TCN1 and obesity due to melanocortin 4 receptor deficiency: Starting with protein intake, the most commonly investigated dietary factor among the studies, a cross-sectional interaction study of 109 healthy Sinhalese adults from the Genetics of Obesity and Diabetes cohort (GOOD) found that protein–energy intake (%) significantly interacted with a B12-GRS consisting of MTHFR, CPS1, CUBN, CD320, TCN2, CLYBL, FUT2, TCN1, FUT6, and MUT variants and a metabolic-GRS based on FTO, MC4R, TCF7L2, KCNJ11, and CAPN10 variants influencing obesity risk.68