman-Greenberg C, Roux C, Seefried L, Simmons JH, Starling SR, Ward LM, Yao L, Brignardello-Petersen R, Lewiecki EM. Hypophosphatasia diagnosis: current state of the art and proposed diagnostic criteria for children and adults. Osteoporos Int 2024; 35:431-438. [PMID: 37982857 PMCID: PMC10866785 DOI: 10.1007/s00198-023-06844-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 06/23/2023] [Indexed: 11/21/2023]
Abstract
BACKGROUND This manuscript provides a summary of the current evidence to support the criteria for diagnosing a child or adult with hypophosphatasia (HPP). The diagnosis of HPP is made on the basis of integrating clinical features, laboratory profile, radiographic features of the condition, and DNA analysis identifying the presence of a pathogenic variant of the tissue nonspecific alkaline phosphatase gene (ALPL). Often, the diagnosis of HPP is significantly delayed in both adults and children, and updated diagnostic criteria are required to keep pace with our evolving understanding regarding the relationship between ALPL genotype and associated HPP clinical features. METHODS An International Working Group (IWG) on HPP was formed, comprised of a multidisciplinary team of experts from Europe and North America with expertise in the diagnosis and management of patients with HPP. Methodologists (Romina Brignardello-Petersen and Gordon Guyatt) and their team supported the IWG and conducted systematic reviews following the GRADE methodology, and this provided the basis for the recommendations. RESULTS The IWG completed systematic reviews of the literature, including case reports and expert opinion papers describing the phenotype of patients with HPP. The published data are largely retrospective and include a relatively small number of patients with this rare condition. It is anticipated that further knowledge will lead to improvement in the quality of genotype-phenotype reporting in this condition. CONCLUSION Following consensus meetings, agreement was reached regarding the major and minor criteria that can assist in establishing a clinical diagnosis of HPP in adults and children.
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Affiliation(s)
- Aliya A Khan
- Division of Endocrinology and Metabolism, McMaster University, Hamilton, Canada.
| | - Maria Luisa Brandi
- F.I.R.M.O. Italian Foundation for the Research On Bone Diseases, Florence, Italy
- Donatello Bone Clinic, Villa Donatello Hospital, Florence, Italy
| | - Eric T Rush
- Division of Clinical Genetics, Children's Mercy Kansas City, Kansas City, MO, USA
- Division of Endocrinology, Metabolism, Osteoporosis and Genetics, Department of Internal Medicine, University of Kansas School of Medicine, Kansas City, KS, USA
- Department of Pediatrics, University of Missouri-Kansas City School of Medicine, Kansas City, MO, USA
| | - Dalal S Ali
- Division of Endocrinology and Metabolism, McMaster University, Hamilton, Canada
| | - Hatim Al-Alwani
- Division of Endocrinology and Metabolism, McMaster University, Hamilton, Canada
| | - Khulod Almonaei
- Division of Endocrinology and Metabolism, McMaster University, Hamilton, Canada
| | - Farah Alsarraf
- Division of Endocrinology and Metabolism, McMaster University, Hamilton, Canada
| | - Severine Bacrot
- Department of Genetics, Centre Hospitalier de Versailles, Hôpital André Mignot, Versailles, France
| | - Kathryn M Dahir
- Division of Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Karel Dandurand
- Department of Medicine, Endocrinology and Metabolism, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Chad Deal
- Center for Osteoporosis and Metabolic Bone Disease, Department of Rheumatology, The Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Serge Livio Ferrari
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland
| | - Francesca Giusti
- Donatello Bone Clinic, Villa Donatello Hospital, Florence, Italy
| | - Gordon Guyatt
- Department of Health Research Methods, Evidence and Impact at McMaster University, Hamilton, Canada
| | - Erin Hatcher
- Neuromuscular Clinic, McMaster University Medical Centre, Hamilton Health Sciences, Hamilton, Canada
| | - Steven W Ing
- Division of Endocrinology, Diabetes & Metabolism, Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Muhammad Kassim Javaid
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
| | - Sarah Khan
- Bone Research and Education Centre, Oakville, ON, Canada
| | - Roland Kocijan
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA, Trauma Centre Meidling, 1St Medical Department Hanusch Hospital, 1140, Vienna, Austria
| | - Agnes Linglart
- APHP, Bicêtre Paris-Sud, UniversityParis Sud, Paris-Saclay, Le Kremlin Bicêtre, Paris, France
| | - Iman M'Hiri
- Bone Research and Education Centre, Oakville, ON, Canada
| | - Francesca Marini
- F.I.R.M.O. Italian Foundation for the Research On Bone Diseases, Florence, Italy
| | - Mark E Nunes
- Division of Medical Genetics and Metabolism, Valley Children's HealthCare, Madera, CA, USA
| | | | - Christian Roux
- INSERM CRESS UMR 1153, Paris, France
- Université Paris-Cité, Department of Rheumatology, APHP-Centre, Cochin Hospital, Paris, France
| | - Lothar Seefried
- Musculoskeletal Center Wuerzburg, University of Würzburg, Würzburg, Germany
| | - Jill H Simmons
- Division of Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Susan R Starling
- Division of Clinical Genetics, Children's Mercy Kansas City, Kansas City, MO, USA
| | - Leanne M Ward
- Children's Hospital of Eastern Ontario, Department of Pediatrics, University of Ottawa, Ottawa, ON, Canada
| | - Liang Yao
- Department of Health Research Methods, Evidence and Impact at McMaster University, Hamilton, Canada
| | | | - E Michael Lewiecki
- New Mexico Clinical Research & Osteoporosis Center, Albuquerque, NM, USA
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Baroncelli GI, Carlucci G, Freri E, Giuca MR, Guarnieri V, Navarra G, Toschi B, Mora S. The diagnosis of hypophosphatasia in children as a multidisciplinary effort: an expert opinion. J Endocrinol Invest 2024; 47:739-747. [PMID: 37752373 PMCID: PMC10904512 DOI: 10.1007/s40618-023-02199-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 09/12/2023] [Indexed: 09/28/2023]
Abstract
Hypophosphatasia (HPP) is a rare genetic disorder in which pathogenic variants of the ALPL gene lead to a marked decrease of tissue non-specific alkaline phosphatase (TNSALP) activity. Although HPP is a systemic disorder, its clinical manifestations are more evident on bones, teeth, muscle and central nervous system. The clinical spectrum ranges from severe forms with extreme skeletal deformities, respiratory impairment, seizures, to very mild forms with onset in late adulthood and few clinical signs. The diagnosis can be suspected by measurement of TNSALP activity, but the insufficient awareness among health professionals and the lack of official guidelines are responsible for delayed diagnosis in children with HPP. The purpose of the current document is to provide an expert opinion directed at optimizing the diagnostic pathway of pediatric HPP. From April to December 2022, a multidisciplinary working group of 6 experts including two pediatric endocrinologists, a pediatric neurologist, a pediatric odontologist, a clinical geneticist, and a molecular biologist gathered in a series of periodic meetings to discuss the main issues related to the diagnosis of HPP in children and formalize an Expert Opinion statement. The experts agreed on a diagnostic trail that begins with the recognition of specific clinical signs, leading to biochemical analyses of TNSALP activity and vitamin B6 serum concentration. Very important are the neurological and dental manifestation of the disease that should be thoroughly investigated. The evaluation of TNSALP activity must consider sex and age variability and low activity must be persistent. Repeated blood measurements are thus necessary. The molecular analysis is then mandatory to confirm the diagnosis and for genetic counseling.
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Affiliation(s)
- G I Baroncelli
- Pediatric and Adolescent Endocrinology, Division of Pediatrics, Department of Obstetrics, Gynecology and Pediatrics, University Hospital, Pisa, Italy
| | - G Carlucci
- OPT S.P.A., Soluzioni Per Il Mondo Healthcare, Milan, Italy
| | - E Freri
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - M R Giuca
- Unit of Pediatric Dentistry, Department of Surgical Medical Molecular Pathology and Critical Area, Dental and Oral Surgery Clinic, University of Pisa, Pisa, Italy
| | - V Guarnieri
- Division of Medical Genetics, Fondazione IRCCS Casa Sollievo della Sofferenza, Foggia, Italy
| | - G Navarra
- OPT S.P.A., Soluzioni Per Il Mondo Healthcare, Milan, Italy
| | - B Toschi
- Section of Medical Genetics, Department of Medical and Oncological Area, University Hospital, Pisa, Italy
| | - S Mora
- Laboratory of Pediatric Endocrinology, Department of Pediatrics, IRCCS San Raffaele Hospital, Milan, Italy.
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González-Cejudo T, Villa-Suárez JM, Ferrer-Millán M, Andújar-Vera F, Contreras-Bolívar V, Andreo-López MC, Gómez-Vida JM, Martínez-Heredia L, González-Salvatierra S, de Haro Muñoz T, García-Fontana C, Muñoz-Torres M, García-Fontana B. Mild hypophosphatasia may be twice as prevalent as previously estimated: an effective clinical algorithm to detect undiagnosed cases. Clin Chem Lab Med 2024; 62:128-137. [PMID: 37440753 DOI: 10.1515/cclm-2023-0427] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 07/04/2023] [Indexed: 07/15/2023]
Abstract
OBJECTIVES Since the prevalence of hypophosphatasia (HPP), a rare genetic disease, seems to be underestimated in clinical practice, in this study, a new diagnostic algorithm to identify missed cases of HPP was developed and implemented. METHODS Analytical determinations recorded in the Clinical Analysis Unit of the Hospital Universitario Clínico San Cecilio in the period June 2018 - December 2020 were reviewed. A new clinical algorithm to detect HPP-misdiagnosed cases was used including the following steps: confirmation of persistent hypophosphatasemia, exclusion of secondary causes of hypophosphatasemia, determination of serum pyridoxal-5'-phosphate (PLP) and genetic study of ALPL gene. RESULTS Twenty-four subjects were selected to participate in the study and genetic testing was carried out in 20 of them following clinical algorithm criteria. Eighty percent of patients was misdiagnosed with HPP following the current standard clinical practice. Extrapolating these results to the current Spanish population means that there could be up to 27,177 cases of undiagnosed HPP in Spain. In addition, we found a substantial proportion of HPP patients affected by other comorbidities, such as autoimmune diseases (∼40 %). CONCLUSIONS This new algorithm was effective in detecting previously undiagnosed cases of HPP, which appears to be twice as prevalent as previously estimated for the European population. In the near future, our algorithm could be globally applied routinely in clinical practice to minimize the underdiagnosis of HPP. Additionally, some relevant findings, such as the high prevalence of autoimmune diseases in HPP-affected patients, should be investigated to better characterize this disorder.
