A Study of The Relationship between The Interleukin-6 Gene and Obstructive Sleep Apnea

Because obstructive sleep apnea (OSA) is associated with increased levels of inflammatory cytokines, we examined the relationship between OSA and polymorphisms for interleukin-6 (IL6). Six single nucleotide polymorphisms (SNPs) within IL6 were genotyped in 259 African Americans from the Cleveland Family Study with replication conducted in the Cardiovascular Health Study (n= 124). OSA was dichotomized into apnea hypopnea index (AHI) > 15, or on treatment versus absent: AHI < 5. Logistic regression was conducted, adjusting for age and sex in models with and without body mass index (BMI). SNP IL6-6021 was associated with a decreased risk of OSA after adjusting for BMI (Odds Ratio for T allele 0.24, 95%CI [0.09-0.67], p= 0.006, q= 0.07) under an additive model. This same allele was associated with increased BMI. The results from the replication sample were consistent in direction though not statistically significant (p= 0.23). The SNPs were studied in European- Americans, although, the minor allele frequency in IL6-6021 was too low (4%) for meaningful comparisons. A synonymous SNP within the IL6 coding region was protective of OSA in African Americans; with qualitatively similar findings observed in another cohort. This suggests that variants in IL6 may influence the risk of OSA in a pathway that is not explained by obesity. Clin Trans Sci 2010; Volume 3: 337-339.