1
|
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.
Collapse
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.
| |
Collapse
|
2
|
Tachikawa K, Yamazaki M, Michigami T. A unique case of childhood hypophosphatasia caused by a novel heterozygous 51-bp in-frame deletion in the ALPL gene. Clin Pediatr Endocrinol 2023; 32:180-187. [PMID: 37362163 PMCID: PMC10288296 DOI: 10.1297/cpe.2023-0019] [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: 03/13/2023] [Accepted: 04/18/2023] [Indexed: 06/28/2023] Open
Abstract
Hypophosphatasia (HPP) is caused by inactivating variants of the ALPL gene, which encodes tissue non-specific alkaline phosphatase (TNSALP). Among the six subtypes of HPP, childhood HPP presents after 6 months and before 18 yr of age, and is inherited in both autosomal dominant and autosomal recessive manners. Patients with childhood HPP have variable symptoms, including rickets-like bone changes, low bone mineral density (BMD), short stature, muscle weakness, craniosynostosis, and premature loss of deciduous teeth. Here, we describe a 7-yr-old boy with childhood HPP who showed short stature, impaired ossification of the carpal bones, and low BMD. Genetic testing identified a novel heterozygous 51-bp in-frame deletion in the ALPL gene (c.1482_1532del51), leading to the lack of 17 amino acids between Gly495 and Leu511 (p.Gly495_Leu511del). In vitro transfection experiments revealed the loss of enzymatic activity and the dominant-negative effect of the TNSALP[p.Gly495_Leu511del] variant; thus, the patient was diagnosed as having autosomal dominant HPP. The TNSALP[p.Gly495_Leu511del] variant was localized to the plasma membrane as was the wild-type TNSALP (TNSALP[WT]): however, co-immunoprecipitation experiments suggested a reduced dimerization between TNSALP[p.Gly495_Leu511del] and TNSALP[WT]. This case expands the variable clinical manifestation of childhood HPP and sheds light on the molecular bases underlying the dominant-negative effects of some TNSALP variants.
Collapse
Affiliation(s)
- Kanako Tachikawa
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, Osaka, Japan
| | - Miwa Yamazaki
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, Osaka, Japan
| | - Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, Osaka, Japan
| |
Collapse
|
3
|
Abstract
Hypophosphatasia (HPP) is a rare inherited systemic metabolic disease caused by mutations in the tissue-nonspecific alkaline phosphatase (TNSALP) gene. TNSALP is expressed in the liver, kidney and bone, and its substrates include TNSALP inorganic pyrophosphate, pyridoxal-5'-phosphate (PLP)/vitamin B6 and phosphoethanolamine (PEA). Autosomal recessive and dominant forms of the disease result in a range of clinical entities. Major hallmarks are low alkaline phosphatase (ALP) and elevated PLP and PEA levels. Very severe infantile forms of HPP cause premature death as a result of respiratory insufficiency and also present with hypo-mineralisation leading to deformed limbs with, in some cases, the near-absence of bones and skull altogether. Respiratory failure, rib fractures and seizures due to vitamin B6 deficiency are indicative of a poor prognosis. Craniosynostosis is frequent. HPP leads to an unusual presentation of rickets with high levels of calcium and phosphorus, resulting in hypercalciuria, nephrocalcinosis and low ALP levels. Hypercalcaemic crisis, failure to thrive and growth retardation are concerns in infants. Fractures are common in both infantile and adult forms of the disease, concomitantly occurring with unexplained chronic pain and fatigue. Dental clinical presentations, which include the premature loss of teeth, are also commonly found in HPP and specifically manifest as odontohypophosphatasia. A novel enzyme therapy for human HPP, asfotase alfa, which is specifically targeted to mineralised tissues, has been developed in the past decades. While this treatment seems very promising, especially for infantile HPP, many questions regarding its long-term effects, the management of treatment, and any potential secondary adverse effects remain unresolved.
Collapse
|
4
|
Akiyama T, Kubota T, Ozono K, Michigami T, Kobayashi D, Takeyari S, Sugiyama Y, Noda M, Harada D, Namba N, Suzuki A, Utoyama M, Kitanaka S, Uematsu M, Mitani Y, Matsunami K, Takishima S, Ogawa E, Kobayashi K. Pyridoxal 5'-phosphate and related metabolites in hypophosphatasia: Effects of enzyme replacement therapy. Mol Genet Metab 2018; 125:174-180. [PMID: 30049651 DOI: 10.1016/j.ymgme.2018.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 07/12/2018] [Accepted: 07/12/2018] [Indexed: 10/28/2022]
Abstract
OBJECTIVE To investigate the utility of serum pyridoxal 5'-phosphate (PLP), pyridoxal (PL), and 4-pyridoxic acid (PA) as a diagnostic marker of hypophosphatasia (HPP) and an indicator of the effect of, and patient compliance with, enzyme replacement therapy (ERT), we measured PLP, PL, and PA concentrations in serum samples from HPP patients with and without ERT. METHODS Blood samples were collected from HPP patients and serum was frozen as soon as possible (mostly within one hour). PLP, PL, and PA concentrations were analyzed using high-performance liquid chromatography with fluorescence detection after pre-column derivatization by semicarbazide. We investigated which metabolites are associated with clinical phenotypes and how these metabolites change with ERT. RESULTS Serum samples from 20 HPP patients were analyzed. The PLP-to-PL ratio and PLP concentration were elevated in all HPP patients. They correlated negatively with serum alkaline phosphatase (ALP) activity and showed higher values in more severe phenotypes (perinatal severe and infantile HPP) compared with other phenotypes. PL concentration was reduced only in perinatal severe HPP. ERT reduced the PLP-to-PL ratio to mildly reduced or low-normal levels and the PLP concentration was reduced to normal or mildly elevated levels. Urine phosphoethanolamine (PEA) concentration did not return to normal levels with ERT in most patients. CONCLUSIONS The serum PLP-to-PL ratio is a better indicator of the effect of ERT for HPP than serum PLP and urine PEA concentrations, and a PLP-to-PL ratio of <4.0 is a good indicator of the effect of, and patient compliance with, ERT.
