Supplementary Material for: Methylation Status of CYP27B1 and IGF2 Correlate to BMI SDS in Children with Obesity

<p><b><i>Objective:</i></b> Worldwide increasing childhood obesity is due to interactions between environmental and genetic factors, linked together by epigenetic mechanisms such as DNA methylation. <b><i>Methods: </i></b>82 obese children (>95th BMI percentile , age: 3-18 years) were included. Anthropometric data, metabolic parameters, 25-OH vitamin D (25OHD), and pubertal status were recorded, 24-hour blood pressure monitoring was performed. BMI standard deviation score (SDS) was calculated. Using candidate gene approach, obesity- (insulin-like growth factor 2 (<i>IGF2</i>), proopiomelanocortin (<i>POMC</i>)) and vitamin D metabolism-related genes (1-alfa-hydroxylase (<i>CYP27B1</i>), <i>VDR</i>) regulated by DNA methylation were selected. After isolating DNA from peripheral blood, bisulfite conversion, bisulfite specific polymerase chain reaction (BS-PCR), and pyrosequencing were carried out. <b><i>Results: </i></b>No significant correlation between 25-OHD and metabolic parameters and DNA methylation status, but a tendency of positive correlation between VDR methylation status and 25-OHD (r = 0.2053,p = 0.066) were observed. Significant positive correlations between BMI SDS and <i>CYP27B1</i> hypermethylation (r = 0.2371,p = 0.0342) and a significant negative correlation between <i>IGF2 </i>hypomethylation and BMI SDS (r = -0.305,p = 0.0059) were found. <b><i>Conclusions </i></b>Rate of obesity shows correlation with DNA methylation. Hypomethylation of <i>IGF2</i> and hypermethylation of <i>CYP27B1</i> genes might positively influence the rate of BMI observed in obese children.</p>