Monogenic diabetes caused by inactivating mutation(s) in the GCK gene, encoding glucokinase. Heterozygous GCK mutations may manifest as mild hyperglycemia, which is not progressive, and usually requires no treatment. Homozygous GCK mutations result in permanent neonatal diabetes. The disease is MONDO_0007453 (maturity-onset diabetes of the young type 2). Also known as: GCK maturity-onset diabetes of the young (disease), GCK-associated diabetes mellitus, MODY 2 monogenic diabetes type 2, MODY glucokinase-related, MODY type 2, MODY, type II, MODY2, glucokinase-associated diabetes mellitus.