Hypophosphatasia (HPP) is a rare skeletal dysplasia caused by variants in the () gene. More than 400 pathogenic variants of the gene have been registered in the ALPL gene variant database. Here, we describe the case of a Japanese child with odonto-hypophsphatasia (odonto-HPP) and a novel variant.
At the age of 2 years and 1 month, he prematurely lost one deciduous tooth, with the root intact, when he fell and hit his face lightly. Three months later, he lost another adjacent deciduous tooth without incentive. His serum alkaline phosphatase (ALP) level was 72 U/L. His urine phosphoethanolamine (PEA) level was extremely high at 938 μmol/mg·Cre. The serum pyridoxal 5′-phosphaye (PLP) level was 255.9 nmol/L. Based on the clinical symptoms and laboratory findings, the patient was clinically diagnosed with odonto-HPP. Genetic analysis of the gene revealed a heterozygous variant (NM_000478.6:c.1151C>A, p.Thr384Lys).
We report a case of odonto-HPP with a novel variant in the gene. HPP is a rare disease, and the heterozygous mutation in the gene highlights the novelty of this case.

© 2024 Walter de Gruyter GmbH, Berlin/Boston.