McCune-Albright syndrome
Background
McCune-Albright syndrome (MAS) is a rare condition that was first described in 1937. It is sometimes called Albright syndrome.
The classic presentation of this syndrome consists of 3 features:
- Café-au-lait spots on the skin
- Bone abnormalities
- Endocrine (hormonal) abnormalities, in particular early puberty
At least 2 of these features need to be present to diagnose the condition. MAS is a genetic condition that is caused by a spontaneous (chance) mutation in the GNAS1 gene. The mutation occurs early in the development of an embryo and affects only a subset of the patient's cells (called mosaicism). The mutation cannot be passed on to affected patient's children.
Clinical features
| 1. Café-au-lait spots |
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| 2. Bone abnormalities |
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| 3. Endocrine abnormalities |
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| 4. Other associated problems |
MAS has been associated with a variety of other clinical problems including:
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Diagnosis
- X-rays of the affected bones show characteristic features such as a central ‘ground-glass’ pattern, lytic lesions (local disappearance of normal bone), cyst-like appearance, and evidence of current or past fractures.
- CT, MRI, and nuclear medicine bone scanning may also be useful.
- Once the condition has been diagnosed, other investigations are required to screen for occult (concealed) endocrine abnormalities.
Treatment
- Medical treatment of MAS has had mixed success.
- Early puberty can be treated with various hormonal agents, but results have been inconsistent.
- A class of medications, called bisphosphonates, have recently been used to reduce fracture rates and bone pain in patients with MAS. However, results have again been inconsistent.
- Other endocrine problems require specific medication or surgery.
Complications
- Bony changes in the skull can result in damage to nerves causing vision and/or hearing loss.
- Bony changes in the chest wall may lead to difficulty breathing.
- A type of bone cancer called osteosarcoma develops in up to 2% of patients with MAS. This tumour is found most often in patients who have received radiation treatment to affected bone lesions.
- Although 2 long-term studies have shown no increased risk of premature death, several authors have noted unexplained sudden death in patients with severe features of the disease.
Related information
References:
- McCune-Albright Syndrome – eMedicine dermatology, pediatric diseases
- Albright Syndrome – eMedicine pediatrics, general medicine
- McCune-Albright Syndrome – eMedicine endocrinology
- Dumitrescu CE, Collins MT. McCune-Albright syndrome. Orphanet J Rare Dis. 2008; 3: 12.
- Roth JG, Esterly NB. McCune-Albright syndrome with multiple bilateral café au lait spots. Pediatr Dermatol. 1991 Mar;8(1):35-9.
On DermNet NZ:
Other websites:
- McCune-Albright Syndrome – Medline Plus
- McCune-Albright Syndrome – OMIM
- McCune-Albright Syndrome – National Institute of Child Health and Human Development
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