Abstract P255: Genetic Variation in Chromosome 8p23 is Associated With Sedentary Behavior in Humans

Sedentary behavior, usually quantified as sitting time, has been shown to be associated with several adverse health outcomes, even among individuals who meet the current recommendations for physical activity. Both twin and family studies have shown that sedentary behavior aggregates in families and is a heritable trait. However, little is known about genes and DNA sequence variants that contribute to propensity to be sedentary. The purpose of our study was to conduct a genome-wide association study to identify genomic regions and DNA sequence variants associated with sedentary time. A total of 67,530 Caucasians (56% female, mean age 62.1 years [SD 12.5]) from the Kaiser Permanente Research Program on Genes, Environment, and Health (RPGEH) cohort were used for the discovery analyses. Other RPGEH ethnicities (African-Americans: N=2,500; East Asians: N=6,300; Hispanics: N=8,800) were used for replication studies. Information on daily sitting time outside of work was obtained by a questionnaire. A custom panel of 657,184 autosomal single nucleotide polymorphisms (SNPs) was genotyped using Affymetrix platform. Associations between sedentary time (dichotomized; cases 3 hours or more, controls less than 3 hours per day) and the SNPs were tested with PLINK logistic model using age, sex, BMI and admixture principal components as covariates. The strongest evidence of association was detected on chromosome 8p23.1. A total of 24 SNPs within a 1.34 Mb region were associated with sedentary time at genome-wide significance level (p<5x10 -8 ), with SNP rs11774552 showing the peak association (OR=0.924, p= 1.7x10 -12 ). Sex-specific analyses confirmed that the associations were present both in men and women. The same SNPs were not associated with sedentary time in other ethnicities. However, SNP rs28754712, which is located in the immediate vicinity (+456 bp) of rs11774552, showed a significant association with sedentary time (OR=0.795, p=1.2x10 -3 ) in African-Americans. In summary, our results provide the first evidence of genomic region and DNA sequence variants associated with sedentary behavior in humans. If confirmed in additional replication studies, these findings will advance our understanding of biological mechanisms contributing to propensity to be sedentary.