Table 2. [Noonan Syndrome: Frequency of Select Features]. - GeneReviews®

Feature	% of Persons w/Feature	Comment
Eye anomalies	95%
Short stature	50%-70%	For age, sex, & family background
Hypotonia	Majority	Can contribute to feeding problems, speech articulation issues, & delayed attainment of gross motor milestones
Joint hyperextensibility	Majority
Pectus anomaly	Majority	Characteristic pectus deformity of the chest: pectus carinatum superiorly & pectus excavatum inferiorly
Cryptorchidism in males	60%-80%
Congenital heart disease	50%-80%	25%-71% of affected persons have pulmonary valve stenosis, often w/pulmonary valve dysplasia.
Hearing loss	40%	May be sensorineural, conductive, or mixed
Hypertrophic cardiomyopathy	10%-29%	Half of those w/hypertrophic cardiomyopathy are diagnosed by age 6 mos.
Learning disability	25%	~10%-15% of those w/NS require special education.
Intellectual disability ¹	6%-23%
Renal anomalies	11%	Most commonly dilatation of the renal pelvis
Abnormal bleeding or bruising	Bleeding: 6%-10%; bruising: majority

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Adam MP, Feldman J, Mirzaa GM, et al., editors.

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