The most commonly diagnosed variant—MODY3—caused by a mutation in the hepatocyte nuclear factor 1-alpha (HNF1A) gene, accounts for roughly 69% of MODY cases, while the other two predominant types, glucokinase (GCK) and HNF4A, contribute to approximately 20% and 3%, respectively [2,4,5,6]. The gene discussed is GCK; the disease is maturity-onset diabetes of the young type 3.