Table 2.

Diagnostic Criteria for Noonan Syndrome

Feature	A = Major	B = Minor
1. Facial	Typical facial dysmorphology (facial  features vary with age and are  described in Figures 1 through 4)	Suggestive facial  dysmorphology
2. Cardiac	Pulmonary valve stenosis,  hypertrophic cardiomyopathy,  and/or electrocardiographic results  typical of Noonan syndrome	Other defect
3. Height	< 3rd percentile	< 10th percentile
4. Chest wall	Pectus carinatum/excavatum	Broad thorax
5. Family  history	First-degree relative with definite  Noonan syndrome	First-degree relative  with suggestive  Noonan syndrome
6. Other  features	All of the following: intellectual  disability, cryptorchidism, and  lymphatic vessel dysplasia	One of the following:  intellectual disability,  cryptorchidism, or  lymphatic vessel  dysplasia

note: Noonan syndrome is considered present if the patient has typical facial dysmorphology plus one feature from categories 2A through 6A or two categories from features 2B through 6B, or has suggestive facial dysmorphology plus two features from categories 2A through 6A or three features from categories 2B through 6B.

Adapted with permission from van der Burgt I, Berends E, Lommen E, van Beersum S, Hamel B, Mariman E. Clinical and molecular studies in a large Dutch family with Noonan syndrome. Am J Med Genet. 1994;53(2):190.