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Affiliation(s)
- Trinidad González-Cejudo
- Clinical Analysis Unit, University Hospital Clínico San Cecilio, Granada, Spain
- Department of Medicine, University of Granada, Granada, Spain
| | | | - María Ferrer-Millán
- Instituto de Investigación Biosanitaria de Granada (ibs. GRANADA), Granada, Spain
| | - Francisco Andújar-Vera
- Department of Computer Science and Artificial Intelligence, University of Granada, Granada, Spain
- CIBER on Frailty and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- Andalusian Research Institute in Data Science and Computational Intelligence (DaSCI Institute), Granada, Spain
| | - Victoria Contreras-Bolívar
- Instituto de Investigación Biosanitaria de Granada (ibs. GRANADA), Granada, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, Granada, Spain
| | | | | | | | - Sheila González-Salvatierra
- Instituto de Investigación Biosanitaria de Granada (ibs. GRANADA), Granada, Spain
- Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, Granada, Spain
| | - Tomás de Haro Muñoz
- Clinical Analysis Unit, University Hospital Clínico San Cecilio, Granada, Spain
| | - Cristina García-Fontana
- Instituto de Investigación Biosanitaria de Granada (ibs. GRANADA), Granada, Spain
- CIBER on Frailty and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, Granada, Spain
| | - Manuel Muñoz-Torres
- Department of Medicine, University of Granada, Granada, Spain
- Instituto de Investigación Biosanitaria de Granada (ibs. GRANADA), Granada, Spain
- CIBER on Frailty and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, Granada, Spain
| | - Beatriz García-Fontana
- Instituto de Investigación Biosanitaria de Granada (ibs. GRANADA), Granada, Spain
- CIBER on Frailty and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- Department of Cell Biology, University of Granada, Granada, Spain
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Martínez-Heredia L, Muñoz-Torres M, Sanabria-de la Torre R, Jiménez-Ortas Á, Andújar-Vera F, González-Cejudo T, Contreras-Bolívar V, González-Salvatierra S, Gómez-Vida JM, García-Fontana C, García-Fontana B. Systemic effects of hypophosphatasia characterization of two novel variants in the ALPL gene. Front Endocrinol (Lausanne) 2024; 14:1320516. [PMID: 38234425 PMCID: PMC10792043 DOI: 10.3389/fendo.2023.1320516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 12/04/2023] [Indexed: 01/19/2024] Open
Abstract
Introduction Hypophosphatasia (HPP) is an inborn metabolic error caused by mutations in the ALPL gene encoding tissue non-specific alkaline phosphatase (TNSALP) and leading to decreased alkaline phosphatase (ALP) activity. Although the main characteristic of this disease is bone involvement, it presents a great genetic and clinical variability, which makes it a systemic disease. Methods Patients were recruited based on biochemical assessments. Diagnosis was made by measuring serum ALP and pyridoxal 5-phosphate levels and finally by Sanger sequencing of the ALPL gene from peripheral blood mononuclear cells. Characterization of the new variants was performed by transfection of the variants into HEK293T cells, where ALP activity and cellular localization were measured by flow cytometry. The dominant negative effect was analyzed by co-transfection of each variant with the wild-type gene, measuring ALP activity and analyzing cellular localization by flow cytometry. Results Two previously undescribed variants were found in the ALPL gene: leucine 6 to serine missense mutation (c.17T>C, L6S) affecting the signal peptide and threonine 167 deletion (c.498_500delCAC, T167del) affecting the vicinity of the active site. These mutations lead mainly to non-pathognomonic symptoms of HPP. Structural prediction and modeling tools indicated the affected residues as critical residues with important roles in protein structure and function. In vitro results demonstrated low TNSALP activity and a dominant negative effect in both mutations. The results of the characterization of these variants suggest that the pleiotropic role of TNSALP could be involved in the systemic effects observed in these patients highlighting digestive and autoimmune disorders associated with TNSALP dysfunction. Conclusions The two new mutations have been classified as pathogenic. At the clinical level, this study suggests that both mutations not only lead to pathognomonic symptoms of the disease, but may also play a role at the systemic level.
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Affiliation(s)
| | - Manuel Muñoz-Torres
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, Granada, Spain
- Department of Medicine, University of Granada, Granada, Spain
- Biomedical Research Network in Fragility and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - Raquel Sanabria-de la Torre
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Department of Biochemistry, Molecular Biology III and Immunology, University of Granada, Granada, Spain
| | - Ángela Jiménez-Ortas
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Department of Biochemistry and Molecular Biology II, University of Granada, Granada, Spain
| | - Francisco Andújar-Vera
- Department of Computer Science and Artificial Intelligence, University of Granada, Granada, Spain
- Andalusian Research Institute in Data Science and Computational Intelligence (DaSCI Institute), Granada, Spain
- Bioinformatic Service, Instituto de Investigación Biosanitaria de Granada, Granada, Spain
| | - Trinidad González-Cejudo
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Clinical Analysis Unit, University Hospital Clínico San Cecilio, Granada, Spain
| | | | - Sheila González-Salvatierra
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, Granada, Spain
- Department of Medicine, University of Granada, Granada, Spain
| | | | - Cristina García-Fontana
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, Granada, Spain
- Biomedical Research Network in Fragility and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - Beatriz García-Fontana
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, Granada, Spain
- Biomedical Research Network in Fragility and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- Department of Cell Biology, University of Granada, Granada, Spain
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7
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Rush E, Brandi ML, Khan A, Ali DS, Al-Alwani H, Almonaei K, Alsarraf F, Bacrot S, Dahir KM, Dandurand K, Deal C, Ferrari SL, Giusti F, Guyatt G, Hatcher E, Ing SW, Javaid MK, Khan S, Kocijan R, Lewiecki EM, Linglart A, M'Hiri I, Marini F, Nunes ME, Rockman-Greenberg C, Roux C, Seefried L, Starling SR, Ward L, Yao L, Brignardello-Petersen R, Simmons JH. Proposed diagnostic criteria for the diagnosis of hypophosphatasia in children and adolescents: results from the HPP International Working Group. Osteoporos Int 2024; 35:1-10. [PMID: 37982855 PMCID: PMC10786745 DOI: 10.1007/s00198-023-06843-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 06/23/2023] [Indexed: 11/21/2023]
Abstract
Hypophosphatasia (HPP) is a rare inborn error of metabolism that presents variably in both age of onset and severity. HPP is caused by pathogenic variants in the ALPL gene, resulting in low activity of tissue nonspecific alkaline phosphatase (TNSALP). Patients with HPP tend have a similar pattern of elevation of natural substrates that can be used to aid in diagnosis. No formal diagnostic guidelines currently exist for the diagnosis of this condition in children, adolescents, or adults. The International HPP Working Group is a comprised of a multidisciplinary team of experts from Europe and North America who have expertise in the diagnosis and management of patients with HPP. This group reviewed 93 papers through a Medline, Medline In-Process, and Embase search for the terms "HPP" and "hypophosphatasia" between 2005 and 2020 and that explicitly address either the diagnosis of HPP in children, clinical manifestations of HPP in children, or both. Two reviewers independently evaluated each full-text publication for eligibility and studies were included if they were narrative reviews or case series/reports that concerned diagnosis of pediatric HPP or included clinical aspects of patients diagnosed with HPP. This review focused on 15 initial clinical manifestations that were selected by a group of clinical experts.The highest agreement in included literature was for pathogenic or likely pathogenic ALPL variant, elevation of natural substrates, and early loss of primary teeth. The highest prevalence was similar, including these same three parameters and including decreased bone mineral density. Additional parameters had less agreement and were less prevalent. These were organized into three major and six minor criteria, with diagnosis of HPP being made when two major or one major and two minor criteria are present.
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Affiliation(s)
- Eric Rush
- Division of Clinical Genetics, Children's Mercy Kansas City, 2401 Gillham Road, Kansas City, MO, USA.
- Department of Pediatrics, University of Missouri - Kansas City School of Medicine, 2401 Gillham Road, Kansas City, MO, USA.
- Division of Endocrinology, Metabolism, Osteoporosis, and Genetics, Department of Internal Medicine, University of Kansas School of Medicine, Kansas City, KS, USA.
| | - Maria Luisa Brandi
- F.I.R.M.O. Italian Foundation for the Research on Bone Diseases, Florence, Italy
- Donatello Bone Clinic, Villa Donatello Hospital, Florence, Italy
| | - Aliya Khan
- Division of Endocrinology and Metabolism, McMaster University, Hamilton, Canada
| | - Dalal S Ali
- Division of Endocrinology and Metabolism, McMaster University, Hamilton, Canada
| | - Hatim Al-Alwani
- Division of Endocrinology and Metabolism, McMaster University, Hamilton, Canada
| | - Khulod Almonaei
- Division of Endocrinology and Metabolism, McMaster University, Hamilton, Canada
| | - Farah Alsarraf
- Division of Endocrinology and Metabolism, McMaster University, Hamilton, Canada
| | - Severine Bacrot
- Department of Genetics, Centre Hospitalier de Versailles, Hôpital André Mignot, Versailles, France
| | - Kathryn M Dahir
- Division of Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Karel Dandurand
- Department of Medicine, Endocrinology and Metabolism, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Chad Deal
- Center for Osteoporosis and Metabolic Bone Disease, Department of Rheumatology, The Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Serge Livio Ferrari
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland
| | - Francesca Giusti
- Donatello Bone Clinic, Villa Donatello Hospital, Florence, Italy
| | - Gordon Guyatt
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Canada
| | - Erin Hatcher
- Neuromuscular Clinic, McMaster University Medical Centre, Hamilton Health Sciences, Hamilton, Canada
| | - Steven W Ing
- Division of Endocrinology, Diabetes, & Metabolism, Ohio State University Wexner Medical Center, Columbus, USA
| | - Muhammad Kassim Javaid
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
| | - Sarah Khan
- Bone Research and Education Centre, Oakville, ON, Canada
| | - Roland Kocijan
- 1st Medical Department, Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA, Trauma Centre Meidling, Hanusch Hospital, 1140, Vienna, Austria
| | - E Michael Lewiecki
- New Mexico Clinical Research & Osteoporosis Center, Albuquerque, NM, USA
| | - Agnes Linglart
- APHP, Bicêtre Paris-Sud, University Paris Sud, Paris-Saclay, Le Kremlin Bicêtre, Paris, France
| | - Iman M'Hiri
- Bone Research and Education Centre, Oakville, ON, Canada
| | - Francesca Marini
- F.I.R.M.O. Italian Foundation for the Research on Bone Diseases, Florence, Italy
| | - Mark E Nunes
- Division of Medical Genetics and Metabolism, Valley Children's HealthCare, Madera, CA, USA
| | | | - Christian Roux
- Rheumatology Department, Hospital Pasteur 2 CHU, 06000, Nice, France
- Inserm, CNRS, iBV, Université Côte d'Azur, 06000, Nice, France
| | - Lothar Seefried
- Musculoskeletal Center Wuerzburg, University of Wuerzburg, Wuerzburg, Germany
| | - Susan R Starling
- Division of Clinical Genetics, Children's Mercy Kansas City, 2401 Gillham Road, Kansas City, MO, USA
| | - Leanne Ward
- Children's Hospital of Eastern Ontario, Department of Pediatrics, University of Ottawa, Ottawa, Ontario, Canada
| | - Liang Yao
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Canada
| | | | - Jill H Simmons
- Division of Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, USA
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Kim SM, Korkmaz F, Sims S, Ryu V, Yuen T, Zaidi M. Musculoskeletal and neurocognitive clinical significance of adult hypophosphatasia. Osteoporos Sarcopenia 2023; 9:115-120. [PMID: 38374822 PMCID: PMC10874721 DOI: 10.1016/j.afos.2023.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 12/03/2023] [Accepted: 12/12/2023] [Indexed: 02/21/2024] Open
Abstract
Hypophosphatasia (HPP), also called Rathbun disease, is a rare genetic disorder that is caused by the loss-of-function mutation in the ALPL gene encoding tissue non-specific alkaline phosphatase. Doctor Rathbun first described the case of a 3-week-old infant who presented with severe osteopenia, rickets, and multiple radiographic fractures, and died shortly after of epileptic seizure and respiratory distress. The term "hypophosphatasia" was coined as the patients' alkaline phosphatase levels were significantly low. Since then, our understanding of HPP has evolved, and now we appreciate causative genetic mutation and the broad spectrum of clinical presentation depending on the age of onset, severity, and skeletal involvement: perinatal, infantile, childhood, adult and odontohypophosphatasia. The new development of enzyme replacement with asfostase alfa has saved the lives of severe form of hypophosphatasia. However, it is still unclear and remains challenging how to manage adult HPP that often presents with mild and non-specific symptoms such as muscle pain, joint stiffness, fatigue, anxiety, or low bone mass, which are common in the general population and not necessarily attributed to HPP. In this review, we will present 3 unique cases of adult HPP and discuss the pathophysiology, clinical presentation particularly neuromuscular and neurocognitive symptoms and management of adult HPP.
