engleski

Recessive mutations at the DFNB1 locus in patients with non-syndromic hearing loss from Croatia

Recessive mutations at the DFNB1 locus (13q11-12) are the cause of about 50% congenital, nonsyndromic hearing loss (NSHL). The genes GJB2 (connexin 26) and GJB6 (connexin 30) are mapped at the DFNB1 locus. Among mutations in GJB2 gene, 35delG mutation accounts for approximately 70% of all GJB2 mutant alleles in most European population. The aim of the present study was to determine 1. The frequency and type of mutations in the coding region of GJB2 gene, 2. The frequency of splice-site mutation IVS1+1G>A in noncoding region of GJB2 gene, and 3. The frequency of del(GJB6-D13S1830) in GJB6 gene in 58 unrelated patients with NSHL from Croatia. The coding region of the GJB2 gene was sequenced and the GJB6 deletion was analyzed by two specific PCR reactions. We tested mutation IVS1+1G>A in GJB2 gene by MLPA analysis. About half of our patients presented with one or two mutations in GJB2 gene. Beside previously reported recessive mutations associated with NSHL, we identified one novel variant -24A>C in 5\'UTR. The frequency of 35delG allele was 35.3% (41/116). Allelic frequencies of other common mutations in our subjects accounted for 2.6%-0.9% of analyzed chromosomes. The GJB6 deletion was not found in tested subjects. The 35delG was the most frequent identified mutation, hence it has important role as a cause of NSHL in Croatian population. High mutation rate indicates that testing of GJB2 gene will clarify the genetic cause in considerable number of the cases of recessive NSHL in Croatia.

Hearing loss

nije evidentirano