engleski

Detection of the 35delG mutation in the connexin 26 (GJB2) gene in Croatian patients with nonsyndromic hearing impairment

Hearing loss is one of the most common congenital disorders affecting 1 to 3 of 1000 newborns. NSHI (nonsyndromic hearing impairment) is observed in about 70% of cases with a genetic background and is mostly caused by autosomal recessive mutations. Mutations in GJB2 gene, encoding gap junction beta 2 protein (connexin 26) are found in 50% Caucasians with profound NSHI. 35delG is the most frequent GJB2 mutation leading to NSHI in European populations, especially of Mediterranean descent, with carrier frequency up to 1/30. The aim of this study was to determine the allelic frequency of 35delG mutation in patients with NSHI and in normal hearing individuals in the Croatian population. The method we used is based on the principle of PCR-mediated site-directed mutagenesis, followed by a BsiYI digestion. PCR products were subsequently size-separated by electrophoresis on a 4% agarose gel and analyzed. Results: we analyzed 29 unrelated individuals with nonsyndromic sensory deafness and 342 normal hearing individuals. Among the patients with NSHI the 35delG mutation was found on 48.27% alleles. The carrier frequency among the healthy control individuals was 5 in 342 (1.46%). Conclusion: The relatively high prevalence of 35delG mutation in GJB2 gene among Croatian patients with NSHI shows that this mutation is one of the leading causes of NSHI in Croatia. Hence, early screening for 35delG mutation would greatly improve the genetic counselling, prevention and treatment strategies in our patients with NSHI.

35delG mutation; Connexin 26; deafness; molecular analysis

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