Age-related hearing loss is a common condition among older individuals that contributes to substantially reduced quality of life31. In the United States, approximately 33% of the population between ages of 65 and 74 are subject to hearing loss, and after 75 years of age about 50% of the population have hearing problems (data from the National Institute on Deafness and Other Communication Disorders available at https://www.nidcd.nih.gov/health/age-related-hearing-loss). There are many known causes of age-related hearing loss, including age-induced changes to the structure of the inner and middle ear, and also complex changes along the nerve pathways from the ear to the brain32. Epidemiological studies, such as The Epidemiology of Hearing Loss Study17 and National Health and Nutrition Examination Survey 1999–200418, have shown that the major risk factors for age-related hearing loss are noise exposure and smoking. While the mechanism for noise-associated hearing loss is reasonably well understood, this is not the case for nicotine exposure. Our current PheWAS for CYP2A6 alleles identified association with hearing loss symptoms in nicotine-exposed elderly subjects. This result supports a harmful effect of smoking on auditory
