Jacqueline Noonan, paediatrician and heart specialist in 1963, published a report on a small group of patients with typical facies, congenital heart defect, and some clinical features similar to Turner syndrome, but with normal chromosomes. Its after her that this syndrome has been named.
Noonan syndrome is inherited as an autosomal dominant condition. This means that the Noonan gene is on a non-sex (autosomal) chromosome and is transmitted from parent with a 50% probability to child. Although one dose of the Noonan gene is enough to cause the syndrome. A gene for Noonan syndrome (NS1) has been mapped to chromosome number 12. There are several different Noonan genes.
The frequency of the Noonan syndrome is estimated to be between 1:1,000 and 1:2,500 in the general population
|Main features of this syndrome are:
Other possible heart defects are hypertrophic cardiomyopathy (thickened heart muscle), atrial septum defect (hole in the wall separating the anterior heart chambers), ventricular septum defect(hole in the wall separating the main heart chambers), septal hypertrophy or a combination of all these defects.
|Other Facial features that may be present in this syndrome are:
Variations occur in the facial features and they change with the age. As the child grows, the face gradually becomes more normal, often more triangular with a high forehead.
|Other features of this syndrome