Genome-wide DNA methylation analysis in blood identifies differentially methylated regions related to polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is considered a multifactorial disorder caused due to predisposing alleles of various genes and environmental factors which include lifestyle, dietary habits, and exposure to toxicants. Recently the emphasis has shifted to understanding epigenetic alterations due to the poor correlation between genotypes and the clinical profile of women with PCOS. Investigators have been focusing on differential methylation signatures associated with PCOS, therefore, a pilot study was carried out to investigate PCOSassociated differential DNA methylation regions in the population of north India. A cross-sectional study with sixteen participants comprising eight women with PCOS diagnosed under the Rotterdam criterion and eight age and BMI-matched healthy controls. Subjects were classified into four groups based on BMI and two different groups were compared each time making four comparison types in total. Genome-wide DNA methylation in whole blood was evaluated using an Infinium Human Methylation 850k array which identified PCOS-associated differential sites and differential methylation regions (DMRs) with promoter region, and CpG islands considering ( p <= 0.01) as statistically significant. Multiple significantly associated hypomethylated and hypermethylated loci of genes were identified. Thirty-four hypomethylated and one hundred twenty-six hypermethylated sites of genes were suggested when all the subjects were of low BMI. But when the groups comprised with high BMI, twentyseven hypomethylated genes and fifty-nine hypermethylated genes were identified. In silico analysis suggests that most of these genes are involved in estrogen biosynthesis, lipid biosynthetic process, and activation of matrix metalloproteinases (MMP). Seven genes that are found common in both of these comparisons are mostly involved in the inflammasome pathway indicated by BioPlanet and Reactome databases. The study provides information about DMRs in the blood tissue which may be investigated further to understand underlying pathogenesis and as therapeutic targets in the future.