Significant interactions comprising MDH1-rs2278718 and obesity (p for interaction = 0.0450), SUCLG2-rs902321 and severe obesity (0.0468), SUCLG2-rs35494829 and severe obesity (0.0457), SUCLG2-rs35494829 and abdominal obesity (0.0159), OGDHL-rs11101224 and abdominal obesity (0.0193), and OGDHL-rs751595 and abdominal obesity (0.0056) on rectal cancer were observed. This evidence concerns the gene MDH1 and obesity due to melanocortin 4 receptor deficiency.