Collapse
Affiliation(s)
- Tomoyuki Akiyama
- Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
| | - Takuo Kubota
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Toshimi Michigami
- Department of Bone and Mineral Research, Osaka Women's and Children's Hospital, Osaka, Japan
| | - Daisuke Kobayashi
- Department of Food and Chemical Toxicology, School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Hokkaido, Japan
| | - Shinji Takeyari
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Yuichiro Sugiyama
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Aichi, Japan
| | - Masahiro Noda
- Department of Pediatrics, Showa General Hospital, Tokyo, Japan
| | - Daisuke Harada
- Department of Pediatrics, Osaka Hospital, Japan Community Healthcare Organization (JCHO), Osaka, Japan
| | - Noriyuki Namba
- Department of Pediatrics, Osaka Hospital, Japan Community Healthcare Organization (JCHO), Osaka, Japan
| | - Atsushi Suzuki
- Department of Neonatology and Pediatrics, Nagoya City University Graduate School of Medical Sciences, Aichi, Japan
| | - Maiko Utoyama
- Department of Pediatrics, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Sachiko Kitanaka
- Department of Pediatrics, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Mitsugu Uematsu
- Department of Pediatrics, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Yusuke Mitani
- Department of Pediatrics, Kanazawa University Hospital, Ishikawa, Japan
| | - Kunihiro Matsunami
- Department of Pediatrics, Gifu Prefectural General Medical Center, Gifu, Japan
| | | | - Erika Ogawa
- Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, Japan
| | - Katsuhiro Kobayashi
- Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| |
Collapse
|
5
|
|
6
|
Deng S, Scott D, Garg U. Quantification of Five Clinically Important Amino Acids by HPLC-Triple TOF™ 5600 Based on Pre-column Double Derivatization Method. Methods Mol Biol 2016; 1378:47-53. [PMID: 26602116 DOI: 10.1007/978-1-4939-3182-8_6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Phenylalanine, tyrosine, glycine, cystine, and phosphoethanolamine are commonly measured amino acids in various physiological fluids to diagnose or follow-up various inborn errors of metabolism. The gold standard method for the amino acids quantitation has been ion exchange chromatography with ninhydrin post-column derivatization. However, this method is very laborious and time consuming. In recent years, liquid-chromatography mass spectrometry is being increasingly used for the assay of amino acids. Pre-column butyl derivatization with reverse phase chromatography has been widely used for mass spectrometry analysis of amino acids. Phosphoethanolamine is not butylated and cannot be measured by this method. Nevertheless, phosphoethanolamine can be dansyl-derivatized using dansyl chloride. We developed a double derivatization method by using butanol and dansyl chloride to derivatize carboxylic and amino groups separately, and then combining the derivatives to simultaneously measure these five amino acids using TOF-MS scan. Stable isotope-labeled internal standards were used.
Collapse
Affiliation(s)
- Shuang Deng
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospitals and Clinics, 2401 Gillham Road, Kansas City, MO, 64108, USA
| | - David Scott
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospitals and Clinics, 2401 Gillham Road, Kansas City, MO, 64108, USA
| | - Uttam Garg
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospitals and Clinics, 2401 Gillham Road, Kansas City, MO, 64108, USA.
- University of Missouri School of Medicine, Kansas City, MO, USA.
| |
Collapse
|
7
|
Abstract
Hypophosphatasia (HPP) is due to mutations of the tissue non-specific alkaline phosphatase (TNAP) gene expressed in the liver, kidney, and bone. TNAP substrates include inorganic pyrophosphate cleaved into inorganic phosphate (Pi) in bone, pyridoxal-5'-phosphate (PLP), the circulating form of vitamin B6, and phosphoethanolamine (PEA). As an autosomal recessive or dominant disease, HPP results in a range of clinical forms. Its hallmarks are low alkaline phosphatase (AP) and elevated PLP and PEA levels. Perinatal HPP may cause early death with respiratory insufficiency and hypomineralization resulting in deformed limbs and sometimes near-absence of bones and skull. Infantile HPP is diagnosed before 6 months of life. Respiratory failure, rib fractures and seizures due to vitamin B6 deficiency in the brain indicate poor prognosis. Craniosynostosis is frequent. Unlike in other forms of rickets, calcium and phosphorus are not decreased, resulting in hypercalciuria and nephrocalcinosis. Hypercalcemic crisis may occur. Failure to thrive and growth retardation are concerns. In infantile and adult forms of HPP, non-traumatic fractures may be the prominent manifestation, with otherwise unexplained chronic pain. Progressive myopathy has been described. Dental manifestations with early loss of teeth are usual in HPP and in a specific form, odontohypophosphatasia. HPP has been studied in knock-out mice models which mimic its severe form. Animal models have made a major contribution to the development of an original enzyme therapy for human infantile HPP, which is however essentially targeted at mineralized tissues. Better knowledge of its extraskeletal manifestations, including pain and neurological symptoms, is therefore required.
Collapse
Affiliation(s)
- Jean Pierre Salles
- Unité d'Endocrinologie Maladies Osseuses, Hôpital Des Enfants, CHU de Toulouse and Inserm UMR 1043 UPS, Toulouse Cedex, France,
| |
Collapse
|