Follow up of a rare case of adrenal insufficiency due to NNT mutation.

Hypoglycaemia is one of the most common causes of convulsions in neonatal period. Repeated hypoglycaemic convulsions have to be addressed with utmost urgency to prevent its morbid sequelae. Repeated ketotic hypoglycaemia in the infantile period needs detailed endocrine evaluation. Our patient is a boy in the third year of his life, had presented in infancy with hypoglycaemic convulsions and hyperpigmentation of skin and mucous membrane. Investigations revealed ketotic hypoglycaemia, hypocortisolaemia with high adrenocorticotropic hormone (ACTH) and normal aldosterone, 17-hydroxyprogesterone (17-OHP) and testosterone levels. This suggested isolated glucocorticoid deficiency without mineralocorticoid deficiency. He responded well to hydrocortisone therapy with resolution of symptoms and normalisation of lab parameters. Genetic study confirmed the diagnosis of familial glucocorticoid deficiency (FGD) with homozygous mutation in NNT (nicotinamide nucleotide transhydrogenase) gene with a novel p.Thr578lle variant. This is the first case of FGD with NNT mutation to be reported from the Indian subcontinent.