McCune-Albright syndrome (MAS), is a genetic disease also known as familial gonadotropin-independent precocity. It affects the bones (fibrous dysplasia) and skin (cafe au lait spots), and causes precocious puberty, particularly early menarche in females.

MAS is believed to be caused by mutations in the GNAS1 gene. While there is no specific cure, it should be treated with drugs that inhibit gonadal steroidogenesis or gonadal steroid action to preserve fertility.

In girls, tamoxifen and bisphosphonate pamidronate have been shown to be helpful. Boys have been treated with ketoconazole (inhibits androgen synthesis), or a combination of spironolactone, (inhibits androgen action) and testolactone (blocks the conversion of androgen to estrogen), with good results.

Complications included broken bones, cosmetic bone deformities, blindness/deafness (pinched nerves as a result of bone deformities).