CONCLUSION: This study illustrates that UCP2 Ala55Val polymorphisms exhibit a significant association with age-related hearing loss in the Japanese population. OBJECTIVES: Mitochondrial uncoupling proteins (UCPs) have been suggested to play a protective role against neuron oxidative damage and a thermal signaling role in neuron modulation in the inner ear. In the current study, we examined the relationship between gene polymorphisms in UCP1 and UCP2 and hearing impairment (HI) in Japanese elderly. METHODS: A total of 1547 subjects aged 40-79 years and living in Aichi prefecture, Japan, were entered into this study. Subjects were followed up every 2 years, and the cumulative number of subjects for 3 sequential examinations in 6 years was 4942 persons. Detailed questionnaires, pure-tone audiometry measurements, and UCP1 A-3826G and UCP2 Ala55Val polymorphisms were examined. Using generalized estimating equations, associations between HI and gene polymorphisms in UCP1 and UCP2 with age, sex, history of occupational noise exposure, and body mass index were analyzed under dominant, recessive, and additive models. RESULTS: UCP1 A-3826G polymorphism did not exhibit any significant association with HI. However, UCP2 Ala55Val polymorphism did exhibit a significant association with HI under all the dominant (p = 0.0167), recessive (p = 0.0411), and additive (p = 0.0061) models.
CONCLUSION: This study illustrates that UCP2 Ala55Val polymorphisms exhibit a significant association with age-related hearing loss in the Japanese population. OBJECTIVES: Mitochondrial uncoupling proteins (UCPs) have been suggested to play a protective role against neuron oxidative damage and a thermal signaling role in neuron modulation in the inner ear. In the current study, we examined the relationship between gene polymorphisms in UCP1 and UCP2 and hearing impairment (HI) in Japanese elderly. METHODS: A total of 1547 subjects aged 40-79 years and living in Aichi prefecture, Japan, were entered into this study. Subjects were followed up every 2 years, and the cumulative number of subjects for 3 sequential examinations in 6 years was 4942 persons. Detailed questionnaires, pure-tone audiometry measurements, and UCP1A-3826G and UCP2 Ala55Val polymorphisms were examined. Using generalized estimating equations, associations between HI and gene polymorphisms in UCP1 and UCP2 with age, sex, history of occupational noise exposure, and body mass index were analyzed under dominant, recessive, and additive models. RESULTS:UCP1A-3826G polymorphism did not exhibit any significant association with HI. However, UCP2 Ala55Val polymorphism did exhibit a significant association with HI under all the dominant (p = 0.0167), recessive (p = 0.0411), and additive (p = 0.0061) models.