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Affiliation(s)
- Se-Min Kim
- Center for Translational Medicine and Pharmacological Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Funda Korkmaz
- Center for Translational Medicine and Pharmacological Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Steve Sims
- Center for Translational Medicine and Pharmacological Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Vitaly Ryu
- Center for Translational Medicine and Pharmacological Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Tony Yuen
- Center for Translational Medicine and Pharmacological Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Mone Zaidi
- Center for Translational Medicine and Pharmacological Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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9
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Kuehn K, Hahn A, Seefried L. Impact of Restricted Phosphorus, Calcium-adjusted Diet on Musculoskeletal and Mental Health in Hypophosphatasia. J Endocr Soc 2023; 8:bvad150. [PMID: 38111621 PMCID: PMC10726311 DOI: 10.1210/jendso/bvad150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Indexed: 12/20/2023] Open
Abstract
Context Impairments in musculoskeletal and mental health are common in adults with Hypophosphatasia (HPP). Restricted phosphorus intake has been suggested to positively affect symptoms in HPP, but there is a lack of interventional evidence. Objective This work aimed to evaluate the effect of a phosphorus-restricted, calcium-adjusted diet on musculoskeletal and mental health in HPP. Methods A prospective, noncontrolled, single-center interventional study (NuSTEPS II) was conducted among outpatients at the Osteology Department, University of Wuerzburg, Germany. A total of 26 adults with an established HPP diagnosis received a standardized diet with a defined daily intake of phosphorus (1160-1240 mg/d) and calcium (870-930 mg/d) over 8 weeks. Main outcome measures were functional testing and patient-reported outcome measures. Results At 8 weeks, significant improvements were observed in usual gait speed (P = .028) and the chair-rise test (P = .019), while no significant changes were seen in the 6-minute walk test (P = .468) and the timed up-and-go test (P = .230). Pain was not significantly reduced according to the visual analog scale (VAS) (P = .061), pain subscale of the 36-Item Short-Form Health Survey (SF-36) (P = .346), and Pain Disability Index (P = .686). Further, there was a significant improvement in the SF-36 vitality subscale (P = .022) while all other subscales as well as the Lower Extremity Functional Scale (P = .670) and the Fatigue Assessment Scale (P = .392) did not change significantly. Adjustments of mineral intake were not associated with relevant alterations regarding the intake of energy and energy-supplying nutrients or body composition. Conclusion Adjusting phosphorus and calcium intake may positively affect individual symptoms in adults with HPP, but overall clinical effectiveness regarding major issues like pain and endurance appears limited.
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Affiliation(s)
- Katinka Kuehn
- Faculty of Natural Science, Institute of Food Science and Human Nutrition, Leibniz University Hannover, 30167 Hanover, Germany
| | - Andreas Hahn
- Faculty of Natural Science, Institute of Food Science and Human Nutrition, Leibniz University Hannover, 30167 Hanover, Germany
| | - Lothar Seefried
- Clinical Trial Unit, Orthopedic Institute, Koenig-Ludwig-Haus, University of Wuerzburg, 97074 Wuerzburg, Germany
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10
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Hepp N, Frederiksen AL, Duno M, Jørgensen NR, Jensen JEB. Biochemical and clinical manifestations in adults with hypophosphatasia: a national cross-sectional study. Osteoporos Int 2022; 33:2595-2605. [PMID: 35986118 DOI: 10.1007/s00198-022-06536-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 08/15/2022] [Indexed: 11/24/2022]
Abstract
UNLABELLED Hypophosphatasia (HPP) is a rare disease affecting bone mineralization. Adults with HPP have an increased occurrence of low-energy fractures, which cannot be explained by reduced bone mass assessed by dual energy X-ray absorptiometry. The bone phenotype in adults with HPP requires further studies investigating bone strength and bone structural parameters. INTRODUCTION Hypophosphatasia (HPP) is a rare inherited disorder of bone and mineral metabolism, characterized by broad-ranging clinical manifestations and severity. However, studies investigating the clinical spectrum in adults with HPP compared to a control group are scarce. The aim of this study was to evaluate biochemical and clinical characteristics as well as bone health in a Danish cohort of adults with HPP. METHODS We conducted a cross-sectional study assessing biochemical parameters, fracture prevalence, bone mineral density (BMD), bone turnover markers, physical performance and pain characteristics in 40 adults with HPP and 40 sex-, age-, BMI- and menopausal status-matched healthy controls. RESULTS Patients with HPP had a significantly higher prevalence of non-vertebral, low-energy fractures (p = < 0.001). BMD at the lumbar spine, total hip, femoral neck, forearm and whole body did not differ between the groups. Low levels of the bone-specific alkaline phosphatase correlated significantly with higher BMD at the lumbar spine and femoral neck in both groups. The bone formation marker N-terminal propeptide of type 1 procollagen was significantly lower in patients with HPP than healthy controls (p = 0.006). Adults with HPP had significantly reduced walking capability (p = < 0.001) and lower body strength (p = < 0.001). Chronic pain was significantly more prevalent in adults with HPP than the control group (p = 0.029). CONCLUSIONS The increased occurrence of low-energy fractures in adults with HPP is not explained by low BMD. Adults with HPP have reduced physical performance when compared with healthy controls.
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Affiliation(s)
- Nicola Hepp
- Department of Endocrinology, Copenhagen University Hospital Hvidovre, Kettegaard Alle 30, 2650, Hvidovre, Denmark.
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3 B, 2200, Copenhagen, Denmark.
| | - Anja Lisbeth Frederiksen
- Department of Clinical Genetics, Aalborg University Hospital, Ladegaardsgade 5, 9000, Aalborg C, Denmark
- Department of Clinical Research, Aalborg University, Fredrik Bajers Vej 7K, 9220, Aalborg Ø, Denmark
| | - Morten Duno
- Department of Clinical Genetics, University Hospital Copenhagen Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark
| | - Niklas Rye Jørgensen
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3 B, 2200, Copenhagen, Denmark
- Department of Clinical Biochemistry, Rigshospitalet, Valdemar Hansens Vej 13, 2600, Glostrup, Denmark
| | - Jens-Erik Beck Jensen
- Department of Endocrinology, Copenhagen University Hospital Hvidovre, Kettegaard Alle 30, 2650, Hvidovre, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3 B, 2200, Copenhagen, Denmark
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11
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Whyte MP, Zhang F, Wenkert D, Mack KE, Bijanki VN, Ericson KL, Coburn SP. Hypophosphatasia: Vitamin B 6 status of affected children and adults. Bone 2022; 154:116204. [PMID: 34547524 DOI: 10.1016/j.bone.2021.116204] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 12/20/2022]
Abstract
Hypophosphatasia (HPP) is the heritable dento-osseous disease caused by loss-of-function mutation(s) of the gene ALPL that encodes the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP). TNSALP is a cell-surface homodimeric phosphomonoester phosphohydrolase expressed in healthy people especially in the skeleton, liver, kidneys, and developing teeth. In HPP, diminished TNSALP activity leads to extracellular accumulation of its natural substrates including inorganic pyrophosphate (PPi), an inhibitor of mineralization, and pyridoxal 5'-phosphate (PLP), the principal circulating form of vitamin B6 (B6). Autosomal dominant and autosomal recessive inheritance involving >450 usually missense defects scattered throughout ALPL largely explains the remarkably broad-ranging severity of this inborn-error-of-metabolism. In 1985 when we identified elevated plasma PLP as a biochemical hallmark of HPP, all 14 investigated affected children and adults had markedly increased PLP levels. However, pyridoxal (PL), the dephosphorylated form of PLP that enters cells to cofactor many enzymatic reactions, was not low but often inexplicably elevated. Levels of pyridoxic acid (PA), the B6 degradation product quantified to assess B6 sufficiency, were unremarkable. Canonical signs or symptoms of B6 deficiency or toxicity were absent. B6-dependent seizures in infants with life-threatening HPP were later explained by their profound deficiency of TNSALP activity blocking PLP dephosphorylation to PL and diminishing gamma-aminobutyric acid synthesis in the brain. Now, there is speculation that altered B6 metabolism causes further clinical complications in HPP. Herein, we assessed the plasma PL and PA levels accompanying previously reported elevated plasma PLP concentrations in 150 children and adolescents with HPP. Their mean (SD) plasma PL level was nearly double the mean for our healthy pediatric controls: 66.7 (59.0) nM versus 37.1 (22.2) nM (P < 0.0001), respectively. Their PA levels were broader than our pediatric control range, but their mean value was normal; 40.2 (25.1) nM versus 39.3 (9.9) nM (P = 0.7793), respectively. In contrast, adults with HPP often had plasma PL and PA levels suggestive of dietary B6 insufficiency. We discuss why the B6 levels of our pediatric patients with HPP would not cause B6 toxicity or deficiency, whereas in affected adults dietary B6 insufficiency can develop.
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Affiliation(s)
- Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO 63110, USA.
| | - Fan Zhang
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA.
| | - Deborah Wenkert
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA.
| | - Karen E Mack
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA.
| | - Vinieth N Bijanki
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA.
| | - Karen L Ericson
- Department of Chemistry, Purdue University Fort Wayne, Fort Wayne, IN 46805, USA.
| | - Stephen P Coburn
- Department of Chemistry, Purdue University Fort Wayne, Fort Wayne, IN 46805, USA.
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12
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Sanabria-de la Torre R, Martínez-Heredia L, González-Salvatierra S, Andújar-Vera F, Iglesias-Baena I, Villa-Suárez JM, Contreras-Bolívar V, Corbacho-Soto M, Martínez-Navajas G, Real PJ, García-Fontana C, Muñoz-Torres M, García-Fontana B. Characterization of Genetic Variants of Uncertain Significance for the ALPL Gene in Patients With Adult Hypophosphatasia. Front Endocrinol (Lausanne) 2022; 13:863940. [PMID: 35498405 PMCID: PMC9047899 DOI: 10.3389/fendo.2022.863940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/14/2022] [Indexed: 11/29/2022] Open
Abstract
Hypophosphatasia (HPP) a rare disease caused by mutations in the ALPL gene encoding for the tissue-nonspecific alkaline phosphatase protein (TNSALP), has been identified as a potentially under-diagnosed condition worldwide which may have higher prevalence than currently established. This is largely due to the overlapping of its symptomatology with that of other more frequent pathologies. Although HPP is usually associated with deficient bone mineralization, the high genetic variability of ALPL results in high clinical heterogeneity, which makes it difficult to establish a specific HPP symptomatology. In the present study, three variants of ALPL gene with uncertain significance and no previously described (p.Del Glu23_Lys24, p.Pro292Leu and p.His379Asn) were identified in heterozygosis in patients diagnosed with HPP. These variants were characterized at phenotypic, functional and structural levels. All genetic variants showed significantly lower in vitro ALP activity than the wild-type (WT) genotype (p-value <0.001). Structurally, p.His379Asn variant resulted in the loss of two Zn2+ binding sites in the protein dimer which may greatly affect ALP activity. In summary, we identified three novel ALPL gene mutations associated with adult HPP. The correct identification and characterization of new variants and the subsequent study of their phenotype will allow the establishment of genotype-phenotype relationships that facilitate the management of the disease as well as making it possible to individualize treatment for each specific patient. This would allow the therapeutic approach to HPP to be personalized according to the unique genetic characteristics and clinical manifestations of each patient.
