Figure 5
From: McCune-Albright syndrome
Molecular defect and phenotype in McCune-Albright syndrome (MAS). The hormones MSH (melanocyte stimulating hormone), LH (luteinizing hormone), TSH (thyroid stimulating hormone), GHRH (growth hormone stimulating hormone), and ACTH (adrenocrotical stimulating hormone) all signal through the G protein (alpha, beta, gamma subunits) pathway. In MAS, the alpha subunit is mutated in such a way as to induce constitutive activation of adenylate cyclase, and thus produce high levels of intracellular cAMP. This results in increased production of melanin, estradiol (E2), testosterone (T), thyroxine (T4), growth hormone (GH), and cortisol. Dysregulated production of these hormones results in café-au-lait spots, precocious puberty, fibrous dysplasia, acromegaly, hyperthyroidism, and Cushing's disease, depending on the tissue harboring the somatic mutation.