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McCune-Albright syndrome

Definition

McCune-Albright syndrome is a genetic disease that affects the bones, hormones, and color (pigmentation) of the skin.

Alternative Names

Polyostotic fibrous dysplasia

Causes

McCune-Albright syndrome is caused by mutations in the GNAS gene. A small number, but not all, of the person's cells contain this faulty gene (mosaicism).

This disease is not inherited.

Symptoms

The main 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). The average age that symptoms appear is 3 years old. However, puberty and menstrual bleeding have occurred as early as 4 to 6 months in girls.

Early sexual development may also occur in boys, but not as often as in girls.

Other symptoms include:

Exams and Tests

A physical examination may show signs of:

  • Abnormal bone growth in the skull
  • Abnormal heart rhythms (arrhythmias)
  • Acromegaly
  • Gigantism
  • Large cafe-au-lait spots on the skin
  • Liver disease, jaundice, fatty liver
  • Scar-like tissue in the bone (fibrous dysplasia)

Tests may show:

Other tests that may be done include:

Genetic testing may be done to confirm the diagnosis.

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 to be treated with medicines that block hormone production, or with surgery.

Bone abnormalities (fibrous dysplasia) are sometimes removed with surgery.

Limit the number of x-rays taken of affected areas of the body.

Outlook (Prognosis)

Lifespan is relatively normal.

Possible Complications

Complications may include:

When to Contact a Medical Professional

Contact 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 suggested if the disease is detected.

Gallery

Skeletal spine
The spine is divided into several sections. The cervical vertebrae make up the neck. The thoracic vertebrae comprise the chest section and have ribs attached. The lumbar vertebrae are the remaining vertebrae below the last thoracic bone and the top of the sacrum. The sacral vertebrae are caged within the bones of the pelvis, and the coccyx represents the terminal vertebrae or vestigial tail.
Acanthosis nigricans - close-up
This photograph demonstrates the hyperpigmented, brownish, velvety lesions of acanthosis nigricans. This skin condition may occur in skin folds such as the axilla (armpit - pictured here), neck, and other areas. In adults, it may be associated with hormonal problems, internal malignancy, obesity, and drugs.

References

Garibaldi LR, Chemaitilly W. Disorders of pubertal development. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 578.

Styne DM. Physiology and disorders of puberty. In: Melmed S, Auchus RJ, Goldfine AB, Koenig RJ, Rosen CJ, eds. Williams Textbook of Endocrinology. 14th ed. Philadelphia, PA: Elsevier; 2020:chap 26.

Last reviewed July 26, 2022 by Anna C. Edens Hurst, MD, MS, Associate Professor in Medical Genetics, The University of Alabama at Birmingham, Birmingham, AL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team..

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