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, 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.

Symptoms

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:

Signs 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 syndrome) may be treated with surgery to remove the adrenal glands. Gigantism and pituitary adenoma will need treatment with hormone inhibitors or surgery.

Expectations (prognosis)

Lifespan is relatively normal.

Complications

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.

Figures

Anterior skeletal anatomy

References

Garibaldi L, Chemaitilly W. Disorders of pubertal development. In: Kliegman RM, Stanton BF, St. Geme J, Behrman RE, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 556.

Revision

Last reviewed 7/8/2012 by Chad Haldeman-Englert MD, FACMG, Wake Forest School of Medicine, Department of Pediatrics, Section on Medical Genetics, Winston-Salem, NC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.

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