A novel mutation in the vWFA2 domain of the COCH gene in an Italian DFNA9 family

Abstract Objective: Hearing loss (HL) is the most common form of sensory impairment, affecting millions of individuals worldwide. Pre-lingual non-syndromic hearing loss is present in 1 in 700 children and in half of the cases the hearing impairment is caused by genetic factors. Methods: We analysed an Italian family with a bilateral sensorineural HL present in several family members and inherited in an autosomal dominant manner. To perform a linkage study, subjects were genotyped with high density SNP arrays. Parametric linkage analysis using Merlin detected a significant 40-Mb locus on chromosome 14. Since the COCH gene, already known to be involved in causing HL, was located within this interval, a mutational search was carried out. Result: A novel mutation (p.A487P) affecting a highly conserved residue located within the vWFA2 domain was detected and segregates with the disease. Conclusion: This is the first Italian case of HL due to mutations within the COCH gene and it is also the first one showing some individuals affected by vestibular dysfunction due to the direct involvement of the vWFA2 domain.