Growth hormone-Insulin-like growth factor 1 axis hyperactivity on bone fibrous dysplasia in McCune-Albright Syndrome

McCune Albright syndrome (MAS) is a rare disorder caused by somatic gain-of-function mutations of the GNAS gene [1]. This gene encodes the α-subunit of the Gs protein and its mutations are responsible for persistent stimulation of adenylyl cyclase and dysregulated production of cyclic AMP leading to persistent overactivity in the target tissues. The extent of the disease is determined by the proliferation, migration and survival of the cell in which the mutation spontaneously occurs during embryonic development. Therefore, patients with GNAS mutations show a wide range of phenotypes, differing in the degree of severity and the age at onset of the disease. The disease is characterized by a variable association of café-au-lait skin spots, hyperfunctioning endocrinopathies and skeletal lesions with fibrous dysplasia involving one (monostotic) or multiple (polyostotic) bones.