Mutations of the ACTH receptor gene are only one cause of familial glucocorticoid deficiency.

Familial glucocorticoid deficiency (FGD) is an autosomal recessive syndrome of failure of adrenal cortisol responsiveness to adrenocorticotropin (ACTH). Defects in the ACTH receptor have been suggested as a possible cause, and we have previously reported a point mutation in this gene in a family with FGD. Investigation of seven additional families has revealed a number of novel mutations in the ACTH receptor in some, but a normal gene in others suggesting that the aetiology of FGD may be heterogeneous. Using a highly polymorphic CA repeat marker (D18S40) closely linked to the ACTH receptor locus, we are now able to confirm that some cases of FGD result from defects at another locus. FGD provides an example of a single relatively homogeneous clinical syndrome resulting from two different molecular aetiologies.