SOD2 V16A SNP in the Mitochondrial Targeting Sequence is Associated with Noise Induced Hearing Loss in Chinese Workers

OBJECTIVE To investigate whether single nucleotide polymorphisms (SNPs) in the Mn-superoxide dismutase gene (SOD2) underlie the susceptibility to noise-induced hearing loss (NIHL). METHODS Audiometric data from 2400 Chinese Han workers who exposed to occupational noise were analyzed. DNA samples were collected from the 10% most susceptible and the 10% most resistant individuals, and five SNPs (SOD2 rs2842980, rs5746136, rs2758331, rs4880 and rs5746092) were genotyped by Taqman SNP Genotyping Kits. The SNP main effects and interactions between noise exposure and SNP were analyzed using logistic regression. Haplotypes were analyzed by using Haploview software. RESULTS The CT genotype of rs4880 (SOD2 V16A SNP) was associated with a higher risk of NIHL (covariates-adjusted OR, 2.18; 95% CI, 1.34-3.54, P=0.002). Haplotype analysis revealed that the frequency of AGCCG at the five SNP loci was significantly higher in the susceptible group (P=0.020). With AGCTG as the reference, the OR (95% CI) was 2.63 (1.14, 6.06). The rs4880 polymorphisms imposed larger effects when the carriers were exposed to higher levels of noise, indicating the interaction between SNP and noise exposure. CONCLUSIONS Our results suggest that SOD2 V16A SNP in the mitochondrial targeting sequence is associated with noise induced hearing loss in Chinese workers, and this effect was enhanced by higher levels of noise exposure.