Genetically, there is a spontaneous postzygotic mutation of the gene GNAS, on the long (q) arm of chromosome 20 at position 13.3, which is involved in G-protein signaling. This mutation, which occurs only in the mosaic state, leads to constitutive receptor signaling and inappropriate production of excess cAMP. The mutation that causes<unk>  arises very early during embryogenesis. Because all cases of the syndrome are sporadic, it is believed that the mutation would be lethal if it affected all cells in the embryo. Mutant cells can only survive when they are intermixed with normal cells. There are no known risk factors for acquiring<unk> , and no exposures during pregnancy that are known to either cause or prevent the mutation from occurring. The disease cannot be inherited and occurs equally among all ethnic groups.
McCune–Albright syndrome
Lightwood–Albright syndrome
Alström syndrome
Young–Madders syndrome
Multiple endocrine neoplasia type 1
Wilson–Turner syndrome
Multiple endocrine neoplasia type 2
Wolcott–Rallison syndrome