KIEDY NALEŻY WYKONAĆ TEST NA OBECNOŚĆ MUTACJI IVS1+1G>A GENU GJB2 U PACJENTÓW Z IZOLOWANYM NIEDOSŁUCHEM ZMYSŁOWO-NERWOWYM?

Abstract

BackgroundThe splice site nucleotide substitution IVS1+1G>A in the non-coding part of the GJB2 gene is one of the recessive pathogenic mutations causing nonsyndromic sensorineural hearing loss (NSHL). We present here the results of a study of IVS1+1G>A among Belarusian patients with NSHL as well as among Belarusian controls with normal hearing.Material and MethodsThe PCR-RFLP method was used for genotyping. All tested patients were subdivided into three groups: those who carried only one mutant allele of GJB2 exon 2 (group A, 28 patients), those with no mutation of GJB2 exon 2 (group B, 150 patients), and patients with two mutations previously detected in the second exon of GJB2 or with one mutation and a large GJB6 deletion ∆D13S1830 (group C, 223 patients). Also 300 Belarusian people with normal hearing were screened for IVS1+1G>A.ResultsWe detected 7 patients with IVS1+1G>A mutation in the A group, which explained hearing loss in 25% of this deafness cohort. None of the B or C group patients carried the IVS1+1G>A mutation. We also did not find any IVS1+1G>A mutation carriers among the 300 Belarusian control people with normal hearing.ConclusionsIVS1+1G>A is the third-most frequent mutation (after 35delG and 312del14) among Belarusian patients with NSHL; its rate is 1.8% for the patient cohort we studied and the population frequency is below 0.33%. We propose to include the IVS1+1G>A mutation into a laboratory screening protocol for those patients with NSHL that carry one mutant allele of GJB2 exon 2.