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Affiliation(s)
- Raquel Sanabria-de la Torre
- Department of Medicine, University of Granada, Granada, Spain
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
| | - Luis Martínez-Heredia
- Department of Medicine, University of Granada, Granada, Spain
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
| | - Sheila González-Salvatierra
- Department of Medicine, University of Granada, Granada, Spain
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
| | - Francisco Andújar-Vera
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Department of Computer Science and Artificial Intelligence, University of Granada, Granada, Spain
- Andalusian Research Institute in Data Science and Computational Intelligence (DaSCI Institute), Granada, Spain
| | | | - Juan Miguel Villa-Suárez
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Clinical Analysis Unit, University Hospital Clínico San Cecilio, Granada, Spain
| | - Victoria Contreras-Bolívar
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, Granada, Spain
| | | | - Gonzalo Martínez-Navajas
- Gene Regulation, Stem Cells and Development Lab, Pfizer-University of Granada-Junta de Andalucía Centre for Genomics and Oncological Research (GENYO), Granada, Spain
- Department of Biochemistry and Molecular Biology I, Faculty of Science, University of Granada, Granada, Spain
| | - Pedro J. Real
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Gene Regulation, Stem Cells and Development Lab, Pfizer-University of Granada-Junta de Andalucía Centre for Genomics and Oncological Research (GENYO), Granada, Spain
- Department of Biochemistry and Molecular Biology I, Faculty of Science, University of Granada, Granada, Spain
| | - Cristina García-Fontana
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, Granada, Spain
- Biomedical Research Network in Fragility and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- *Correspondence: Cristina García-Fontana, ; Manuel Muñoz-Torres,
| | - Manuel Muñoz-Torres
- Department of Medicine, University of Granada, Granada, Spain
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, Granada, Spain
- Biomedical Research Network in Fragility and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- *Correspondence: Cristina García-Fontana, ; Manuel Muñoz-Torres,
| | - Beatriz García-Fontana
- Instituto de Investigación Biosanitaria de Granada, Granada, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, Granada, Spain
- Biomedical Research Network in Fragility and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
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13
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Abstract
Hypophosphatasia (HPP) is an inherited metabolic disease caused by loss-of-function mutations in the tissue non-specific alkaline phosphatase (TNAP) gene. Reduced activity of TNAP leads to the accumulation of its substrates, mainly inorganic pyrophosphate and pyridoxal-5′-phosphate, metabolic aberrations that largely explain the musculoskeletal and systemic features of the disease. More than 400 ALPL mutations, mostly missense, are reported to date, transmitted by either autosomal dominant or recessive mode. Severe disease is rare, with incidence ranging from 1:100,000 to 1:300,000 live births, while the estimated prevalence of the less severe adult form is estimated to be between 1:3100 to 1:508, in different countries in Europe. Presentation largely varies, ranging from death in utero to asymptomatic adults. In infants and children, clinical features include skeletal, respiratory and neurologic complications, while recurrent, poorly healing fractures, muscle weakness and arthropathy are common in adults. Persistently low serum alkaline phosphatase is the cardinal biochemical feature of the disease. Management requires a dedicated multidisciplinary team. In mild cases, treatment is usually symptomatic. Severe cases, with life-threating or debilitating complications, can be successfully treated with enzyme replacement therapy with asfotase alfa.
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14
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Trinh TT, Blasco H, Maillot F, Bakhos D. Hearing loss in inherited metabolic disorders: A systematic review. Metabolism 2021; 122:154841. [PMID: 34333001 DOI: 10.1016/j.metabol.2021.154841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 07/14/2021] [Accepted: 07/15/2021] [Indexed: 10/20/2022]
Abstract
Inherited metabolic disorders (IMDs) have been observed in individuals with hearing loss (HL), but IMDs are rarely the cause of syndromic HL. With early diagnosis, management of HL is more effective and cortical reorganization is possible with hearing aids or cochlear implants. This review describes relationships between IMDs and HL in terms of incidence, etiology of HL, pathophysiology, and treatment. Forty types of IMDs are described in the literature, mainly in case reports. Management and prognosis are noted where existing. We also describe IMDs with HL given age of occurrence of HL. Reviewing the main IMDs that are associated with HL may provide an additional clinical tool with which to better diagnose syndromic HL.
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Affiliation(s)
- T-T Trinh
- CHRU de Tours, service ORL et Chirurgie Cervico-Faciale, Tours, France.
| | - H Blasco
- Laboratoire de Biochimie et Biologie Moléculaire, Tours, France; Université François Rabelais, Tours, France; INSERM U1253, Tours, France
| | - F Maillot
- Université François Rabelais, Tours, France; INSERM U1253, Tours, France; CHU de Tours, service de Médecine Interne, Tours, France
| | - D Bakhos
- CHRU de Tours, service ORL et Chirurgie Cervico-Faciale, Tours, France; Université François Rabelais, Tours, France; INSERM U1253, Tours, France
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15
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Pan WJ, Pradhan R, Pelto R, Seefried L. Pharmacokinetics of Asfotase Alfa in Adult Patients With Pediatric-Onset Hypophosphatasia. J Clin Pharmacol 2021; 61:1334-1343. [PMID: 33822385 PMCID: PMC8518624 DOI: 10.1002/jcph.1870] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 04/01/2021] [Indexed: 11/24/2022]
Abstract
Hypophosphatasia is a rare metabolic disease resulting from variant(s) in the gene‐encoding tissue‐nonspecific isozyme of alkaline phosphatase. In this 13‐week, phase 2a, multicenter, randomized, open‐label, dose‐response study (ClinicalTrials.gov: NCT02797821), the pharmacokinetics of asfotase alfa, an enzyme replacement therapy approved for the treatment of hypophosphatasia, was assessed in adult patients with pediatric‐onset hypophosphatasia. In total, 27 adults were randomly assigned 1:1:1 to a single subcutaneous dose of asfotase alfa (0.5, 2.0, or 3.0 mg/kg) during week 1. From week 3 to week 9, patients received 0.5, 2.0, or 3.0 mg/kg subcutaneously 3 times per week (equivalent to 1.5, 6.0, or 9.0 mg/kg/wk, respectively). Noncompartmental analysis revealed exposure (maximum concentration in the dosing interval and area under the concentration‐time curve from time 0 to infinity) to asfotase alfa increased between single‐ and multiple‐dose administration and with increasing doses; however, extensive interindividual variability was observed in the concentration‐time profiles within each dose cohort. Median terminal elimination half‐life was ≈5 days following multiple‐dose administration, with steady state achieved by approximately day 29. Dose‐normalized exposure data indicated that asfotase alfa activity was approximately dose‐proportional within the studied dose range. Additionally, dose‐normalized exposure was comparable across body mass index categories of <25, ≥25 to <30, and ≥30 kg/m2, indicating that asfotase alfa dosing bioavailability was consistent in these patients, including those who were obese. These data, together with previously published pharmacodynamic results in this study population, support the use of asfotase alfa at the recommended dose of 6 mg/kg/wk in adults with pediatric‐onset hypophosphatasia.
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Affiliation(s)
- Wei-Jian Pan
- Alexion Pharmaceuticals, Inc., Boston, Massachusetts, USA
| | | | - Ryan Pelto
- Alexion Pharmaceuticals, Inc., Boston, Massachusetts, USA
| | - Lothar Seefried
- Orthopedic Department, University of Würzburg, Würzburg, Bavaria, Germany
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16
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Kishnani PS, Del Angel G, Zhou S, Rush ET. Investigation of ALPL variant states and clinical outcomes: An analysis of adults and adolescents with hypophosphatasia treated with asfotase alfa. Mol Genet Metab 2021; 133:113-121. [PMID: 33814268 DOI: 10.1016/j.ymgme.2021.03.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 02/03/2021] [Accepted: 03/14/2021] [Indexed: 12/22/2022]
Abstract
BACKGROUND Hypophosphatasia (HPP), a rare metabolic disease, can be inherited in an autosomal recessive (biallelic) or an autosomal dominant (monoallelic) manner. Most of the severe, early-onset, frequently lethal HPP in infants is acquired through recessive inheritance; less severe, later-onset, typically nonlethal HPP phenotypes are acquired through either dominant or recessive inheritance. HPP's variable clinical presentation arises from >400 identified ALPL pathogenic variants with likely variable penetrance, especially with autosomal dominant inheritance. This post hoc analysis investigated the relationship between ALPL variant state (biallelic and monoallelic) and clinical outcomes with asfotase alfa in HPP. METHODS Data were pooled from two phase 2, randomized, open-label studies in adolescents and adults with HPP; one study evaluated the efficacy and safety of different doses of asfotase alfa (n = 25), and the other assessed the pharmacodynamics and safety of asfotase alfa (n = 19). Patients were grouped by ALPL variant state (biallelic or monoallelic). Available data from both studies included ALPL pathogenic variant state, Baseline characteristics, HPP-specific medical history, and Baseline TNSALP substrate levels (inorganic pyrophosphate [PPi] and pyridoxal 5'-phosphate [PLP]) concentrations). Clinical outcomes over 5 years of treatment were available from only the efficacy and safety study. RESULTS In total, 44 patients with known variant status were included in the pooled analysis (biallelic, n = 30; monoallelic, n = 14). The most common pathogenic variant was c.571G > A (p.Glu191Lys) in biallelic patients (allele frequency: 19/60) and c.1133A > T (p.Asp378Val) in monoallelic patients (allele frequency: 7/28). Median (min, max) Baseline PPi concentrations were significantly higher in patients with a biallelic vs monoallelic variant state (5.3 [2.2, 12.1] vs 4.3 [3.5, 7.4] μM; P = 0.0113), as were Baseline PLP concentrations (221.4 [62.4, 1590.0] vs 75.1 [28.8, 577.0] ng/mL; P= 0.0022). HPP-specific medical history was generally similar between biallelic and monoallelic patients in terms of incidence and type of manifestations; notable exceptions included fractures, which were more common among monoallelic patients, and delayed walking and bone deformities such as abnormally shaped chest and head and bowing of arms or legs, which were more common among biallelic patients. Data from the efficacy and safety study (n = 19) showed that median PPi and PLP concentrations were normalized over 5 years of treatment in patients with both variant states. Median % predicted distance walked on the 6-Minute Walk Test remained within the normal range for monoallelic patients over 4 years of treatment, and improved from below normal (<84%) to normal in biallelic patients. CONCLUSIONS Although patients with biallelic variants had significantly higher Baseline PPi and PLP levels than monoallelic variants, both groups generally showed similar pretreatment Baseline clinical characteristics. Treatment with asfotase alfa for up to 5 years normalized TNSALP substrate concentrations and improved functional outcomes, with no clear differences between biallelic and monoallelic variant states. This study suggests that patients with HPP have significant disease burden, regardless of ALPL variant state.
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Affiliation(s)
- Priya S Kishnani
- Department of Pediatrics, Duke University Medical Center, 2351 Erwin Road, Durham, NC, USA.
| | | | - Shanggen Zhou
- Covance, Inc., 206 Carnegie Center Dr, Princeton, NJ, USA.
| | - Eric T Rush
- Children's Mercy Hospital Kansas City, 2401 Gillham Rd, Kansas City, MO, USA; University of Missouri-Kansas City School of Medicine, Kansas City, MO, USA; University of Kansas School of Medicine, Kansas City, KS, USA.
