McCune-Albright syndrome is a genetic disease that affects the bones and color (pigmentation) of the skin.
Polyostotic fibrous dysplasia
Causes, incidence, and risk factors
McCune-Albright syndrome is caused by mutations in the GNAS1 gene. A small number, but not all, of the patient’s cells contain this faulty gene (mosaicism).
This disease is not inherited.
The hallmark symptom of McCune-Albright syndrome is early puberty in girls. Menstrual periods may begin in early childhood, long before the breasts or pubic hair develop (which normally occur first). Puberty and menstrual bleeding may begin as early as 4 – 6 months in girls.
Early sexual development may also occur in boys, but not as often as in girls.
Other symptoms include:
- Bone fractures
- Deformities of the bones in the face
- Irregular, large patchy
café-au-lait spots, especially on the back
Signs and tests
A physical examination may show signs of:
Abnormal bone growth in the skull
Abnormal heart rhythms (
- Large café-au-lait spots on the skin
- Liver disease, jaundice, fatty liver
Ovarian cysts Pituitaryor thyroid tumors
- Scar-like tissue in the bone (
Tests may show too much:
Other tests that may be done include:
MRI of the head
X-rays of the bones
Genetic testing is available for the GNAS1 gene.
There is no specific treatment for McCune-Albright syndrome. Drugs that block estrogen production, such as testolactone, have been tried with some success.
Adrenal abnormalities (such as
Lifespan is relatively normal.
- Cosmetic problems from bone abnormalities
Deafness Osteitis fibrosa cystica
- Premature puberty
- Repeated broken bones
- Tumors of the bone (rare)
Calling your health care provider
Call your health care provider if your child starts puberty early, or has other symptoms of McCune-Albright syndrome. Genetic counseling, and possibly genetic testing, may be recommended if the disease is diagnosed.