Familial case of congenital hyperinsulinism associated with mutation in the GLUD1 gene

Congenital hyperinsulinism (CHI) is a rare hereditary disease characterized by hypoglycemia in children during the first year of life. Late diagnosis and inadequate therapy may result in severe neurological complications. Mutations in the GLUD1 gene that encodes glutamate dehydrogenase are one of the causes of CHI. This form of CHI is characterized by protein-induced hyperinsulinemic hypoglycemia and hyperammonemia in patients. Diagnosing can be challenging because hyperinsulinemic hypoglycemia cannot be detected using the conventional fasting glucose test. Extensive examination including the protein load test is needed to refine diagnosis. We report a familial case where the mother and two daughters were diagnosed with CHI and had a mutation in the catalytic domain of the GLUD1 gene. The clinical presentation, the laboratory data, the outcome of therapy, and the dynamic follow up data for the patients are presented.