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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] [What about the content of this article? (0)] [Affiliation(s)] [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] [What about the content of this article? (0)] [Affiliation(s)] [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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