Adrenal hypoplasia congenita in identical twins.

We are presenting a monozygotic twin brothers presented at different ages with different presentations. Twin-A presented at age of 18 days with salt losing crisis. Investigations revealed high plasma renin with low-normal aldosterone. Adrenocorticotropic hormone, stimulation test revealed low 17-OH progesterone at 0 and 60 minutes. Adrenocorticotropic hormone level and serum cortisol were normal, which excluded initial impression of congenital adrenal hyperplasia. He was diagnosed to have isolated primary hypoaldosteronism. At age of 18 months, he was noticed to have hyperpigmentation of lips and gum. Adrenal failure was suspected, and hydrocortisone was added. Twin-B presented at 9 years and 6 months of age with adrenal crisis. Both were having unilateral undescended testes. Adrenal hypoplasia congenita (AHC) was suspected after his twin's presentation.  Molecular analysis for gene study for both of them revealed adrenal insufficiency, NR0B1 (DAX1) gene mutation. In conclusion, gene analysis is important for the diagnosis of AHC and for genetic counseling.