CausesBy Mayo Clinic staff
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|Autosomal dominant inheritance pattern|
The cause of Noonan syndrome is a mutation in a particular gene. Currently, scientists know of seven genes that can cause Noonan syndrome. The mutation can be inherited from a parent who carries the defective gene (autosomal dominant), or it can develop because of a new mutation in children who don't have a genetic predisposition for the disease. Children who have one parent with Noonan syndrome have a 50 percent chance of developing the disorder.
Defects in these seven genes cause them to produce proteins that are continually active. Because these genes play a role in the formation of many tissues throughout the body, this constant activation of their proteins disrupts the normal process of cell growth and division.
In some people, none of the seven genes has a mutation, which may mean that some other, still undiscovered genes cause Noonan syndrome.
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