DEMONSTRATION BY TRANSFECTION STUDIES THAT MUTATIONS IN THE ADRENOCORTICOTROPIN RECEPTOR GENE ARE ONE CAUSE OF THE HEREDITARY SYNDROME OF GLUCOCORTICOID DEFICIENCY

The hereditary syndrome of unresponsiveness to ACTH is a rare autosoma l recessive disorder characterized by low levels of serum cortisol and high levels of plasma ACTH. There is no cortisol response to exogenou s ACTH. Recent cloning of the human ACTH receptor gene has enabled us to study this gene in patients with glucocorticoid deficiency. By usin g the PCR to amplify the coding sequence of the ACTH receptor gene, we identified three mutations in two unrelated patients. One mutation pr esent in homozygous form converted the (107) located in the third tran smembrane domain, to an uncharged Ash residue. The second patient was a compound heterozygote: the paternal allele contained a one-nucleotid e insertion leading to a stop codon within the third extracellular loo p, and the maternal allele contained a point mutation converting Cys(2 51) to Phe, also in the third extracellular loop. Normal and mutant AC TH receptor genes were expressed in the M3 cell line, and intracellula r cAMP production in response to ACTH was measured. For the mutant rec eptors, no response to physiological ACTH concentrations was detected, suggesting an impaired binding of ACTH to the receptors and/or an alt ered coupling to the adenylate cyclase effector.