To the Editor: Cortisol-producing adrenocortical tumors have been associated with abnormalities of the cyclic AMP (cAMP)–signaling pathway. Examples are Cushing's syndrome in infants with the McCune–Albright syndrome due to adrenocortical adenomas that harbor mutations of the stimulatory subunit alpha of G proteins (GNAS), primary pigmented nodular adrenocortical disease due to mutations of the protein kinase A regulatory subunit type 1A (PRKAR1A), and macronodular adrenocortical disease associated with aberrant expression of G-protein–coupled receptors in the tumor tissue.¹,² Recently, we performed a genomewide search for genes conferring a predisposition to micronodular adrenocortical hyperplasia, leading to Cushing's syndrome . . .