CETP and obesity due to melanocortin 4 receptor deficiency: In the adult population, DM2 and obesity have been shown to profoundly affect HDL metabolism and lead to changes in HDL composition and a shift towards small HDL3 particles (58, 59), as well as marked changes in cholesteryl ester transfer protein (CETP) and lecithin–cholesterol acyltransferase (LCAT) activities (59).