McCune-Albright syndrome (MAS) is caused by somatic mutations in the GNASgene. This gene provides instructions for making part of a protein that influences many cell functions by regulating hormone activity. GNASmutations that cause MAS result in a protein that causes the enzyme adenylate cyclase to always be "on". This leads to over-production of several hormones, resulting in the signs and symptoms of MAS.
Last updated: 9/9/2016
Is McCune-Albright syndrome inherited?
McCune-Albright syndrome (MAS) is not inherited. It is caused by a random, somatic mutation in the GNAS gene. Mutations that cause MAS occur very early in development, after an egg is fertilized (conception). These mutations are not present in the egg or sperm of the parents of affected children. Because these mutations are acquired after conception, some of the body's cells have a normal GNAS gene, while other cells have the mutated gene. This phenomenon is called mosaicism.
Because mutations that cause MAS are acquired, a person with MAS does not pass the disorder on to children.
Last updated: 9/9/2016
Can McCune-Albright syndrome be found through amniocentesis?
An amniocentesis is a test during pregnancy that removes a small amount of fluid from the sac around the baby (called the amniotic sac) to look for birth defects and chromosome problems. This test usually looks for chromosome problems in the baby including Down syndrome, Trisomy 13, and Trisomy 18. This test also looks for neural tube defects in the fetus such as spina bifida.
An amniocentesis can only be used to diagnose other genetic conditions during pregnancy if a fetus is suspected to have a particular genetic condition, usually based on abnormal ultrasound or family history. Because McCune-Albright syndrome occurs in people without a family history of the condition, an amniocentesis will not detect it. We recommend that you speak with a genetics professional for additional information about testing for this condition.
GeneTests lists the names of laboratories that are performing genetic testing for McCune-Albright syndrome. To view the contact information for the clinical laboratories, conducting testing click here. Please note: Most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional.
Last updated: 6/6/2011
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