ACTH-independent Cushing's syndrome due to ectopic endocrinologically functional adrenal tissue caused by a <i>GNAS</i> heterozygous mutation: a rare case of McCune-Albright syndrome accompanied by central amenorrhea and hypothyroidism: a case report and literature review. The gene discussed is GNAS; the disease is Cushing syndrome due to macronodular adrenal hyperplasia.