McCune-Albright Syndrome

McCune-Albright syndrome (MAS) is a rare noninherited genetic disorder which typically manifests as the classic triad of precocious puberty (PP), café-au-lait (CAL) skin macules, and fibrous dysplasia (FD) of bone. It is caused by a gain of function mutation in the GNAS1 gene leading to autonomous activation of intracellular signaling pathways. As the mutation is present in a mosaic distribution in endocrine cells and other tissues, presentations are highly variable. In this chapter, we describe the endocrinopathies in MAS that affect the gonads, thyroid, pituitary, and adrenals, as well as review the skin manifestations and bone disease. Treatment options for PP in affected girls include aromatase inhibitors (AIs) and estrogen receptor modulators. Further studies are needed to better define the underlying pathophysiologic triggers for specific endocrine manifestations and to optimize clinical management.