Single nucleotide polymorphisms in the cadherin 23 (CDH23) gene in Polish workers exposed to industrial noise

Abstract

Single nucleotide polymorphisms (SNPs) are the most frequent type of variation in the human genome and may underlie differential susceptibility to common genetic diseases. A candidate gene for susceptibility to noise-induced hearing loss (NIHL) is Cadherin 23 (CDH23). This study aimed to analyze genetic variation in the CDH23 gene in a group of 10 individuals derived from a cohort of 949 workers exposed to noise, and consisted of five persons from each of the resistant and susceptible extremes. DNA samples were collected and the coding exons of CDH23 were sequenced. We identified a total of 35 SNPs: 11 amino acid substitutions, 8 silent nucleotide changes, and 16 substitutions in intervening sequences. Ten of the 11 amino acid substitutions were previously shown also to segregate in a Cuban population. The nonsynonymous SNPs localized to the part of the gene encoding the extracellular domain of Cadherin 23, in particular ectodomains 5, 13, 14, 15, 16, 17, 19, and 22. One amino acid change occurred at a conserved position in ectodomain 5. Our results provide a framework for future study of polymorphisms in CDH23 as risk factor for NIHL.