Phenotype of the first otosclerosis family linked to OTSC10.

OBJECTIVES

To report on the audiometric findings in the first otosclerosis family linked to OTSC10.

STUDY DESIGN

Retrospective cohort study.

METHODS

A family study in a large otosclerosis family was performed, and a pedigree was constructed. Examination of all family members consisted of medical history guided by a questionnaire, pure-tone audiometry, otoscopy, and collection of blood samples for genetic linkage analysis. In addition, a selected group underwent stapedial reflex measurements and tympanometry. Cross-sectional as well as longitudinal analyses of audiometric data were performed.

RESULTS

Eleven family members were identified as clinically affected and were all carriers of the disease haplotype. Twelve clinically unaffected family members carried the disease haplotype as well. Cross-sectional analyses of clinically affected family members showed no significant progression of air conduction (AC) thresholds, bone conduction (BC) thresholds, and air-bone gap (ABG) levels with increasing age. Longitudinal regression analyses in one family member revealed significant deterioration of AC thresholds at all frequencies. The BC thresholds showed a significant increase with advancing age at 0.5 kHz, 2 kHz, and 4 kHz. A significant progression of ABG was seen at 8 kHz.

CONCLUSIONS

The intersubject variation, in terms of age of onset, level of progression, and audiogram configuration, was remarkable, probably due to reduced penetrance and variable expression of the disease. Long-term audiometric data in one patient, however, were useful to demonstrate progression of hearing impairment.