Analysis of the presence of the GJB6 mutations in patients heterozygous for GJB2 mutation in Brazil.

Mutations in the GJB2 gene, mainly 35delG, are responsible for most autosomal recessive inherited genetic hearing loss. The audiometric standard of these hearing losses remains inconsistent and other genes, such as GJB6, have been involved in association with GJB2. The objective of the study was to identify the deletions del(GJB6-D13S1830) and del(GJB6-D13S1854) in patients heterozygous for 35delG/GJB2 and analyze the phenotype they present. 101 patients with mild to profound degree of sensorineural hypoacusis were evaluated. The allele-specific PCR technique was used to identify 35delG. The del(GJB6-D13S1830) and del(GJB6-D13S1854) were identified through the PCR multiplex technique. 90% of the subjects presented a normal genotype for the analyzed mutations; 6.93% were shown to be heterozygous for 35delG/GJB2 and 1% presented compound heterozygosis GJB2/GJB6). The data found reinforced the hypothesis of an interaction of more than one gene as the cause of autosomal recessive genetic hearing loss and emphasized the importance of an early diagnosis for appropriate intervention.