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Hypophosphatasia screening in pediatric age based on records

Endocrinology & Metabolism International Journal
Ignacio Díez-Lopez,1 Luis Aldamiz-Echevarría,2 Fernando Andrade,1 Pablo Suarez,1 Domingo González-Lamuño,3 María Unceta,1 Arantza Arza,1 María del Mar Rovira,4 Olatz Villate1

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Introduction: hypophosphatasia (HPP) is a congenital disease, characterized by a defect in bone and dentary mineralization, secondary to a deficiency in the biosynthesis of non-specific tissue isoenzyme of alkaline phosphatase (TNSALP), resulting in decreased levels of alkaline phosphatase (ALP) activity and the extracellular accumulation of its substrates. Our goal was to establish the interest of screening the hospital databases of pediatric patients with low levels of ALP for the diagnosis of HPP.
Materials and methods: during the period from September 2016 to September 2017, 23231 patients were tested for ALP, 1752 of them showed low levels of ALP. Based on the clinic, basal disease and that in previous analyses they did not present ALT norm values, 14 cases were selected: 8 cases associated with scoliosis, 1 case associated with early puberty, 1 case of low size, 1 case of liver disease and myasthenia and 1 case of teething problems. ALPL gene was studied in those cases.
Results: the latter case was of an 8-year-old male with a pathological variant of HPP: c.343_348dupACCGCC (p.Thr115_Ala116dup) in exon 5 in dominant heterozygous, inherited from his mother. At the substrate level the levels of pyridoxal-5-phosphate were above 50μg/L.
Conclusion: the diagnostic strategy with a high index of clinical suspicion of HPP should include the observation of low levels of serum ALP activity. Our study shows that HPP is an underdiagnosed disease.
An appropriate protocol to detect HPP in a clinical setting in tertiary care hospitals is required.


Hypophosphatasia, Population screening, Pediatrics, Alkaline phosphatase, Inorganic pyrophosphate