Mini Review Article

Hypophosphatasia in adults

Antonia A. Kountouri¹, Anna Papadopoulou²

1. Biochemical Laboratory, General Hospital of Nikaia-Piraeus "Agios Panteleimon" - General Hospital of West Attica "Agia Varvara", Athens, Greece
2. 3^rd Department of Pediatrics, University General Hospital "Attikon", University of Athens, Medical School, Athens, Greece

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Keywords: ALPL gene, PEA, PLP, Alkaline phosphatase, Asfotase alfa

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Abstract

Hypophosphatasia (HPP) is a sporadic inheritable disease. Patients suffer from defective bone and teeth mineralization, due to low levels of alkaline phosphatase (ALP). It is caused by mutations in the ALPL gene which encodes the tissue-nonspecific isoenzyme (TNAP or TRANSALP) of alkaline phosphatase. Hypophosphatasia is classified into six forms: lethal perinatal, benign prenatal, infantile, childhood, adult and odontohypophosphatasia. The adult form is the rarest and the mildest of all types characterized by low levels of alkaline phosphatase, increased levels of pyridoxal-5'-phosphate (PLP) in serum and increased levels of phosphoethanolamine (PEA) in urine. ALPL mutations associated with adult hypophosphatasia are either autosomal recessive or autosomal dominant. Patients' phenotype depends on the site of the enzyme these mutations affect. Although, there is not a treatment for this disease actually, enzyme replacement treatment (ERT) with asfotase alfa promises a lot to patients.

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