Possible reasons for the lack of Sult1a1 loss of function studies maybe be due to previous investigations which either found through fine mapping of a lead obesity SNP (rs7359397) region no association of the SULT1A1 variants with BMI (27) or no change (hypothalamus) and opposing (liver and adipose) patterns of Sult1a1 mRNA expression in rats fed a HFD (28). The gene discussed is SULT1A1; the disease is obesity due to melanocortin 4 receptor deficiency.