Odonto-hypophosphatasia with Tooth Agenesis: a Case Report.

Odonto-hypophosphatasia (odonto-HPP) is a mild form of hypophosphatasia (HPP) characterised by premature exfoliation of primary and/or permanent teeth accompanied by low serum alkaline phosphatase (ALP) activity levels, without abnormalities of the skeletal system. Tooth agenesis (TA) is a common developmental anomaly characterised by the absence of one or more teeth due to the failure of tooth formation. In this study, the present authors report on a family simultaneously affected by odonto-HPP and TA for the first time. Comprehensive genetic analysis identified two novel missense variants (c.103G>A and c.247G>A) in the ALPL gene associated with odonto-HPP and no pathogenic variants in the reported TA genes, which may expand the genetic spectrum of odonto-HPP and imply an unforeseen additional dental abnormality associated with HPP.