Connexin-26-associated deafness: Phenotypic variability and progression of hearing loss

Purpose: To evaluate genotype-phenotype correlation over time for a cohort of children with connexin-26 (GJB2)-associated autosomal recessive hearing loss. Methods: Fifty-two children were identified from a database of individuals with homozygous or compound heterozygous mutations in GJB2 and subjected to chart review of their otolaryngologic and serial audiometric evaluations. Genotype-phenotype correlations were identified among the members of this group by appropriate statistical analyses. Results: Hearing loss was most severe in individuals with two truncating mutations in GJB2 and mildest in those with two nontruncating mutations. Progressive hearing loss was seen directly by serial audiometry in 24% of all subjects, and suggested in a total of 28% when those with normal newborn hearing screens and subsequent hearing loss were included. Progression was particularly common among carriers of the p. V37I allele either in homozygosity or in compound heterozygosity with a truncating allele; these children are primarily of Asian descent and demonstrate mild, slowly progressive hearing loss. Conclusions: Phenotype in GJB2-associated hearing loss is correlated with genotype, with truncating mutations giving rise to more severe hearing loss. Progression of hearing loss is not uncommon, especially in association with the p. V37I allele. These results suggest that close audiometric follow-up is warranted for patients with GJB2-associated recessive hearing loss. Genet Med 2010:12(3):174-181.