A mutation in FRIZZLED2 impairs Wnt signaling and causes autosomal dominant omodysplasia

Autosomal dominant omodysplasia is a rare skeletal dysplasia characterized by short humeri, radial head dislocation, short first metacarpals, facial dysmorphism and genitourinary anomalies. We performed next-generation whole-exome sequencing and comparative analysis of a proband with omodysplasia, her unaffected parents and her affected daughter. We identified a de novo mutation in FRIZZLED2 (FZD2) in the proband and her daughter that was not found in unaffected family members. The FZD2 mutation (c.1644G > A) changes a tryptophan residue at amino acid 548 to a premature stop (p.Trp548*). This altered protein is still produced in vitro, but we show reduced ability of this mutant form of FZD2 to interact with its downstream target DISHEVELLED. Furthermore, expressing the mutant form of FZD2 in vitro is not able to facilitate the cellular response to canonical Wnt signaling like wild-type FZD2. We therefore conclude that the FRIZZLED2 mutation is a de novo, novel cause for autosomal dominant omodysplasia.