Neonatal diabetes: genetic implications in treatment

A 2-month-old newborn was diagnosed with diabetes mellitus presenting with ketoacidosis and negative islet antibodies. Genetic study revealed the R201C mutation of the KCNJ11 gene. In the last few years, the heterozygous activating mutation in KCNJ11 encoding the Kir6.2 subunit of the ATP-sensitive potassium (K(ATP)) channel has been shown to cause permanent neonatal diabetes. Diabetes results from impaired insulin secretion caused by failure of the beta cell-K(ATP) channel to close in response to increased intracellular ATP. Recent studies have demonstrated the effectiveness of oral sulfonylurea in the treatment of this disease. Sulfonylurea closes the K(ATP) channel by an ATP-independent route. Treatment with sulfonylurea in permanent neonatal diabetes has not yet been approved due to the lack of long-term studies in infants. However, the present case illustrates the importance of genetics to identify patients who may benefit from treatment.