Stapes ankylosis in a family with a novel NOG mutation: otologic features of the facioaudiosymphalangism syndrome.

OBJECTIVE: To report the phenotype-genotype correlation in a Belgian family that was ascertained to have a novel missense mutation in the NOG gene mapping to chromosome 17q22. STUDY DESIGN: To describe the phenotype, a retrospective case study was performed based on the otologic, audiologic, ophthalmologic, and radiologic data of the mutation carriers of the NOG gene. SETTING: Tertiary referral center. PATIENTS: All members of a Belgian kindred who carried the novel missense mutation in the NOG gene (NOG, Trp205Cys [W205C]; 1426G>C). INTERVENTIONS: Diagnostic otologic and ophthalmologic examination, audiometric analysis, and radiologic imaging. MAIN OUTCOME MEASURES: Phenotype-genotype correlations. RESULTS: All five mutation carriers had a typical facies. Bilateral proximal symphalangism and hyperopia were present in 80%. Five of 10 ears also had progressive early-onset conductive hearing loss caused by stapes ankylosis. CONCLUSIONS: So far, 14 independent NOG mutations have been identified. The autosomal dominant disorder described in the present family was caused by a novel NOG missense mutation (NOG, Trp205Cys [W205C]; 1426G>C). The phenotype correlated well with the facioaudiosymphalangism syndrome. The mutation carriers demonstrated progressive multiple joint fusions, hyperopia, early-onset conductive deafness, and a typical facies.     

The facio-audio-symphalangism syndrome in a four generation family with a nonsense mutation in the NOG-gene

We report a four generation family with features of the facio-audio-symphalangism syndrome. This condition is characterized by proximal symphalangism, conductive hearing loss due to stapes fixation and a distinctive facies. A novel nonsense mutation in the NOG gene on chromosome 17q22 was identified in the patients. The variable expression and progressive nature of the syndrome is well illustrated by this family. The role of Noggin as the causative factor of symphalangism is discussed.