GPT and obesity due to melanocortin 4 receptor deficiency: The investigated traits were plasma triglyceride levels, traits related to obesity (BMI and waist circumference (WC)), glucose metabolism (glycated haemoglobin (HbA1c)) and chronic inflammation (hs-CRP), and, for the first time, crude estimates of the presence of liver fat (the liver enzymes gamma-glutamyltransferase (GGT) and alanine amino transferase (ALT) [34], [35]), and fetuin-A, a biomarker which has been associated with fat accumulation in the liver [36]–[40] as well as with insulin resistance, type 2 diabetes and cardiovascular events [40]–[42].