Abstract LB-379: A targeted, next-generation bisulfite sequencing approach to evaluate the influence of maternal pre-pregnancy body mass index and gestational weight gain on umbilical cord blood DNA methylation levels
Authors: Clarke Megan A. , Esopi David , Yegnasubramanian Srinivasan , Platz Elizabeth A. , Joshu Corinne E. 
Published: July 2016

Abstract
Introduction: Offspring born to obese mothers and/or mothers who gain excess weight during pregnancy are at increased risk of obesity and metabolic disease later in life, both of which are risk factors for certain cancers. While the biological mechanisms underlying these associations are not well understood, evidence from animal models and limited data from human studies suggests that DNA methylation may play an important role. Thus, we evaluated the association of maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) with DNA methylation in umbilical cord blood DNA using a candidate gene approach.
Methods: This study includes 112 black and white mothers and their neonates in the Hormones in Umbilical Cord Blood Extended Study. Participants were enrolled in 2006-2007 from a prenatal clinic in Baltimore, MD. Self-reported, pre-pregnancy BMI was categorized as normal (&lt;25.0 kg/m2), overweight (25.0 to &lt;30.0 kg/m2) or obese (?30 kg/m2). GWG was obtained from the medical record and categorized with respect to pre-pregnancy BMI, according to U.S. guidelines. Data on demographics, lifestyle, and pregnancy characteristics were obtained from a prenatal questionnaire and the medical record. Candidate genes were chosen based on literature review (n = 29) and those genes related to obesity and cancer were prioritized. Cord blood leukocyte DNA methylation at these genes was quantified using bisulfite sequencing carried out with high-throughput, microfluidic PCR of bisulfite-converted DNA followed by next-generation sequencing. Generalized linear models with a binomial distribution were fit to assess associations of pre-pregnancy BMI (overweight/obese vs. normal) and GWG (more than vs. within/less than recommended) with DNA methylation. Models were adjusted for maternal and gestational age, smoking, parity, race, and infant sex. We adjusted p-values for the false discovery rate (FDR) and stratified all significant results by maternal race and infant sex.
Results: A total of 29 CpG sites in 14 genes were differentially methylated with respect to pre-pregnancy BMI (FDR p-value ?0.05). A total of 30 CpG sites in 15 genes were differentially methylated with respect to GWG (FDR p-value ?0.05). Four CpG sites were significantly differentially methylated in the same direction with respect to both maternal pre-pregnancy BMI and GWG (ANAPC7, CAB39, HEYL and SAPCD2). We observed differences by race and sex. In particular, in males, pre-pregnancy overweight/obesity and excess GWG were associated with increased DNA methylation patterns at a majority of the significant CpG sites.
Discussion: To our knowledge this study is one of the first to use targeted, next-generation bisulfite sequencing to quantify methylation in cord blood DNA. Our findings suggest maternal adiposity and GWG may influence DNA methylation of offspring genes, in a sex-specific manner. These findings warrant replication in large, prospective studies.
Funding: NCI T32 CA009314, P30 CA006973, U54 CA091409, and the JHSPH Doctoral Thesis Research Fund.
We wish to acknowledge Dr. Sarah Wheelan and Jennifer Meyers from the SKCCC Next Generation Sequencing Lab
Citation Format: Megan A. Clarke, David Esopi, Srinivasan Yegnasubramanian, Elizabeth A. Platz, Corinne E. Joshu. A targeted, next-generation bisulfite sequencing approach to evaluate the influence of maternal pre-pregnancy body mass index and gestational weight gain on umbilical cord blood DNA methylation levels. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-379.