A Novel Glucokinase Mutation Causing Maturity-onset Diabetes of the Young: A Case Report

Maturity-onset diabetes of the young (MODY) is a group of monogenic disorders characterized by early-onset, non-insulin-dependent diabetes mellitus, typically inherited in an autosomal dominant manner. MODY type 2 (MODY2), also known as glucokinase-MODY (GCK-MODY), results from mutations in the GCK gene. Unlike type 1 and 2 diabetes, MODY is generally mild and has a different pathophysiology. This case report describes a 3-year-old boy diagnosed with MODY2 who presented with elevated fasting blood glucose levels in the absence of ketosis. His family history revealed diabetes spanning three consecutive generations, with his mother having a history of gestational diabetes mellitus (GDM). Whole-exome sequencing identified a heterozygous mutation in the GCK gene (c.1007C > A (p.Ser336*)) in the patient and his mother. The diagnosis of MODY2 allowed for tailored management, with blood glucose levels successfully controlled through dietary regulation and appropriate exercise without pharmacological intervention. This report underscores the importance of genetic testing in pediatric hyperglycemia cases to avoid unnecessary treatment.