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17
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Fenn JS, Lorde N, Ward JM, Borovickova I. Hypophosphatasia. J Clin Pathol 2021; 74:635-640. [PMID: 33931563 DOI: 10.1136/jclinpath-2021-207426] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 11/04/2022]
Abstract
Hypophosphatasia (HPP) is a group of inherited disorders characterised by the impaired mineralisation of bones and/or teeth and low serum alkaline phosphatase (ALP) activity. It is caused by a mutation in the ALPL gene encoding the tissue-non-specific isoenzyme of ALP (TNSALP) resulting in a loss of function. The disease is highly heterogenous in its clinical expression ranging from stillbirth without mineralised bone to the mild form of late adult onset with symptoms and signs such as musculoskeletal pain, arthropathy, lower-extremity fractures, premature loss of teeth or an incidental finding of reduced serum ALP activity. A classification based on the age at diagnosis and the presence or absence of bone symptoms was historically used: perinatal, prenatal benign, infantile, childhood, adult and odontohypophosphatasia. These subtypes are known to have overlapping signs and complications. Three forms of HPP distinguishable by their genetic characteristics have been described: severe, moderate and mild. Severe forms of HPP (perinatal and infantile severe) are recessively inherited, whereas moderate HPP may be dominantly or recessively inherited. The biochemical hallmark of HPP is persistently low serum ALP for age and increase in natural substrates of TNSALP, pyridoxal 5'-phosphate and phosphoethanolamine supported by radiological findings. The diagnosis is confirmed by ALPL sequencing. A multidisciplinary team of experts is essential for the effective management. Calcium restriction is recommended in infants/children to manage hypercalcaemia. A targeted enzyme replacement therapy for HPP has become available and correct diagnosis is crucial to allow early treatment.
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Affiliation(s)
- Jonathan Samuel Fenn
- Black Country Pathology Services, The Royal Wolverhampton NHS Trust, Wolverhampton, UK
| | - Nathan Lorde
- Department of Clinical Chemistry, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - John Martin Ward
- Department of Radiology, McGill University Health Center, Montreal, Québec, Canada
| | - Ingrid Borovickova
- Department of Biochemical Genetics, Children's Health Ireland at Temple Street, Dublin, Ireland
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18
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Hypophosphatasia: A Unique Disorder of Bone Mineralization. Int J Mol Sci 2021; 22:ijms22094303. [PMID: 33919113 PMCID: PMC8122659 DOI: 10.3390/ijms22094303] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/18/2021] [Accepted: 04/19/2021] [Indexed: 12/25/2022] Open
Abstract
Hypophosphatasia (HPP) is a rare genetic disease characterized by a decrease in the activity of tissue non-specific alkaline phosphatase (TNSALP). TNSALP is encoded by the ALPL gene, which is abundantly expressed in the skeleton, liver, kidney, and developing teeth. HPP exhibits high clinical variability largely due to the high allelic heterogeneity of the ALPL gene. HPP is characterized by multisystemic complications, although the most common clinical manifestations are those that occur in the skeleton, muscles, and teeth. These complications are mainly due to the accumulation of inorganic pyrophosphate (PPi) and pyridoxal-5′-phosphate (PLP). It has been observed that the prevalence of mild forms of the disease is more than 40 times the prevalence of severe forms. Patients with HPP present at least one mutation in the ALPL gene. However, it is known that there are other causes that lead to decreased alkaline phosphatase (ALP) levels without mutations in the ALPL gene. Although the phenotype can be correlated with the genotype in HPP, the prediction of the phenotype from the genotype cannot be made with complete certainty. The availability of a specific enzyme replacement therapy for HPP undoubtedly represents an advance in therapeutic strategy, especially in severe forms of the disease in pediatric patients.
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19
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Vieira LHR, Peixoto KC, Flósi CL, de Farias MLF, Madeira M. Active search of adult patients with persistently low serum alkaline phosphatase levels for the diagnosis of hypophosphatasia. ARCHIVES OF ENDOCRINOLOGY AND METABOLISM 2021; 65:289-294. [PMID: 33844893 PMCID: PMC10065342 DOI: 10.20945/2359-3997000000347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Objective Alkaline phosphatase (ALP) is the main laboratory marker of hypophosphatasia (HPP), a rare disease unknown to most physicians. The prevalence of HPP has been widely discussed in the literature due to the diverse phenotypes of HPP. The purpose of this study was to search for patients with hypophosphatasemia based on previous biochemistry tests and reevaluate them to confirm the diagnosis of HPP. Methods A total of 289,247 biochemical tests for ALP in adults were performed from 2015 to 2019 in two tertiary hospitals in Rio de Janeiro were reviewed (Clementino Fraga Filho University Hospital - HUCFF - and Bonsucesso Federal Hospital - BFH). Results A total of 1,049 patients were identified with ALP levels below 40 U/L, and 410 patients had hypophosphatasemia confirmed by at least two exams. After the active search of medical reports and/or interviews based on structured questionnaires, 398 subjects were excluded due to secondary causes of reduced ALP. The remaining 12 patients were invited to attend the medical consultation at HUCFF, accompanied by at least one first-degree relative. None of the patients or their relatives had a history or clinical manifestations consistent with HPP. Serum ALP was within reference values in all relatives, but persistently low in further laboratory evaluation in all the 12 patients, in whom secondary causes were ruled out. Thus, we cannot exclude the possibility that they might carry the mutations associated with HPP. Conclusion Further image evaluations and genetic testing would be appropriate to confirm this asymptomatic adult form of HPP.
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Affiliation(s)
- Lucio Henrique Rocha Vieira
- Divisão de Endocrinologia, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil,
| | - Kleison Cordeiro Peixoto
- Laboratório de Bioquímica, Hospital Universitário Clementino Fraga Filho, Rio de Janeiro, RJ, Brasil
| | - Caroline Leal Flósi
- Divisão de Endocrinologia, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - Maria Lucia Fleiuss de Farias
- Divisão de Endocrinologia, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - Miguel Madeira
- Divisão de Endocrinologia, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
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20
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Abstract
Delineating the genetic background and the underlying pathophysiology of rare skeletal dysplasias enables a broader understanding of these disorders as well as novel perspectives regarding differential diagnosis and targeted development of therapeutic approaches. Hypophosphatasia (HPP) due to genetically determined Alkaline Phosphatase deficiency exemplifies this development. While an enzyme replacement therapy could be established for severe HPP with the prevailing bone manifestation, the clinical impact of not immediately bone-related manifestations just being successively understood. Correspondingly, the elucidation of the pathophysiology underlying renal phosphate wasting expanded our knowledge regarding phosphate metabolism and bone health and facilitated the development of an anti-FGF-23 Antibody for targeted treatment of X‑linked Hypophosphatemia (XLH). Evolutions regarding the nosology of osteogenesis imperfecta (OI) along with the identification of further causative genes also detected in the context of genetically determined osteoporosis illustrate the pathophysiologic interrelation between monogenetic bone dysplasias and multifactorial osteoporosis. While current therapeutic strategies for OI follow osteoporosis treatment, the expanding knowledge about OI forms the fundament for establishing improved treatment strategies-for both OI and osteoporosis. Similar developments are emerging regarding rare skeletal disorders like Achondroplasia, Fibrodysplasia ossificans progressive and Morbus Morquio (Mukopolysaccharidosis Type IV).
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Affiliation(s)
- Lothar Seefried
- Orthopädisches Zentrum für Muskuloskeletale Forschung, Universität Würzburg, Brettreichstr. 11, 97074, Würzburg, Deutschland.
| | - Franz Jakob
- Orthopädisches Zentrum für Muskuloskeletale Forschung, Universität Würzburg, Brettreichstr. 11, 97074, Würzburg, Deutschland
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21
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Jandl NM, Schmidt T, Rolvien T, Stürznickel J, Chrysostomou K, von Vopelius E, Volk AE, Schinke T, Kubisch C, Amling M, Barvencik F. Genotype-Phenotype Associations in 72 Adults with Suspected ALPL-Associated Hypophosphatasia. Calcif Tissue Int 2021; 108:288-301. [PMID: 33191482 PMCID: PMC7881968 DOI: 10.1007/s00223-020-00771-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 10/12/2020] [Indexed: 12/11/2022]
Abstract
Hypophosphatasia (HPP) is a rare inborn error of metabolism due to a decreased activity of tissue nonspecific alkaline phosphatase (TNSALP). As the onset and severity of HPP are heterogenous, it can be challenging to determine the pathogenicity of detected rare ALPL variants in symptomatic patients. We aimed to characterize patients with rare ALPL variants to propose which patients can be diagnosed with adult HPP. We included 72 patients with (1) clinical symptoms of adult HPP or positive family history and (2) low TNSALP activity and/or high pyridoxal 5'-phosphate (PLP) levels, who underwent ALPL gene sequencing. The patients were analyzed and divided into three groups depending on ALPL variant pathogenicity according to the classification of the American College of Medical Genetics and Genomics (ACMG). Reported pathogenic (n = 34 patients), rare (n = 17) and common (n = 21) ALPL variants only were found. Muscular complaints were the most frequent symptoms (> 80%), followed by bone affection (> 50%). Tooth involvement was significantly more common in patients with pathogenic or rare ALPL variants. Seven rare variants could be classified as likely pathogenic (ACMG class 4) of which five have not yet been described. Inconclusive genetic findings and less specific symptoms make diagnosis difficult in cases where adult HPP is not obvious. As not every pathogenic or rare ALPL variant leads to a manifestation of HPP, only patients with bone complications and at least one additional complication concerning teeth, muscle, central nervous and mental system, repeated low TNSALP activity and high PLP levels should be diagnosed as adult HPP if rare ALPL gene variants of ACMG class 4 or higher support the diagnosis.
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Affiliation(s)
- Nico Maximilian Jandl
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529, Hamburg, Germany
- Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany
| | - Tobias Schmidt
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529, Hamburg, Germany
| | - Tim Rolvien
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529, Hamburg, Germany
- Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany
| | - Julian Stürznickel
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529, Hamburg, Germany
| | - Konstantin Chrysostomou
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529, Hamburg, Germany
| | - Emil von Vopelius
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529, Hamburg, Germany
- Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany
| | - Alexander E Volk
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529, Hamburg, Germany
| | - Christian Kubisch
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany
| | - Michael Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529, Hamburg, Germany
| | - Florian Barvencik
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529, Hamburg, Germany.
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22
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Pierpont EI, Simmons JH, Spurlock KJ, Shanley R, Sarafoglou KM. Impact of pediatric hypophosphatasia on behavioral health and quality of life. Orphanet J Rare Dis 2021; 16:80. [PMID: 33579333 PMCID: PMC7881480 DOI: 10.1186/s13023-021-01722-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 02/02/2021] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Hypophosphatasia (HPP) is a rare genetic disorder caused by loss-of-function mutations in the ALPL gene encoding tissue nonspecific alkaline phosphatase. It is characterized by defective bone mineralization associated with low alkaline phosphatase activity. Clinical features of pediatric HPP are highly variable, and can include premature loss of teeth, musculoskeletal problems, and impaired mobility. The effects of pediatric HPP on sleep, mood, regulation of attention and behavior, and other aspects of behavioral health have not been comprehensively studied. METHODS Parents of 30 children with HPP (14 females, 16 males) between the ages of 3 and 16 years (mean age = 8.0 years) enrolled in this cross-sectional survey-based study. Molecular genetic and biochemical testing as well as clinical records were reviewed to verify diagnosis of HPP. The cohort included 15 patients with a more clinically severe presentation of HPP who had received treatment with enzyme replacement therapy (asfotase alfa) and 15 children with less severe HPP who were treatment-naïve. Parents provided information regarding psychopathological comorbidity, emotional and behavioral well-being, and quality of life. RESULTS Clinically significant behavioral health challenges were evident in 67% of children with HPP. The most common behavioral findings included sleep disturbance and symptoms of attention deficit hyperactivity disorder (ADHD), each of which were observed ≥ 50% of individuals. Sleep disturbance, pain interference, poor behavioral regulation, and mood/anxiety symptoms were associated with reduced physical and psychosocial quality of life. Behavioral concerns were evident among children with HPP receiving asfotase alfa treatment as well as among children with clinically less severe disease who had not initiated therapy. Although most children in the cohort (77%) had age-typical development of adaptive skills, emotional and behavioral challenges were associated with weaker adaptive function. CONCLUSIONS Children with HPP are at increased risk for ADHD symptoms and other behavioral health challenges. There is likely an under-recognition of these findings in clinical practice.
