Glucokinase Gene Mutation: Three Interesting Cases with Varied Phenotypic Presentations

Ambekar AN, Prathyusha S, Sethi BK and Modi KD

Published on: 2025-06-04

Abstract

The GCK gene encodes the glucokinase enzyme, and its mutations are linked to the maturity-onset diabetes of the young, Type 2 (MODY 2). This typically results in mild diabetes that often doesn't require medication for glycemic control. This report presents three cases of MODY 2 with different phenotypic presentations. The first case is a 35-year-old male with fasting hyperglycemia, one-sided small kidney, and proteinuria, confirmed to have GCK-type MODY. Renal problems appear non-diabetic. The second case is his 6-year-old daughter, who was misdiagnosed as Type 1 diabetes but later on found to have a heterozygous GCK mutation. Her insulin therapy was stopped, and at present, she is only on diet control with mild fasting hyperglycemia. Lastly, a 6-year-old boy with persistent neonatal diabetes on basal-bolus insulin therapy was identified with a homozygous inactivating GCK mutation. These cases highlight awareness about this condition in diverse phenotypic presentations.