Familial Glucocorticoid Deficiency (FGD) syndrome is an adrenal insufficiency without mineralocorticoid deficiency. It is a genetic syndrome with low prevalence. Onset generally occurs during early infancy, but this syndrome can be diagnosed during childhood. It is marked by recurrent hypoglycemia (triggered, for example, by infectious episodes) that may lead to convulsions or even coma, chronic asthenia, frequent infections, susceptibility to allergies, and usually skin pigmentation. Plasma cortisol levels are very low or undetectable and do not respond to exogenous adrenocorticotropic hormone (ACTH), while plasma ACTH is very high, demonstrating that patients are specifically resistant to ACTH. Aldosterone and renin levels are usually normal and respond normally when the renin-angiotensin axis is activated. Adrenal hyperplasia due to enzymatic block, congenital X-linked adrenal hyperplasia and adrenoleukodystrophy are thus totally excluded. Mutations in the ACTH receptor gene have only been identified in a few affected patients (FGD type 1). There are one or several other genes that may be altered in the other patients, but they need to be identified. Treatment consists only of a replacement therapy with oral hydrocortisone/dexamethasone.
Last update: February 2005