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Affiliation(s)
- Elizabeth I Pierpont
- Department of Pediatrics, University of Minnesota Medical School, 2450 Riverside Avenue South, RPB 550, Minneapolis, MN, 55454, USA.
| | - Jill H Simmons
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Katherine J Spurlock
- Department of Pediatrics, University of Minnesota Medical School, 2450 Riverside Avenue South, RPB 550, Minneapolis, MN, 55454, USA
| | - Ryan Shanley
- Biostatistics Core, Masonic Cancer Center, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Kyriakie M Sarafoglou
- Department of Pediatrics, University of Minnesota Medical School, 2450 Riverside Avenue South, RPB 550, Minneapolis, MN, 55454, USA.,Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy, Minneapolis, MN, 55455, USA
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23
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Stürznickel J, Schmidt FN, von Vopelius E, Delsmann MM, Schmidt C, Jandl NM, Oheim R, Barvencik F. Bone healing and reactivation of remodeling under asfotase alfa therapy in adult patients with pediatric-onset hypophosphatasia. Bone 2021; 143:115794. [PMID: 33301963 DOI: 10.1016/j.bone.2020.115794] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 10/16/2020] [Accepted: 12/03/2020] [Indexed: 01/13/2023]
Abstract
Hypophosphatasia (HPP) is a hereditary musculoskeletal disorder caused by inactivating variants in the ALPL gene and subsequently reduced serum tissue-nonspecific alkaline phosphatase (TNSALP) activity. This inborn error of metabolism results in decreased bone quality, accumulations of osteoid, and reduced bone mineralization. Increased incidence of fractures and prolonged bone healing are characteristic features for HPP. Available enzyme replacement therapy (asfotase alfa), was reported to recover bone mineralization and bone quality in adult HPP patients. Moreover, it was shown that asfotase alfa improved fracture healing of former nonunions in two adult HPP patients. We hypothesized that the nonunions are filled partially with osteoid, offering great potential to benefit from the treatment with asfotase alfa to promote bone healing. In the present study, we report three adult patients with pediatric-onset HPP and detected ALPL-mutations with prolonged bone healing after arthrodesis, tibial stress fracture, and osteotomy. After the initiation of asfotase alfa, immediately increased levels of alkaline phosphatase (ALP) and bone-specific ALP, as well as decreased levels of pyridoxal-5-phosphate (PLP), were detected in biochemical analysis. Importantly, even after up to 5 years of non-healing, a progredient consolidation was shown, assessed by a custom three-dimensional evaluation of repeated cone-beam computed tomography (CBCT) images, characterized by rapidly increasing levels of bone volume per tissue volume (BV/TV) within the volume of interest (i.e., the region of the non-healing bone). These radiographical findings were in line with the reported restoration of functional ability and pain-free full weight-bearing, as well as increased neuromuscular parameters (e.g., improved muscle strength). Taken together, our findings indicate that asfotase alfa improves the osseous consolidation of nonunions likely due to re-mineralization of osteoid tissue filling the former gap and improving the functional ability in adult HPP patients, characterized by increasing levels of BV/TV assessed via an innovative three-dimensional evaluation of CBCT images.
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Affiliation(s)
- Julian Stürznickel
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Felix N Schmidt
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Emil von Vopelius
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Maximilian M Delsmann
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Constantin Schmidt
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Nico Maximilian Jandl
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ralf Oheim
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Martin Zeitz Center for Rare Diseases, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Florian Barvencik
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Martin Zeitz Center for Rare Diseases, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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24
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TNAP as a New Player in Chronic Inflammatory Conditions and Metabolism. Int J Mol Sci 2021; 22:ijms22020919. [PMID: 33477631 PMCID: PMC7831495 DOI: 10.3390/ijms22020919] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/14/2021] [Accepted: 01/14/2021] [Indexed: 12/19/2022] Open
Abstract
This review summarizes important information on the ectoenzyme tissue-nonspecific alkaline phosphatase (TNAP) and gives a brief insight into the symptoms, diagnostics, and treatment of the rare disease Hypophosphatasia (HPP), which is resulting from mutations in the TNAP encoding ALPL gene. We emphasize the role of TNAP beyond its well-known contribution to mineralization processes. Therefore, above all, the impact of the enzyme on central molecular processes in the nervous system and on inflammation is presented here.
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25
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Ghatge MS, Al Mughram M, Omar AM, Safo MK. Inborn errors in the vitamin B6 salvage enzymes associated with neonatal epileptic encephalopathy and other pathologies. Biochimie 2021; 183:18-29. [PMID: 33421502 DOI: 10.1016/j.biochi.2020.12.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 12/28/2020] [Accepted: 12/30/2020] [Indexed: 12/28/2022]
Abstract
Pyridoxal 5'-phosphate (PLP), the active cofactor form of vitamin B6 is required by over 160 PLP-dependent (vitamin B6) enzymes serving diverse biological roles, such as carbohydrates, amino acids, hemes, and neurotransmitters metabolism. Three key enzymes, pyridoxal kinase (PL kinase), pyridoxine 5'-phosphate oxidase (PNPO), and phosphatases metabolize and supply PLP to PLP-dependent enzymes through the salvage pathway. In born errors in the salvage enzymes are known to cause inadequate levels of PLP in the cell, particularly in neuronal cells. The resulting PLP deficiency is known to cause or implicated in several pathologies, most notably seizures. One such disorder, PNPO-dependent neonatal epileptic encephalopathy (NEE) results from natural mutations in PNPO and leads to null or reduced enzymatic activity. NEE does not respond to conventional antiepileptic drugs but may respond to treatment with the B6 vitamers PLP and/or pyridoxine (PN). In born errors that lead to PLP deficiency in cells have also been reported in PL kinase, however, to date none has been associated with epilepsy or seizure. One such pathology is polyneuropathy that responds to PLP therapy. Phosphatase deficiency or hypophosphatasia disorder due to pathogenic mutations in alkaline phosphatase is known to cause seizures that respond to PN therapy. In this article, we review the biochemical features of in born errors pertaining to the salvage enzyme's deficiency that leads to NEE and other pathologies. We also present perspective on vitamin B6 treatment for these disorders, along with attempts to develop zebrafish model to study the NEE syndrome in vivo.
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Affiliation(s)
- Mohini S Ghatge
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA; Institute for Structural Biology, Drug Discovery, and Development, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Mohammed Al Mughram
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA; Institute for Structural Biology, Drug Discovery, and Development, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Abdelsattar M Omar
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, King Abdulaziz University, Alsulaymanyah, Jeddah, 21589, Saudi Arabia; Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Al-Azhar University, Cairo, 11884, Egypt
| | - Martin K Safo
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA; Institute for Structural Biology, Drug Discovery, and Development, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA.
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26
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Seefried L, Kishnani PS, Moseley S, Denker AE, Watsky E, Whyte MP, Dahir KM. Pharmacodynamics of asfotase alfa in adults with pediatric-onset hypophosphatasia. Bone 2021; 142:115664. [PMID: 32987199 DOI: 10.1016/j.bone.2020.115664] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 09/11/2020] [Accepted: 09/23/2020] [Indexed: 12/31/2022]
Abstract
BACKGROUND Hypophosphatasia (HPP) is the rare, inherited, metabolic bone disease characterized by low activity of the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP) leading to excess extracellular inorganic pyrophosphate (PPi) and pyridoxal 5'-phosphate (PLP). Asfotase alfa is the human recombinant enzyme-replacement therapy that replaces deficient TNSALP. However, there is limited information concerning the appropriate dose of asfotase alfa for adult patients with pediatric-onset HPP. Thus, we evaluated the pharmacodynamics and safety/tolerability of different doses of asfotase alfa in such patients. METHODS This 13-week, Phase 2a, open-label study enrolled adults (aged ≥18 years) with pediatric-onset HPP. They were randomized 1:1:1 to receive a single subcutaneous dose of asfotase alfa (0.5, 2.0, or 3.0 mg/kg) at Week 1, then 3 times per week (ie, 1.5, 6.0, or 9.0 mg/kg/wk) starting at Week 3 for 7 weeks. Key outcome measures included change from Baseline to before the third dose during Week 9 (trough) in plasma PPi (primary outcome measure) and PLP (secondary outcome measure). RESULTS Twenty-seven adults received asfotase alfa 0.5 (n = 8), 2.0 (n = 10), and 3.0 (n = 9) mg/kg; all completed the study. Median (range) age was 45 (18-77) years; most patients were white (96%) and female (59%). Median plasma PPi and PLP concentrations decreased from Baseline to Week 9 in all 3 cohorts. Differences in least squares mean (LSM) changes in PPi were significant with 2.0 mg/kg (p = 0.0008) and 3.0 mg/kg (p < 0.0001) vs. 0.5 mg/kg. Differences in LSM changes in PLP were also significant for 2.0 mg/kg (p = 0.0239) and 3.0 mg/kg (p = 0.0128) vs. 0.5 mg/kg. Injection site reactions were the most frequent treatment-emergent adverse event (78%), showing increasing frequency with increasing dose. CONCLUSIONS Adults with pediatric-onset HPP receiving asfotase alfa at 6.0 mg/kg/wk (the recommended dose) or 9.0 mg/kg/wk had greater reductions in circulating PPi and PLP concentrations compared with a lower dose of 1.5 mg/kg/wk. TRIAL REGISTRATION Clinicaltrials.gov identifier NCT02797821.
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Affiliation(s)
- Lothar Seefried
- Orthopedic Department, University of Würzburg, Würzburg, Bavaria, Germany.
| | - Priya S Kishnani
- Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | | | | | - Eric Watsky
- Alexion Pharmaceuticals, Inc., Boston, MA, USA
| | - Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children-St. Louis, St. Louis, MO, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St Louis, MO, USA
| | - Kathryn M Dahir
- Program for Metabolic Bone Disorders at Vanderbilt, Division of Diabetes and Endocrinology, Vanderbilt University Medical Center, Nashville, TN, USA
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Durrough C, Colazo JM, Simmons J, Hu JR, Hudson M, Black M, de Riesthal M, Dahir K. Characterization of physical, functional, and cognitive performance in 15 adults with hypophosphatasia. Bone 2021; 142:115695. [PMID: 33069919 DOI: 10.1016/j.bone.2020.115695] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 09/08/2020] [Accepted: 10/12/2020] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Given the small but growing body of literature related to physical functioning and the scarce data related to fine motor and cognitive functioning in adults with hypophosphatasia (HPP), our objective was to characterize physical, functional, and cognitive performance in adults with HPP. A future objective is to utilize this characterization to develop guidelines for evaluation by physical therapists (PT), occupational therapists (OT), and speech-language pathologists (SLP). METHOD We evaluated physical, functional, and cognitive performance in 15 adults with HPP through standardized assessments of mobility, balance, fine motor control, activities of daily living, cognition, and self-reported measures of health-related quality of life, fatigue, depression, and anxiety. The median age at enrollment was 44 years (range 26-79 years). Among the participants, 11 (73%) were women. Five participants (33%) were on enzyme replacement therapy. RESULTS Compared with the general population, HPP participants traveled shorter distances on the Six-Minute Walk Test (420 m (m) [SD: 132] vs 620 m [SD: 49], p < 0.00005), had slower gait on the 10-Meter Walk Test [HPP men (3.71 ft/s (f/s) [SD: 0.77] vs 4.70 f/s [SD: 0.14], p < 0.00005) and HPP women (3.39 f/s [SD: 0.67] vs 4.56 f/s [SD: 0.09], p < 0.00005)]. HPP participants had decreased upper extremity (UE) dexterity by Nine Hole Peg Test [right UE in HPP men (22.7 s (s) [SD: 2.3] vs 19.0 s [SD: 3.9], p = 0.03), left UE in HPP men (23.3 s [SD: 0.7] vs 19.8 s [SD: 3.7], p = 0.03), right UE in HPP women (19.8 s [SD: 2.0] vs 17.7 s [SD: 3.2], p = 0.01), and left UE in HPP women (21.1 s [SD: 2.5] vs 18.9 s[SD: 3.4], p = 0.02)], and some had abnormally slow bilateral UE reaction times via Dynavision (0.9 s [0.85,0.96], functional speed <1.15 s). On the Short Form-36 (SF36), HPP patients reported worse energy/fatigue (30.4 [SD 22.7] vs 52.2 [SD: 22.4], p = 0.0001), social functioning (54.5 [SD: 34.2] vs 78.8 [SD: 25.5], p = 0.0002), pain (46.1 [SD: 27.3] vs 70.8 [SD: 25.5], p = 0.0001), general health (36.8 [SD: 24.0] vs 57.0 [SD: 21.1], p = 0.0002), and health change i.e. perception of health improvement (32.1 [SD: 15.3] vs 59.1 [SD: 23.1], p < 0.00005) than the general population. Fatigue Severity Scale scores were well above the median for a healthy population (5.21 [SD: 1.8] vs 2.3 [SD: 1.21], p < 0.00005), indicating significant fatigue. HPP participants had significantly higher DASS scores for depression (8.5 [SD: 6.5] vs 5.0 [SD: 7.5], p = 0.02), anxiety (7.9 [SD: 6.7] vs 3.4 [SD: 5.1], p = 0.00009), and stress (14.7 [SD: 12.4] vs 8.1 [SD: 8.4], p = 0.0003) compared to the general population. CONCLUSION Objective functional assessments demonstrated defects in physical functioning, including decreased ability to walk distances, slow gait speed, and diminished ability to repeatedly rise from a sitting position. In addition, participants self-reported significant limitations due to physical dysfunction. Decreased upper extremity dexterity may indicate problems with activities of daily living and delayed reaction times can have safety implications. Some patients with HPP have increased difficulties with depression, anxiety, and stress. PT, OT, and SLP specialists can aid in establishing baseline assessment of impairment and objective metrics for assessing efficacy of treatment.
