Question: How many people are affected by McCune-Albright syndrome ?
Answer: McCune-Albright syndrome occurs in between 1 in 100,000 and 1 in 1,000,000 people worldwide.
Source: GHR

Question: Is McCune-Albright syndrome inherited ?
Answer: McCune-Albright syndrome is not inherited. Instead, it is caused by a random mutation in the GNAS gene that occurs very early in development. As a result, some of the body's cells have a normal version of the GNAS gene, while other cells have the mutated version. This phenomenon is called mosaicism. The severity of this disorder and its specific features depend on the number and location of cells that have the mutated GNAS gene.
Source: GHR