Nicole J. D. Weegerink

In the present study, genotype–phenotype correlations in eight Dutch DFNB8/10 families with compound heterozygous mutations in TMPRSS3 were addressed. We compared the phenotypes of the families by focusing on the mutation data. The compound heterozygous variants in the TMPRSS3 gene in the present families included one novel variant, p.Val199Met, and four previously described pathogenic variants, p.Ala306Thr, p.Thr70fs, p.Ala138Glu, and p.Cys107Xfs. In addition, the p.Ala426Thr variant, which had previously been reported as a possible polymorphism, was found in one family. All affected family members reported progressive bilateral hearing impairment, with variable onset ages and progression rates. In general, the hearing impairment affected the high frequencies first, and sooner or later, depending on the mutation, the low frequencies started to deteriorate, which eventually resulted in a flat audiogram configuration. The ski-slope audiogram configuration is suggestive for the involvement of TMPRSS3. Our data suggest that not only the protein truncating mutation p.T70fs has a severe effect but also the amino acid substitutions p.Ala306Thr and p.Val199Met. A combination of two of these three mutations causes prelingual profound hearing impairment. However, in combination with the p.Ala426Thr or p.Ala138Glu mutations, a milder phenotype with postlingual onset of the hearing impairment is seen. Therefore, the latter mutations are likely to be less detrimental for protein function. Further studies are needed to distinguish possible phenotypic differences between different TMPRSS3 mutations. Evaluation of performance of patients with a cochlear implant indicated that this is a good treatment option for patients with TMPRSS3 mutations as satisfactory speech reception was reached after implantation.

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. Laryngoscope, 2011