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Affiliation(s)
| | - Juan M Colazo
- Medical Scientist Training Program, Vanderbilt University and Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Jill Simmons
- Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jiun-Ruey Hu
- Vanderbilt University Medical Center, Nashville, TN, USA
| | - Margaret Hudson
- Vanderbilt Pi Beta Phi Rehabilitation Institute, Nashville, TN, USA
| | - Margo Black
- Vanderbilt University Medical Center, Nashville, TN, USA
| | | | - Kathryn Dahir
- Vanderbilt University Medical Center, Nashville, TN, USA.
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Tissue-Nonspecific Alkaline Phosphatase-A Gatekeeper of Physiological Conditions in Health and a Modulator of Biological Environments in Disease. Biomolecules 2020; 10:biom10121648. [PMID: 33302551 PMCID: PMC7763311 DOI: 10.3390/biom10121648] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/30/2020] [Accepted: 12/05/2020] [Indexed: 12/15/2022] Open
Abstract
Tissue-nonspecific alkaline phosphatase (TNAP) is a ubiquitously expressed enzyme that is best known for its role during mineralization processes in bones and skeleton. The enzyme metabolizes phosphate compounds like inorganic pyrophosphate and pyridoxal-5′-phosphate to provide, among others, inorganic phosphate for the mineralization and transportable vitamin B6 molecules. Patients with inherited loss of function mutations in the ALPL gene and consequently altered TNAP activity are suffering from the rare metabolic disease hypophosphatasia (HPP). This systemic disease is mainly characterized by impaired bone and dental mineralization but may also be accompanied by neurological symptoms, like anxiety disorders, seizures, and depression. HPP characteristically affects all ages and shows a wide range of clinical symptoms and disease severity, which results in the classification into different clinical subtypes. This review describes the molecular function of TNAP during the mineralization of bones and teeth, further discusses the current knowledge on the enzyme’s role in the nervous system and in sensory perception. An additional focus is set on the molecular role of TNAP in health and on functional observations reported in common laboratory vertebrate disease models, like rodents and zebrafish.
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Kato M, Hattori T, Shimizu T, Ninagawa K, Izumihara R, Nomoto H, Tanimura K, Atsumi T. Intrafamilial phenotypic distinction of hypophosphatasia with identical tissue nonspecific alkaline phosphatase gene mutation: a family report. J Bone Miner Metab 2020; 38:903-907. [PMID: 32772198 DOI: 10.1007/s00774-020-01137-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 07/30/2020] [Indexed: 10/23/2022]
Abstract
Hypophosphatasia (HPP) is caused by mutations in the tissue nonspecific alkaline phosphatase (TNSALP) gene in an autosomal recessive or dominant manner and characterized by defective mineralization of bone and low serum ALP levels. In this report, we present a family with HPP mother (case 1) and HPP child (case 2) who have identical TNSALP gene mutation (c.1015G>A p.Gly339Arg heterozygous mutation) but distinct clinical phenotypes. Whereas case 1 appeared to be asymptomatic despite extremely low levels of serum ALP, case 2 had several HPP-related symptoms, such as tooth loss, fractures, short stature, with slightly decreased ALP levels. Upon the diagnosis of HPP, case 1 discontinued denosumab, which was used to treat her rheumatoid arthritis, concerning the risk of atypical femoral fractures. The clinical course of this family was suggestive in a genotype-phenotype imbalance in HPP, the underdiagnosis of HPP in adults, and the risk of atypical femoral fractures using bone resorption inhibitors.
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Affiliation(s)
- Masaru Kato
- Department of Rheumatology, Endocrinology and Nephrology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-Ku, Sapporo, 060-8638, Japan.
| | | | - Tomohiro Shimizu
- Department of Orthopedic Surgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Keita Ninagawa
- Department of Rheumatology, Endocrinology and Nephrology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-Ku, Sapporo, 060-8638, Japan
| | - Rimi Izumihara
- Department of Rheumatology, Endocrinology and Nephrology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-Ku, Sapporo, 060-8638, Japan
| | - Hiroshi Nomoto
- Department of Rheumatology, Endocrinology and Nephrology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-Ku, Sapporo, 060-8638, Japan
| | | | - Tatsuya Atsumi
- Department of Rheumatology, Endocrinology and Nephrology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-Ku, Sapporo, 060-8638, Japan
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30
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Seefried L, Dahir K, Petryk A, Högler W, Linglart A, Martos-Moreno GÁ, Ozono K, Fang S, Rockman-Greenberg C, Kishnani PS. Burden of Illness in Adults With Hypophosphatasia: Data From the Global Hypophosphatasia Patient Registry. J Bone Miner Res 2020; 35:2171-2178. [PMID: 32654183 DOI: 10.1002/jbmr.4130] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 06/25/2020] [Accepted: 07/04/2020] [Indexed: 12/19/2022]
Abstract
Hypophosphatasia (HPP) is a rare, inherited, metabolic disease caused by deficient tissue non-specific alkaline phosphatase activity. This study aims to assess patient-reported pain, disability and health-related quality of life (HRQoL) in a real-world cohort of adults with HPP who were not receiving asfotase alfa during the analysis. Adults (≥18 years old) with HPP (confirmed by ALPL gene mutation and/or low serum alkaline phosphatase activity for age/sex) were identified from the Global HPP Registry (NCT02306720). Demographics, clinical characteristics, and data on patient-reported pain, disability, and HRQoL (assessed by Brief Pain Inventory Short Form [BPI-SF], Health Assessment Questionnaire Disability Index [HAQ-DI], and 36-Item Short-Form Health Survey version 2 [SF-36v2], respectively) were stratified by pediatric- and adult-onset HPP and summarized descriptively. Of the 304 adults included (median [min, max] age 48.6 [18.8, 79.8] years; 74% women), 45% had adult-onset HPP and 33% had pediatric-onset HPP (unknown age of onset, 22%). Of those with data, 38% had experienced ≥5 HPP manifestations and 62% had a history of ≥1 fracture/pseudofracture. Median (Q1, Q3) BPI-SF scores were 3.5 (1.5, 5.3) for pain severity and 3.3 (0.9, 6.2) for pain interference. Median (Q1, Q3) disability on the HAQ-DI was 0.3 (0.0, 0.7). Median (Q1, Q3) physical and mental component summary scores on the SF-36v2 were 42.4 (32.7, 49.9) and 45.3 (36.3, 54.8), respectively. Greater numbers of HPP manifestations experienced/body systems affected correlated significantly with poorer scores on the BPI-SF, HAQ-DI, and SF-36v2 (all p < 0.05). No significant differences between adults with pediatric- and adult-onset HPP were observed for patient-reported outcomes, except for disability and the BPI-SF question "pain at its worst," which were significantly higher among adults with pediatric- versus adult-onset HPP (p = 0.03 and 0.04, respectively). These data from the Global HPP Registry show that adults with HPP have a substantial burden of illness that is associated with reduced patient-reported HRQoL, regardless of age of disease onset. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Lothar Seefried
- Orthopedic Department, University of Würzburg, Würzburg, Germany
| | - Kathryn Dahir
- Vanderbilt University Medical Center, Nashville, TN, USA
| | - Anna Petryk
- Alexion Pharmaceuticals, Inc., Boston, MA, USA
| | - Wolfgang Högler
- Department of Pediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Agnès Linglart
- AP-HP Paris-Saclay, Endocrinology and Diabetes for Children, Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Filière OSCAR, Paris, France
| | - Gabriel Ángel Martos-Moreno
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, IIS La Princesa, Madrid, Spain.,Department of Pediatrics, Universidad Autónoma de Madrid, Madrid, Spain.,CIBERobn, ISCIII, Madrid, Spain
| | - Keiichi Ozono
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Shona Fang
- Alexion Pharmaceuticals, Inc., Boston, MA, USA
| | | | - Priya S Kishnani
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
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Li XY, Wan XH, Chen L, Guo WH, Wang L. A compound heterozygous ALPL variant in a patient with dystonia-parkinsonism and hypointensity in basal ganglia: A case report. Parkinsonism Relat Disord 2020; 78:184-185. [PMID: 32956941 DOI: 10.1016/j.parkreldis.2020.07.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 07/20/2020] [Accepted: 07/29/2020] [Indexed: 11/17/2022]
Affiliation(s)
- Xin-Yao Li
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, 100730, China
| | - Xin-Hua Wan
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, 100730, China
| | - Lin Chen
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, 100730, China
| | - Wei-Hong Guo
- Department of Vasculocardiology, Fuwai Hospital, Chinese Academy of Medical Sciences, 100037, China
| | - Lin Wang
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, 100730, China.
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Investigation of alpl expression and Tnap-activity in zebrafish implies conserved functions during skeletal and neuronal development. Sci Rep 2020; 10:13321. [PMID: 32770041 PMCID: PMC7414108 DOI: 10.1038/s41598-020-70152-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 07/21/2020] [Indexed: 12/23/2022] Open
Abstract
Hypophosphatasia (HPP) is a rare genetic disease with diverse symptoms and a heterogeneous severity of onset with underlying mutations in the ALPL gene encoding the ectoenzyme Tissue-nonspecific alkaline phosphatase (TNAP). Considering the establishment of zebrafish (Danio rerio) as a new model organism for HPP, the aim of the study was the spatial and temporal analysis of alpl expression in embryos and adult brains. Additionally, we determined functional consequences of Tnap inhibition on neural and skeletal development in zebrafish. We show that expression of alpl is present during embryonic stages and in adult neuronal tissues. Analyses of enzyme function reveal zones of pronounced Tnap-activity within the telencephalon and the mesencephalon. Treatment of zebrafish embryos with chemical Tnap inhibitors followed by axonal and cartilage/mineralized tissue staining imply functional consequences of Tnap deficiency on neuronal and skeletal development. Based on the results from neuronal and skeletal tissue analyses, which demonstrate an evolutionary conserved role of this enzyme, we consider zebrafish as a promising species for modeling HPP in order to discover new potential therapy strategies in the long-term.
