Hypophosphatasia: Novel Mutation Associated With An Atypical Newborn Presentation

<p>Hypophosphatasia, a rare genetic disease affecting bone metabolism, is characterized by decreased activity of tissue nonspecificalkaline phosphatase (TNAP). The gene encoding TNSP (ALPL) has considerable allelic heterogeneity, which couldexplain different degrees of enzyme activity determining a wide clinical variability. We report the case of a preterm newbornin whom a corneal opacity was detected at birth. Blood tests performed to investigate this finding showed low alkalinephosphatase concentrations. The corneal opacity disappeared within a week but alkaline phosphatase remained persistentlylow. With persistently decreased levels of alkaline phosphatase, upon suspicion of hypophosphatasia, plain radiographydetected changes suggestive of rickets. Sequencing of the ALPL gene revealed a heterozygous variant that has not beendescribed in the literature to date.</p><p>Our patient’s condition could be an atypical neonatal form of the syndrome, with a mild phenotype, very different from theclassic neonatal form which can lead to severe skeletal disease and respiratory failure. However, it could also be an earlydiagnosis of the childhood form, with better prognosis.</p>