Multilevel analysis of patients with hypophosphatasemia: genomic, epigenomic and isoenzyme activity profiles
8 affiliations
- 1Hospital Universitario Marques de Valdecilla
- 2Instituto de Investigacion Marques de Valdecilla
- 3Universidad of Cantabria; Faculty of Medicine
- 4Hospital General Universitario Sierrallana.
- 5Centro de Investigación Biomédica en Red de Enfermedades Raras
- 6Reference Laboratory of Catalonia, NGS
- 7Universidade de Santiago de Compostela Centro Singular de Investigacion en Medicina Molecular e Enfermidades Cronicas
- 8Fundación Pública Galega Medicina Xenómica
Abstract
Background: Hypophosphatasemia is the biochemical hallmark of (HPP), a rare genetic condition caused by deficient activity of tissue-nonspecific alkaline phosphatase (ALP) due to pathogenic variants in the ALPL gene. However, a substantial number of patients with persistently low serum levels of ALP (hypophosphatasemia) lack identifiable mutations, complicating diagnosis and management.
Aim: To investigate the molecular basis of low ALP activity in adult patients without detectable ALPL mutations using an integrative multi-omics approach and isoenzyme profiling.
Methods: We studied 50 adult patients with low serum ALP and 20 healthy controls. Genetic analysis included targeted sequencing of ALPL exons and promoter, and whole-exome sequencing in mutation-negative cases. Promoter methylation was explored by MassARRAY, and ALPL mRNA expression was determined by RT-qPCR. Total and bone-specific ALP, and bone turnover markers were determined. Isoenzyme fractions were analyzed by agarose gel electrophoresis.
Results: Pathogenic ALPL variants were identified in 24 patients, whereas the remaining 26 were non-carriers. Non-carriers did not have identifiable variants in the ALPL promoter or in other genes related to bone and mineral homeostasis. Likewise, ALPL expression levels, and promoter methylation were similar in all groups. PINP and β-CTX levels were similarly reduced in carriers and non-carriers, in comparison with controls. In contrast, mutation carriers exhibited a marked reduction in the hepatic ALP isoenzyme, while mutation-negative individuals showed relatively preserved liver ALP activity. Moreover, in non-carriers, we did not find the expected correlation between total and bone-specific ALP in serum.
Conclusions: Taken together, these findings, along the normal serum levels of pyridoxal-phosphate, suggest that in patients with persistent hypophosphatasemia without ALPL mutations, low serum ALP levels may reflect an enzymatic defect affecting bone more than liver. Longitudinal follow-up of these patients will be essential to determine whether low ALP levels are associated with long-term musculoskeletal consequences.
Related
- Physical activity and atherosclerosis index: a multilevel analysis based on CHARLS 2011–2013
- Environmental and psychosocial contexts of device-measured physical activity and sedentary behaviour in semi-urban Nepal: a multilevel analysis
- Gamete Cryopreservation: Molecular Mechanisms of Cellular Injury and Epigenomic Alterations in Human and Animal Models
- The Urban Exposome: Genomic, Epigenomic, and Evolutionary Consequences Across Species
- Efficacy of Tuina on pain, functional activity, muscle strength and brain activity for patients with knee osteoarthritis in Shanghai: a randomised controlled trial protocol
BibTeX
@article{real2026multilevel,
title = {{Multilevel analysis of patients with hypophosphatasemia: genomic, epigenomic and isoenzyme activity profiles}},
author = {Álvaro Del Real and Sofía Álvarez Villalobos and María Ortiz Espejo and Carolina Sañudo and Ana I. Vega and Leyre Riancho-Zarrabeitia and Teresa Amigo and Maria Teresa García-Unzueta and Nuria Puente Ruiz and Alex Garcia Tellado and Olga Gutiérrez Saiz and Javier Lopez Montiel and Juan Ansede-Bermejo and Jose Luis Fernández-Luna and Domingo González-Lamuño and Angel Carracedo and Jose A. Riancho},
journal = {Frontiers in Endocrinology},
year = {2026},
month = oct,
doi = {10.3389/fendo.2026.1910750},
url = {https://www.frontiersin.org/articles/10.3389/fendo.2026.1910750/full},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Multilevel analysis of patients with hypophosphatasemia: genomic, epigenomic and isoenzyme activity profiles
AU - Álvaro Del Real
AU - Sofía Álvarez Villalobos
AU - María Ortiz Espejo
AU - Carolina Sañudo
AU - Ana I. Vega
AU - Leyre Riancho-Zarrabeitia
AU - Teresa Amigo
AU - Maria Teresa García-Unzueta
AU - Nuria Puente Ruiz
AU - Alex Garcia Tellado
AU - Olga Gutiérrez Saiz
AU - Javier Lopez Montiel
AU - Juan Ansede-Bermejo
AU - Jose Luis Fernández-Luna
AU - Domingo González-Lamuño
AU - Angel Carracedo
AU - Jose A. Riancho
PY - 2026
DA - 2026/10/30
JO - Frontiers in Endocrinology
DO - 10.3389/fendo.2026.1910750
UR - https://www.frontiersin.org/articles/10.3389/fendo.2026.1910750/full
AB - Background: Hypophosphatasemia is the biochemical hallmark of (HPP), a rare genetic condition caused by deficient activity of tissue-nonspecific alkaline phosphatase (ALP) due to pathogenic variants in the ALPL gene. However, a substantial number of patients with persistently low serum levels of ALP (hypophosphatasemia) lack identifiable mutations, complicating diagnosis and management. Aim: To investigate the molecular basis of low ALP activity in adult patients without detectable ALPL mutations using an integrative multi-omics approach and isoenzyme profiling. Methods: We studied 50 adult patients with low serum ALP and 20 healthy controls. Genetic analysis included targeted sequencing of ALPL exons and promoter, and whole-exome sequencing in mutation-negative cases. Promoter methylation was explored by MassARRAY, and ALPL mRNA expression was determined by RT-qPCR. Total and bone-specific ALP, and bone turnover markers were determined. Isoenzyme fractions were analyzed by agarose gel electrophoresis. Results: Pathogenic ALPL variants were identified in 24 patients, whereas the remaining 26 were non-carriers. Non-carriers did not have identifiable variants in the ALPL promoter or in other genes related to bone and mineral homeostasis. Likewise, ALPL expression levels, and promoter methylation were similar in all groups. PINP and β-CTX levels were similarly reduced in carriers and non-carriers, in comparison with controls. In contrast, mutation carriers exhibited a marked reduction in the hepatic ALP isoenzyme, while mutation-negative individuals showed relatively preserved liver ALP activity. Moreover, in non-carriers, we did not find the expected correlation between total and bone-specific ALP in serum. Conclusions: Taken together, these findings, along the normal serum levels of pyridoxal-phosphate, suggest that in patients with persistent hypophosphatasemia without ALPL mutations, low serum ALP levels may reflect an enzymatic defect affecting bone more than liver. Longitudinal follow-up of these patients will be essential to determine whether low ALP levels are associated with long-term musculoskeletal consequences.
SN - 1664-2392
ER -