Genetic and environmental influences in sleep-disordered breathing in older male twins.

STUDY OBJECTIVES To estimate the extent to which genetic factors contribute to the variation in several indices of sleep-disordered breathing in elderly male twins. DESIGN AND SETTING A biometric genetic study based on data from unattended Edentrace recordings in a sample of elderly male twins. PARTICIPANTS 122 World War II male veteran twin pairs, including 68 monozygotic pairs aged 78.9 (+/- 2.7) years and 54 dizygotic pairs aged 78.4 (+/- 2.4) years. INTERVENTIONS N/A. MEASUREMENTS AND RESULTS The average (+/- SD) respiratory disturbance index for this sample was 17.2 +/- 14.5, the average (+/- SD) oxygen desaturation index was 18.8 +/- 16.4, and the average (+/- SD) minimum SaO2 level was 79.6 +/- 8.1%. Intraclass twin-pair correlations for log-transformed respiratory disturbance index were 0.59 in monozygotic pairs and 0.36 in dizygotic pairs. For oxygen desaturation index, intraclass correlations were 0.44 in monozygotic pairs and 0.24 in dizygotic pairs. For minimum SaO2, intraclass correlations were 0.38 and 0.11, respectively. Maximum likelihood estimates of heritability with associated 95% confidence intervals were 37% [22%, 52%] for respiratory disturbance index, 36% [19%, 53%] for oxygen desaturation index, and 10% [0%, 30%] for minimum SaO2. Adjustments of sleep-disordered breathing measures for age, body mass index, and waist and neck circumference had minimal effect on estimates of heritability. CONCLUSIONS The present data indicate that sleep-disordered breathing, even in old age, is determined, in part, by genetic factors.