Association between polymorphisms in SOD1 and noise-induced hearing loss in Chinese workers.

CONCLUSION: SOD1 is an important gene related to noise-induced hearing loss (NIHL), and its effect is dependent on noise exposure levels.

OBJECTIVES: To test whether the polymorphisms in the CuZn-superoxide dismutase gene (SOD1) are associated with susceptibility to NIHL in the Chinese population.

METHODS: Audiometric data from 2400 Chinese Han people exposed to occupational noise were analyzed. DNA samples were collected from the 10% most susceptible and the 10% most resistant individuals. Four SNPs in the introns of SOD1 were genotyped and their effects and interactions with noise exposure were analyzed.

RESULTS: Genotype AA of rs2070424 conferred protection against NIHL (adjusted OR = 0.45, p = 0.005), while GG of rs10432782 was a risk genotype (adjusted OR = 1.88, p = 0.026). One protective haplotype TATG (OR = 0.56, p = 0.003) and two risk haplotypes, CATG and TGGA (OR = 1.58, 28.75 and p = 0.017, <0.001, respectively) were identified. Significant interactions between SOD1 SNPs and noise levels were found. Further analysis of effects of SOD1 SNPs found that those carrying GG genotype of rs10432782 had significantly higher SOD1 activity (p = 0.022), but a significantly lower level of malondialdehyde in plasma, compared with TT carriers (p = 0.007).