Environment-wide and epigenome-wide association study of adiposity in "Children of 1997" birth cohort

Abstract

BackgroundIncreasing childhood adiposity is a global issue requiring potentially local solutions to ensure it does not continue into adulthood. We systematically identified potentially modifiable targets of adiposity at the onset and end of puberty in Hong Kong the most economically developed major Chinese city. MethodsWe conducted an environment-wide association study (EWAS) and an epigenome-wide association study of adiposity to systematically assess associations with body mass index (BMI) and waist-hip ratio (WHR) in Hong Kongs population-representative "Children of 1997" birth cohort. Univariable linear regression was used to select exposures related to adiposity at ~11.5 years (BMI n[≤]7,119, WHR n=5,691) and ~17.6 years (n = 3,618) at Bonferroni-corrected significance, and multivariable linear regression to adjust for potential confounders followed by replication (n=308) and CpG by CpG analysis (n=286) at ~23 years. Findings were compared with evidence from randomized controlled trials (RCTs) and Mendelian randomization (MR) studies. ResultsAt ~11.5 and ~17.6 years the EWAS identified 14 and 37 exposures associated with BMI, as well as seven and 12 associated with WHR respectively. Most exposures had directionally consistent associations at ~23 years. Maternal second-hand smoking, maternal weight, and birth weight were consistently associated with adiposity. Diet (including dairy intake and artificially sweetened beverages), physical activity, snoring, binge eating, and earlier puberty were positively associated with BMI at ~17.6 years, while eating before sleep was inversely associated with BMI at ~17.6 years. Findings for birth weight, dairy intake, binge eating, and possibly earlier puberty are consistent with available evidence from RCTs or MR studies We found 21 CpGs related to BMI and 18 to WHR. ConclusionsThese novel insights into potentially modifiable factors associated with adiposity at the outset and the end of puberty could, if causal, inform future interventions to improve population health in Hong Kong and similar Chinese settings. FundingThis study was supported by the Health and Medical Research Fund Research Fellowship, Food and Health Bureau, Hong Kong SAR Government (#04180097). The DNA extraction was supported by CFS-HKU1.