Noonan syndrome

The Noonan syndrome is the most frequent monogenetic cause of heart defects. Monogenetic means that just a single gene is affected. The occurrence of the Noonan syndrome is given variously between 1:500 and 1:2,500. The gene is on chromosome 21 and contains the genetic information for a protein that is of central importance to numerous metabolic and growth processes. This allows the numerous exogenous and endogenous disorders to be derived. Typical for the Noonan syndrome are short stature, triangular face shape with widely set eyes, drooping of the eyelids and a wide neck. A quarter of patients are mildly intellectually challenged. About 80 per cent of the children have a congenital heart defect, often pulmonary stenosis or hypertrophic cardiomyopathy, which can restrict cardiac functioning.The lower than normal life expectancy of people with Noonan syndrome is directly connected to the extent of the cardiac damage.

Author(s): Dr Stefanie Weismann-Günzler
Reviewed by: Dr Heide Seidel
Last updated: 2009-08-06