McCune-Albright syndrome
Definition
McCune-Albright syndrome is a genetic disease that affects the bones and color (pigmentation) of the skin.
Alternative Names
Polyostotic fibrous dysplasia
Causes
McCune-Albright syndrome is caused by mutations in the GNAS1 gene. The abnormal gene is present in a fraction, but not all, of the patient's cells (mosaicism).
This disease is not inherited. It is caused by a new change (mutation) to the DNA that occurs in the womb while the baby is developing. This mutation is not passed on to any of the person's children.
Symptoms
The hallmark symptom of McCune-Albright syndrome is premature 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 it is not as common as it is in girls.
Other symptoms include:
Exams and Tests
A physical examination may show signs of:
Tests may show too much:
Other tests that may be done include:
Genetic testing is available for the GNAS1 gene.
Treatment
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 Cushing's syndrome
) may be treated with surgery to remove the adrenal glands. Gigantism and pituitary adenoma will need treatment with hormone inhibitors or surgery.
Outlook (Prognosis)
Lifespan is relatively normal.
Possible Complications
When to Contact a Medical Professional
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.
References
Garibaldi L. Disorders of Pubertal Development. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics
. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 563.
Review Date: 8/7/2008
Reviewed By: Diana Chambers, MS, EdD, Certified Genetics Counselor (ABMG), Charter Member of the ABGC, University of Tennessee, Memphis, TN. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
