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.

Rare cause of recurrent hypocalcaemia and functional hypoparathyroidism due to hypomagnesaemia caused by TRPM6 gene mutation.

Magnesium is essential for the functioning and release of parathyroid hormone. Therefore, its deficiency can present as functional hypoparathyroidism. This case report describes a rare inherited disorder called congenital hypomagnesaemia with secondary hypocalcaemia due to TRPM6 gene mutation. This disease clinically and biochemically mimics hypoparathyroidism. However, unlike hypoparathyroidism, it can be treated only by long-term oral magnesium supplements. The patient presented to us with recurrent hypocalcaemic convulsions. The laboratory picture in each admission was similar to that of hypoparathyroidism. However, the hypocalcaemia persisted, and it was noticed to be associated with persistent hypomagnesaemia. A defect in the tubular magnesium reabsorption was postulated and a genetic analysis of the patient was done, which revealed a TRPM6 mutation causing hypomagnesaemia by excessive renal excretion of magnesium. The child responded well to oral magnesium supplements and is currently developmentally appropriate for her age and thriving well.

Rare cause of persistent hypocalcaemia in infancy due to PTH gene mutation.

Hypocalcaemia is a frequently encountered electrolyte abnormality in neonates and it is mostly transient. However, persistent hypocalcaemia can point towards an endocrine abnormality like hypoparathyroidism, which is usually due to genetic disorders like DiGeorge and Kearns Sayre syndrome or due to mutations of genes like GCM2, CaSR and PTH.Our patient was a female child, who presented with hypocalcaemic convulsions in the neonatal period. On laboratory assessment, serum phosphate levels were noted to be high along with inappropriately low parathyroid hormone (PTH) levels. The child was diagnosed to have hypoparathyroidism and was started on oral calcium and 1,25-dihydroxycholecalciferol supplements to which she responded well. However, the child was lost to follow-up and was readmitted with hypocalcaemic convulsions in infancy. Clinical exome analysis done was diagnostic of homozygous PTH gene mutation. This case demonstrates a rare form of congenital isolated hypoparathyroidism with no other syndromic associations.