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Genest F, Rak D, Petryk A, Seefried L. Physical Function and Health-Related Quality of Life in Adults Treated With Asfotase Alfa for Pediatric-Onset Hypophosphatasia. JBMR Plus 2020; 4:e10395. [PMID: 32995696 PMCID: PMC7507107 DOI: 10.1002/jbm4.10395] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 07/02/2020] [Accepted: 07/13/2020] [Indexed: 12/25/2022] Open
Abstract
Hypophosphatasia (HPP) is a rare, inherited, metabolic disease characterized by tissue-nonspecific alkaline phosphatase deficiency resulting in musculoskeletal and systemic clinical manifestations. This observational study evaluated the effectiveness of enzyme replacement therapy with asfotase alfa on physical function and health-related quality of life (HRQoL) among adults with pediatric-onset HPP who received asfotase alfa for 12 months at a single center (ClinicalTrial.gov no.: NCT03418389). Primary outcomes evaluated physical function with the 6-minute walk test (6MWT), timed up-and-go (TUG) test, Short Physical Performance Battery (SPPB), and handheld dynamometry (HHD). Secondary outcome measures included the Lower Extremity Functional Scale (LEFS), pain prevalence/intensity, and pain medication use; HRQoL was evaluated using the 36-Item Short-Form Health Survey version 2 (SF-36v2). Safety data were collected throughout the study. All 14 patients (11 women) had compound heterozygous ALPL gene mutations and ≥1 HPP bone manifestation, including history of ≥1 fracture. Mean (min, max) age was 51 (19 to 78) years. From baseline to 12 months of treatment, median 6MWT distance increased from 267 m to 320 m (n = 13; p = 0.023); median TUG test time improved from 14.4 s to 11.3 s (n = 9; p = 0.008). Specific components of the SPPB also improved significantly: median 4-m gait speed increased from 0.8 m/s to 1.1 m/s (n = 10; p = 0.007) and median repeated chair-rise time improved from 22 s to 13 s (n = 9; p = 0.008). LEFS score improved from 24 points to 53 points (n = 10; p = 0.002). Improvements in HHD were not clinically significant. SF-36v2 Physical Component Score (PCS) improved after 12 months of treatment (n = 9; p = 0.010). Pain level did not change significantly from baseline to 12 months of treatment. There were significant improvements on chair-rise time and SF-36v2 PCS by 3 months, and on TUG test time after 6 months. No new safety signals were identified. These results show the real-world effectiveness of asfotase alfa in improving physical functioning and HRQoL in adults with pediatric-onset HPP. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Franca Genest
- Orthopedic Department University of Würzburg Würzburg Germany
| | - Dominik Rak
- Orthopedic Department University of Würzburg Würzburg Germany
| | | | - Lothar Seefried
- Orthopedic Department University of Würzburg Würzburg Germany
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Kuehn K, Hahn A, Seefried L. Mineral Intake and Clinical Symptoms in Adult Patients with Hypophosphatasia. J Clin Endocrinol Metab 2020; 105:5851912. [PMID: 32502243 DOI: 10.1210/clinem/dgaa324] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 06/02/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND Hypophosphatasia (HPP) is a rare inherited metabolic disorder characterized by deficient activity of the tissue-nonspecific alkaline phosphatase entailing impaired turnover of phosphorus metabolites. Dietary mineral intake is suspected to influence clinical symptoms of HPP, but scientific evidence is missing. METHODS Cross-sectional matched-pairs study collecting comprehensive data on nutrient intake in 20 HPP patients and 20 unaffected, age- and gender-matched controls. Dietary information and clinical symptoms were documented in detail over 7 consecutive days using structured diaries. RESULTS Baseline data and type of energy-supplying nutrients were balanced between both groups. Median nutritional intake of phosphorus and calcium were significantly lower in HPP patients versus controls, which is partially attributable to lower energy consumption in HPP patients. Differences regarding phosphorus and calcium (Ca/P) ratio and uptake of magnesium, zinc, and vitamin B6 were not statistically significant. Both high (≥ 1375 mg/d) and low intakes (< 1100 mg/d) of phosphorus were significantly associated with an increased frequency of neuropsychiatric symptoms (P = 0.02). Similarly, very high and very low intake of calcium was significantly associated with musculoskeletal (P < 0.01), gastrointestinal (P = 0.02), and neuropsychiatric (P < 0.001) symptoms. An increased Ca/P ratio was associated with increased tiredness/fatigue (P < 0.01), whereas a decreased Ca/P was associated with gastrointestinal issues (P = 0.01). CONCLUSION Phosphorus and calcium intake seem reduced in HPP patients along with reduced total energy consumption. Particularly high as well as very low absolute or unbalanced phosphorus and calcium intake are associated with an increased frequency of clinical symptoms.
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Affiliation(s)
- Katinka Kuehn
- Faculty of Natural Science, Institute of Food Science and Human Nutrition, Leibniz University Hannover, Hannover, Germany
| | - Andreas Hahn
- Faculty of Natural Science, Institute of Food Science and Human Nutrition, Leibniz University Hannover, Hannover, Germany
| | - Lothar Seefried
- Clinical Trial Unit, Orthopedic Institute, Koenig-Ludwig-Haus, University of Wuerzburg, Wuerzburg, Germany
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Bangura A, Wright L, Shuler T. Hypophosphatasia: Current Literature for Pathophysiology, Clinical Manifestations, Diagnosis, and Treatment. Cureus 2020; 12:e8594. [PMID: 32676235 PMCID: PMC7362651 DOI: 10.7759/cureus.8594] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/12/2020] [Indexed: 12/11/2022] Open
Abstract
Hypophosphatasia (HPP) is a rare inherited bone disorder identified by impaired bone mineralization. There are seven subtypes of HPP mainly characterized by their age of onset. These subtypes consist of perinatal (prenatal) benign, perinatal lethal, infantile, childhood, adult, odontohypophosphatasia, and pseudohypophosphatasia. Due to limited awareness of the condition, either misdiagnosis or delayed diagnosis is common. Furthermore, the condition is frequently treated with contraindicated drugs. This literature illustrates the most recent findings on the etiology, pathophysiology, clinical manifestations, diagnosing, and treatment for HPP and its subtypes. The etiology of the disease consists of loss-of-function mutations of the ALPL gene on chromosome one, which encodes for tissue nonspecific isoenzyme of alkaline phosphatase (TNAP). A decrease of TNAP reduces inorganic phosphate (Pi) for bone mineralization and allows for an increase in inorganic pyrophosphate (PPi) and phosphorylated osteopontin (p-OPN), which further reduces bone mineralization. The combination of these processes softens bone and mediates a clinical presentation similar to rickets/osteomalacia. HPP has an additional wide range of clinical features depending on its subtype. Although a concrete diagnostic guideline has not yet been established, many studies have supported a similar method of identifying HPP. Clinical features, radiological findings, and/or biomarker levels of the disorder should raise suspicion and encourage the inclusion of HPP as a differential diagnosis. Biomarkers, especially alkaline phosphatase (ALP), are major contributors to diagnosis. However, genetic testing is done for definitive diagnosis. The primary treatment for HPP is the reintroduction of TNAP as a recombinant enzyme called asfotase alfa. There are additional pharmaceutical treatments and in some cases, surgical intervention may be indicated. Pharmaceutical therapies such as bisphosphonates, denosumab, potent antiresorptive agents, and vitamin D are contraindicated in adults with HPP. We hope to raise awareness for HPP in order to prevent delayed diagnosis or misdiagnosis. We plan to encourage appropriate care and avoid treatments that may be contraindicating. We also encourage the development of a diagnostic guideline that will promote a consistently favorable patient prognosis.
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Affiliation(s)
- Abdulai Bangura
- Department of Research, Trinity School of Medicine, Ratho Mill, VCT
| | - Lisa Wright
- Department of Orthopaedics, Carilion Clinic, Roanoke, USA
| | - Thomas Shuler
- Department of Orthopaedics, Carilion Clinic, Roanoke, USA
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Chida-Naomiya R, Shimura M, Nagao R, Kumada A, Kawashima H. Hearing impairment improved after treatment with asfotase alfa in a case of perinatal hypophosphatasia. Mol Genet Metab Rep 2020; 24:100612. [PMID: 32547926 PMCID: PMC7284058 DOI: 10.1016/j.ymgmr.2020.100612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/25/2020] [Accepted: 05/25/2020] [Indexed: 01/07/2023] Open
Abstract
Hearing impairment is a neurological symptom of hypophosphatasia (HPP), which leads to a reduced quality of life. However, the pathomechanism of hearing impairment and the effects of asfotase alfa enzyme replacement therapy on hearing function in HPP have not been clarified. Here we report a case and present clinical data of a patient with perinatal HPP whose hearing impairment improved after asfotase alfa treatment.
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Affiliation(s)
- Rie Chida-Naomiya
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan
| | - Masaru Shimura
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan
| | - Ryuhei Nagao
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan
| | - Atsushi Kumada
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan
| | - Hisashi Kawashima
- Department of Pediatrics and Adolescent Medicine, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan
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Hypophosphatasie – eine klinisch und genetisch variable Erkrankung. MED GENET-BERLIN 2019. [DOI: 10.1007/s11825-019-00271-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Zusammenfassung
Die Hypophosphatasie (HPP) ist eine erbliche metabolische Multisystemerkrankung, deren klinische Hauptcharakteristika Mineralisierungsstörungen von Knochen und Zähnen sowie Muskel- und Gelenkschmerzen sind. Die klinische Symptomatik ist vom Erkrankungsalter abhängig und gestaltet sich sowohl interindividuell als auch intrafamiliär sehr variabel. Es werden sechs Unterformen der HPP abgegrenzt, wobei die Übergänge fließend sind. Sie reichen von der schweren perinatalen Form, die früher aufgrund fehlender Skelettmineralisierung meist tödlich war, bis hin zur adulten Form mit typischen Symptomen wie Frakturheilungsstörungen oder Stressfrakturen. Unspezifische Symptome wie Muskelschmerzen und -schwäche, Migräne oder Depressionen können ebenfalls Teil der HPP sein. Während schwere Formen mit einer Prävalenz zwischen 1/100.000 und 1/300.000 selten sind, kommen milde Formen der HPP deutlich häufiger vor. Perinatale und frühkindliche Formen sind meist autosomal-rezessiv vererbt, hingegen werden später auftretende Formen autosomal-rezessiv oder -dominant vererbt. Ursache der HPP ist eine reduzierte oder fehlende Aktivität der gewebeunspezifischen alkalischen Phosphatase (AP), welche durch das ALPL-Gen kodiert wird. Laborchemisch lassen sich im Serum eine alters- und geschlechtsspezifisch erniedrigte AP-Aktivität und eine konsekutive Erhöhung der AP-Substrate, z. B. des Pyridoxal-5-Phosphats (PLP), feststellen. Seit der Erstbeschreibung der Erkrankung 1948 haben sich die Diagnostik und Therapie der HPP dramatisch verbessert. Vor 4 Jahren ist eine Enzymersatztherapie mit Asfotase alfa (Strensiq®) für schwer betroffene HPP-Patienten mit Beginn der Erkrankung vor dem 18. Lebensjahr zugelassen worden. Dieser Artikel gibt einen Überblick über das breite klinische Spektrum der HPP, pathophysiologische Hintergründe, die laborchemische und molekulargenetische Diagnostik sowie gegenwärtige Therapieoptionen und deren Behandlungsindikationen.
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