GCK and MODY: Almost all MODY cases are attributable to highly penetrant variants in the four most common MODY genes, namely, MODY1, 2, 3, and 5 (specifically hepatocyte nuclear factor 4-alpha (HNF4α; MODY1), glucokinase (GCK; MODY2), hepatocyte nuclear factor 1-alpha (HNF1α; MODY3), and hepatocyte nuclear factor 1-beta (HNF1β; MODY5)) in Caucasians [12].