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Alternative namesPolyostotic fibrous dysplasia
DefinitionMcCune-Albright syndrome is a genetic disease affecting the bones and pigmentation of the skin, which also causes hormonal problems and premature sexual development.
Causes, incidence, and risk factors
The hallmark of McCune-Albright syndrome is premature puberty in the female. Menstrual periods may begin in early childhood, long before the appearance of breast or pubic hair development, which normally occur first. Early sexual development may also occur in males, but this is not as common as in females.
McCune-Albright syndrome is caused by mutations in the GNAS1 gene. It is associated with mosaicism, meaning that the abnormal gene is present in a fraction, but not all, of the patient's cells. This disease is not inherited, it is sporadic. This means that a new mutation of the DNA occurs in the womb during development of the patient. This mutation is not passed on to any children the patient later has.
Signs and testsA physical examination may show signs of:
Tests may show signs of hyperthyroidism, hyperparathyroidism, excess adrenal hormones, or excess blood prolactin or growth hormone.
X-rays show fibrous dysplasia that affects multiple bones. An MRI of the head may show a type of tumor called an adenoma in the pituitary gland. Genetic testing may be available for the GNAS1 gene.
There is not a specific treatment for McCune-Albright syndrome. Drugs that inhibit estrogen production, such as testolactone, have been tried with some success.
Adrenal abnormalities (such as Cushing's syndrome ) may be treated by surgery to remove the adrenal glands . Gigantism and pituitary adenoma will require treatment with hormone inhibitors or surgery.
Expectations (prognosis)Longevity is relatively normal.
Calling your health care providerCall your health care provider if your child develops evidence of premature puberty (before the expected age) or has other symptoms suggestive of McCune-Albright syndrome. Genetic counseling, and possibly genetic testing, may be recommended if the disease is diagnosed.
Update Date: 11/8/2002David G. Brooks, M.D., Ph.D., Division of Medical Genetics, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.
Last updated: Tue, 06 Jan 2009 00:20:03 GMT