Genetic associations in age-related hearing thresholds

Objective: To determine the inheritance of age-related hearing loss. Design: Cohort study comparing aggregation of hearing levels in genetically unrelated people (spouse pairs) and in genetically related people (sibling pairs, parent-child pairs). Setting: Framingham Heart Study biennial Examination 15 (1973-1975) and Framingham Offspring Study Examination 6 (1995-1998). Subjects: Members of the Framingham cohorts with hearing tests and with a relative in the Framingham hearing study. Main Outcome Measures: Audiometric pure-tone thresholds at 250 to 8000 Hz were obtained and pure-tone average (PTA) hearing thresholds were calculated for the middle (0.5-2 kHz), high (4-8 kHz), and low (0.25-1 kHz) frequencies for each ear. The shape of the audiogram was categorized as either normal, abrupt high-frequency loss (sensory phenotype) or flat loss (strial phenotype). Correlations were made using the Familial Correlations program of the Statistical Analysis for Genetic Epidemiology software system. The level of significance was P=.01. Results: Hearing threshold levels did not aggregate in spouses. Significant aggregation was noted in siblings and parent-child pairings for PTA at low, middle, and high frequencies. Sisters but not brothers had significant aggregation of each PTA measure. Mother-daughter and mother-son pairs but not father-son pairs had significant aggregation of hearing levels. For the sensory phenotype, there was significant aggregation in all related pairs except for father-child pairs. For the strial phenotype, there was significant aggregation of hearing levels in the related female pairs but not in the related male pairs. Conclusions: A clear familial aggregation occurs for age-related hearing levels, sensory presbycusis phenotypes, and strial presbycusis phenotypes. The aggregations are stronger in women than in men. The heritability estimate was greater for the strial phenotypes than for the sensory phenotypes. The data support a genetic effect on the inheritance of presbycusis in women and a mixed, genetically acquired cause in men.