The phenotype of the first otosclerosis family linked to OTSC5

Abstract

Objective: To report the audiometric and radiologic findings in the first otosclerosis family linked to OTSC5.

Study design: A clinical investigation of a family linked to OTSC5, including analyses of audiometric data and of high-resolution computed tomography (CT) images of the temporal bones from genetically affected family members.

Setting: Tertiary referral center.

Patients: Family members from a four-generation pedigree with otosclerosis segregating as an autosomal dominant trait.

Main outcome measure(s): Pre-surgery pure tone audiometric data. Classification of otosclerotic foci on high-resolution spiral CT images of the temporal bones of genetically affected individuals.

Results: Audiometric data showed a considerable degree of phenotypic variability. Cross-sectional regression analysis did not disclose any clear age dependence of threshold-related data. Systematic differences between mean parameter values relating to the thresholds in the best or the worst ear were found. High-resolution CT images revealed a fenestral otosclerotic focus in seven of nine (78%) clinically affected individuals and cochlear foci in one of these seven patients.

Conclusion: The phenotype of OTSC5 seems to be variable. Additional long-term audiometric data are needed to construct age-related typical audiograms, which may also facilitate the comparison between phenotypes of the different otosclerosis loci. The detection rate of otospongiotic foci in our study group is similar or lower compared with previous reports on CT data in consecutive otosclerosis patients who had stapes replacing surgery.