Hereditary adrenocortical unresponsiveness to adrenocorticotropin with a postreceptor defect

We report two cases in one pedigree with hereditary adrenocortical unresponsiveness to ACTH (HACUA) where it is suggested that the pathogenic defect occurs after cAMP generation. Although the patients showed increased plasma ACTH, decreased plasma cortisol and dehydroepiandrosterone, and no steroidogenic response to exogenous ACTH, they responded normally to both furosemide administration and to a low sodium diet by showing increases in plasma aldosterone. The peripheral blood mononuclear leukocytes (MNLs) from these patients possessed ACTH receptors similar to adrenocortical ones, which was in contrast to a previously reported case with a deficiency of ACTH receptors in the MNLs. Furthermore, ACTH receptors in the patients' MNLs were functionally coupled to adenylate cyclase. Dibutyryl cAMP infusion did not, however, increase plasma cortisol nor aldosterone in these patients in a sharp contrast to its remarkable increase in a normal control subject. These results suggest that these patients represent a new subtype of HACUA with a failure of intracellular reception of the cAMP message in adrenocortical cells. We propose to classify our patients with a postreceptor defect as HACUA type II using an analogy to pseudohypoparathyroidism type II.