McCune-Albright syndrome
The skeleton is made up of 206 bones in the adult and contributes to the form and shape of the body. The skeleton has several important fuctions for the body. The bones of the skeleton provide support for the soft tissues. For example, the rib cage supports the thoracic wall. Most muscles of the body are attached to bones which act as levers to allow movement of body parts. The bones of the skeleton also serve as a reservoir for minerals, such as calcium and phosphate. Finally, most of the blood cell formation takes places within the marrow of certain bones.
Also known as: Polyostotic fibrous dysplasia
- Bone fractures
- Deformities of the bones in the face
- Gigantism
- Irregular, large patchy café-au-lait spots, especially on the back
- Abnormal bone growth in the skull
- Abnormal heart rhythms (arrhythmias)
- Acromegaly
- Adrenal abnormalities
- Gigantism
- Hyperparathyroidism
- Hyperthyroidism
- Hypophosphatemia
- Large café-au-lait spots on the skin
- Liver disease, jaundice, fatty liver
- Ovarian cysts
- Pituitary or thyroid tumors
- Scar-like tissue in the bone (fibrous dysplasia)
- Adrenal hormones
- Blood prolactin
- Growth hormone
- MRI of the head
- X-rays of the bones
- Blindness
- Cosmetic problems from bone abnormalities
- Deafness
- Osteitis fibrosa cystica
- Premature puberty
- Repeated broken bones
- Tumors of the bone (rare)
Definition
McCune-Albright syndrome is a genetic disease that affects the bones and color (pigmentation) of the skin.
Causes, incidence, and risk factors
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:
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's 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.
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.
See also:
-
Symptoms
Hearing loss
Hearing loss is the total or partial inability to hear sound in one or both ears. See also:
-
Disease
Birthmarks - pigmented
A birthmark is a skin marking that is present at birth. Birthmarks include cafe-au-lait spots, moles, and mongolian spots. See also:
-
Disease
Osteitis fibrosa
Osteitis fibrosa is a complication of in which the bones turn soft and become deformed.
-
Symptoms
Blindness and vision loss
Blindness is a lack of vision. It may also refer to a loss of vision that cannot be corrected with glasses or contact lenses. Partial blindness means you have very limited vision. Complete blindness means you cannot see anything and do not see light. (Most people who use the term ...
-
Disease
Fibrous dysplasia
Fibrous dysplasia is a bone disease that destroys and replaces normal bone with fibrous bone tissue. One or more bones can be affected.
- Review date:
- September 10, 2010
- Reviewed by:
- Chad Haldeman-Englert MD, Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
Copyright Information
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2008 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.