McCuneAlbright
McCune-Albright syndrome, often abbreviated MAS, is a rare disorder characterized by fibrous dysplasia of bone, café-au-lait skin pigmentation, and autonomous endocrine abnormalities. It results from activating mutations in the GNAS gene encoding the α subunit of the stimulatory G protein (Gsα), which occur postzygotically in a mosaic pattern. Because the mutation is somatic, MAS is not typically inherited and shows variable expression among tissues.
Clinically, MAS most often presents with polyostotic fibrous dysplasia causing bone pain, deformities, and fracture risk.
Endocrine features include precocious puberty, particularly in girls, due to autonomous ovarian estrogen production independent of
Diagnosis is based on the clinical triad, imaging showing fibrous dysplasia, and genetic testing when available;
Management is multidisciplinary, focusing on monitoring and treating fractures, deformities, and endocrinopathies. There is no cure;