Noonan syndrome

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Description from OMIM

Noonan syndrome (NS) is an autosomal dominant disorder characterized by short stature, facial dysmorphism, and a wide spectrum of congenital heart defects. The distinctive facial features consist of a broad forehead, hypertelorism, downslanting palpebral fissures, a high-arched palate, and low-set, posteriorly rotated ears. Cardiac involvement is present in up to 90% of patients. Pulmonic stenosis and hypertrophic cardiomyopathy are the most common forms of cardiac disease, but a variety of other lesions are also observed. Additional relatively frequent features include multiple skeletal defects (chest and spine deformities), webbed neck, mental retardation, cryptorchidism, and bleeding diathesis (summary by Tartaglia et al., 2002). Genetic Heterogeneity of Noonan Syndrome See also NS3 (609942), caused by mutation in the KRAS gene (190070); NS4 (610733), caused by mutation in the SOS1 gene (182530); NS5 (611553), caused by mutation in the RAF1 gene (164760); NS6 (613224), caused by mutation in the NRAS gene (164790); NS7 (613706), caused by mutation in the BRAF gene (164757); NS8 (615355), caused by mutation in the RIT1 gene (609591); NS9 (616559), caused by mutation in the SOS2 gene (601247); and NS10 (616564), caused by mutation in the LZTR1 gene (600574). See also NS2 (605275) for a possible autosomal recessive form of NS; Noonan syndrome-like disorder with loose anagen hair-1 (NSLH1; 607721), caused by mutation in the SHOC2 gene (602775); Noonan syndrome-like disorder with loose anagen hair-2 (NSLH2; 617506), caused by mutation in the PPP1CB gene (600590); and Noonan syndrome-like disorder with or without juvenile myelomonocytic leukemia (NSLL; 613563), caused by mutation in the CBL gene (165360). Mutations in the neurofibromin gene (NF1; 613113), which is the site of mutations causing classic neurofibromatosis type I (NF1; 162200), have been found in neurofibromatosis-Noonan syndrome (NFNS; 601321).

Prevalence of clinical parameters (%)

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List of symptoms

Symptom/sign Organ system Percent affected Pubmed id Added on(yyyy-mm-dd) Edit/add reference
Hypertelorism nervous 74 % 1446772 2013-07-10
Bruising integumentary 70 % 16990350 2013-07-10
Pulmonary stenosis circulatory 66 % 23750712 2013-07-10
Pulmonary stenosis circulatory 65 % 16990350 2013-07-10
Myopia nervous 53 % 16990350 2013-07-10
Ptosis nervous 48 % 1446772 2013-07-10
Strabismus nervous 48 % 1446772 2013-07-10
Prominent corneal nerves nervous 46 % 1446772 2013-07-10
Epicanthal fold integumentary 39 % 1446772 2013-07-10
Downward sloping palpebral apertures nervous 38 % 1446772 2013-07-10
Amblyopia nervous 33 % 1446772 2013-07-10
Cardiomyopathy circulatory 19 % 16990350 2013-07-10
Hypertrophic cardiomyopathy circulatory 19 % 16990350 2013-07-10
Dental caries digestive 15 % 16990350 2013-07-10
Cardiomyopathy circulatory 14 % 23750712 2013-07-10
Hypertrophic cardiomyopathy circulatory 14 % 23750712 2013-07-10
Hypermetropia nervous 14 % 16990350 2013-07-10
Scoliosis skeletal 13 % 16990350 2013-07-10
Seizures nervous 13 % 16990350 2013-07-10
Nystagmus nervous 9 % 1446772 2013-07-10
Cataract nervous 8 % 1446772 2013-07-10
Conductive hearing loss nervous 4 % 16990350 2013-07-10
Anterior stromal dystrophy nervous 4 % 1446772 2013-07-10
Hearing loss nervous 3 % 16990350 2013-07-10
Panuveitis nervous 2 % 1446772 2013-07-10

List of references:

Ocular manifestations of Noonan syndrome.
N B Lee, L Kelly, M Sharland,

Noonan syndrome is a genetic condition inherited in an autosomally dominant manner, characterised by congenital heart disease, short stature, abnormal facies and the somatic features of Turner's syndrome, but a normal Karyotype. The ophthalmological and orthoptic findings on 58 patients with Noonan syndrome are reported. External features were hypertelorism (74%), downward sloping palpebral apertures (38%), epicanthic folds (39%) and ptosis (48%). The orthoptic examination revealed strabismus in 48%, refractive errors in 61%, amblyopia in 33%, and nystagmus in 9% of cases. Sixty-three per cent of cases had anterior segment changes consisting of: Prominent corneal nerves (46%), anterior stromal dystrophy (4%), cataracts (8%) and panuveitis (2%). Fundal changes occurred in 20% of the study group, including optic nerve head drusen, optic disc hypoplasia, colobomas and myelinated nerves. Forty-seven per cent required non surgical treatment and a further 16% had undergone surgery for strabismus or ptosis. Only three patients had no visual defects. With such a high incidence of ophthalmic abnormalities it is clearly important that children with Noonan syndrome are screened by an ophthalmologist at an early age.

Eye (London, England) - 1992

The natural history of Noonan syndrome: a long-term follow-up study.
A C Shaw, K Kalidas, A H Crosby, S Jeffery, M A Patton,

To define better the adult phenotype and natural history of Noonan syndrome.

Archives of disease in childhood - Feb 2007

Cardiac findings in Noonan syndrome on long-term follow-up.
John L Colquitt, Jacqueline A Noonan,

Noonan syndrome (NS) is the second most common genetic syndrome associated with cardiac abnormalities, including, most notably, pulmonary stenosis (PS) and hypertrophic cardiomyopathy (HCM). Little is known about the natural history of heart disease in this unique subset of patients. We sought to contribute information on the natural history of NS by looking at how the cardiac disease progresses with time.

Congenital heart disease -