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Noonan Syndrome

What is Noonan syndrome?

Noonan syndrome is a genetic disorder typically marked by short stature, a characteristic facial appearance that includes widely spaced eyes, flattened bridge of the nose, and droopy eyelids, and often a heart condition. It can affect mental and physical development. Mild mental retardation occurs in about 35% of cases.

What causes Noonan syndrome?

The exact cause of the disorder is unknown. It is thought to occur in about 1 in 1,000 people, though there is no single test to diagnose it. Milder cases may go unnoticed, particularly if there is no obvious heart disease. The chance of passing on this disorder to offspring, which is thought to occur only through the mother, is estimated to be about 50%.

What heart conditions may be associated with Noonan syndrome?

About 80% of cases involve a heart defect, usually pulmonary stenosis, hypertrophic cardiomyopathy, atrial septal defect, or ventricular septal defect.

What is the long-term outlook for children with Noonan syndrome?

Many children with Noonan syndrome go on to lead normal lives, depending on the extent and severity of features of the disease in a given individual, like heart conditions, which may require surgery. Social difficulties may be an issue, if physical abnormalities are prominent.

For more information about Noonan syndrome, please ask to be referred to a genetic counsellor.

Fraser Golding, MD, FRCPC

12/14/2009




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