Polymorphisms in Genes Involved in Oxidative Stress Response in Patients with Sudden Sensorineural Hearing Loss and Meniere's Disease in a Japanese Population

The etiologies of idiopathic sudden sensorineural hearing loss (SSNHL) and Meniere's disease remain unclear. Recently, accumulating evidence has demonstrated that oxidative stress is related to the pathology of inner ear disease. Because genetic factors may contribute partly to the etiologies of SSNHL and Meniere's disease, we investigated the associations between genetic polymorphisms located in oxidative stress response genes and susceptibility to SSNHL and Meniere's disease. We compared 84 patients affected by SSNHL, 82 patients affected by Meniere's disease, and 2107 adults (1056 men and 1051 women; mean age, 59.2 years; range, 40-79 years) who participated in the National Institute for Longevity Sciences, Longitudinal Study of Aging. Multiple logistic regression was used to calculate odds ratios for SSNHL and Meniere's disease in individuals with polymorphisms in the genes glutathione peroxidase 1 (GPX1) (Pro198Leu, rs1050450), paraoxonase 1 (PON1) (Gln192Arg, rs662; and Met55Leu, rs854560), PON2 (Ser311Cys, rs7493), and superoxide dismutase 2 (SOD2) (Val16Ala, rs4880), with adjustment for age and gender. No significant differences in the distribution of the genotypes at these polymorphisms were observed among individuals with SSNHL and Meniere's disease and controls. No significant risk for SSNHL and Meniere's disease was observed in the additive genetic model, regardless of moderating variables. The C allele of SOD2 (rs4880) was more frequent in Meniere's disease cases with a hearing level over 50 dB compared with cases with a hearing level below 50 dB, suggesting that this polymorphism is associated with progression of a hearing loss in Meniere's disease. In conclusion, no significant associations between the polymorphisms of GPX1, PON1, PON2, and SOD2 and risk of SSNHL and Meniere's disease were observed in this Japanese case-control study.