Hepatic resistance to FGF19 in obesity and insulin resistance has been described.[7, 25] To examine this effect in our cohort we looked at the C4/FGF19 ratio (high values reflecting loss of enterohepatic feedback) and the C4*FGF19 product (as a measure of hepatic resistance). This evidence concerns the gene FGF19 and obesity due to melanocortin 4 receptor deficiency.