Noonan Syndrome

National Organization for Rare Disorders, Inc.

Skip to the navigation

It is possible that the main title of the report Noonan Syndrome is not the name you expected.

Disorder Subdivisions

  • None

General Discussion

Noonan syndrome is a common genetic disorder that is typically evident at birth (congenital). The disorder is characterized by a wide spectrum of symptoms and physical features that vary greatly in range and severity. In many affected individuals, associated abnormalities include a distinctive facial appearance; a broad or webbed neck; a low posterior hairline; a typical chest deformity and short stature. Characteristic abnormalities of the head and facial (craniofacial) area may include widely set eyes (ocular hypertelorism); skin folds that may cover the eyes' inner corners (epicanthal folds); drooping of the upper eyelids (ptosis); a small jaw (micrognathia); a depressed nasal root; a short nose with broad base; and low-set, posteriorly rotated ears (pinnae). Distinctive skeletal malformations are also typically present, such as abnormalities of the breastbone (sternum), curvature of the spine (kyphosis and/or scoliosis), and outward deviation of the elbows (cubitus valgus). Many infants with Noonan syndrome also have heart (cardiac) defects, such as obstruction of proper blood flow from the lower right chamber of the heart to the lungs (pulmonary valvular stenosis) and hypertrophic cardiomyopathy. Additional abnormalities may include malformations of certain blood and lymph vessels, blood clotting and platelet deficiencies, learning difficulties or mild intellectual disability, failure of the testes to descend into the scrotum (cryptorchidism) by the first year of life in affected males, and/or other symptoms and findings.

Noonan syndrome is an autosomal dominant genetic disorder caused by abnormalities (mutations) in four main genes: PTPN11 (50%), SOS1 (13%), RAF1 (3-17%), KRAS (less than 5%), with a handful of individuals having a mutation in NRAS, BRAF or MEK2. Noonan-like disorders are found in association with mutations in SHOC2 and CBL.

Supporting Organizations

American Heart Association

7272 Greenville Avenue
Dallas, TX 75231
Tel: (214)784-7212
Fax: (214)784-1307
Tel: (800)242-8721

Children's Cardiomyopathy Foundation

PO Box 547
Tenafly, NJ 7670
Tel: (866)808-2873
Fax: (201)227-7016

Genetic and Rare Diseases (GARD) Information Center

PO Box 8126
Gaithersburg, MD 20898-8126
Tel: (301)251-4925
Fax: (301)251-4911
Tel: (888)205-2311

Human Growth Foundation

997 Glen Cove Avenue
Suite 5
Glen Head, NY 11545
Tel: (516)671-4041
Fax: (516)671-4055
Tel: (800)451-6434

MAGIC Foundation

6645 W. North Avenue
Oak Park, IL 60302
Tel: (708)383-0808
Fax: (708)383-0899
Tel: (800)362-4423

March of Dimes

1275 Mamaroneck Avenue
White Plains, NY 10605
Tel: (914)997-4488
Fax: (914)997-4763
Email: or
Website: and

NIH/National Heart, Lung and Blood Institute

P.O. Box 30105
Bethesda, MD 20892-0105
Tel: (301)592-8573
Fax: (301)251-1223

Noonan Syndrome Support Group, Inc.

P.O. Box 145
Upperco, MD 21155
Tel: (410)374-5245
Tel: (888)686-2224

RASopathies Network USA

244 Taos Road
Altadena, CA 91001-3953
Tel: (626)676-7694

Restricted Growth Association

PO Box 5137
Yeovil, BA20 9FF
United Kingdom
Tel: 3001111970
Fax: 3001112454

The Arc

1825 K Street NW, Suite 1200
Washington, DC 20006
Tel: (202)534-3700
Fax: (202)534-3731
Tel: (800)433-5255

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders (NORD). For a full-text version of this report, go to and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report.

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

Last Updated:  9/24/2012
Copyright  2012 National Organization for Rare Disorders, Inc.