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Noonan syndrome in Child
See also in: External and Internal Eye
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Noonan syndrome in Child

See also in: External and Internal Eye
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Contributors: Harold E. Cross MD, PhD, Lowell A. Goldsmith MD, MPH, Lauren Patty Daskivich MD, MSHS
Other Resources UpToDate PubMed

Synopsis

Noonan syndrome is a clinically and genetically heterogeneous group of heritable conditions with significant physical and functional manifestations. In females, it is easily confused with the Turner syndrome (XO syndrome), but the chromosomes are normal in Noonan syndrome, which is inherited in an autosomal dominant pattern. Physical features include short stature, short neck with pterygium colli (neck webbing), widely spaced eyes (hypertelorism), and a downward slant to the lid fissures. The majority of patients have cardiac anomalies including coarctation of the aorta, hypertrophic cardiomyopathy, septal defects, and pulmonary valve anomalies (stenosis, dysplasia). They may exhibit easy bruising and prolonged bleeding secondary to thrombocytopenia and abnormal platelet function. Cryptorchidism is common in males. Most patients have normal mental function, but some have intellectual disabilities evident as speech and language problems.

For more information, see OMIM.

Codes

ICD10CM:
Q87.1 – Congenital malformation syndromes predominantly associated with short stature

SNOMEDCT:
205824006 – Noonan's syndrome

Look For

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

  • Both Turner syndrome (XO karyotype) in females and "male Turner syndrome" in males superficially have some similar facial and body characteristics, but the organ anomalies are different.
  • Likewise, the body habitus, pulmonic valve disease, frequent café-au-lait spots, and psychomotor delays found in the Watson syndrome (a subset of neurofibromatosis associated with pulmonic stenosis) can resemble the Noonan syndrome.
  • Café au lait macules are an important feature of neurofibromatosis.
  • LEOPARD syndrome patients may physically resemble those with the Noonan syndrome, especially among younger individuals, but the development of hearing loss in older individuals helps separate LEOPARD syndrome. Adding to the confusion, patients with both syndromes may have similar pigmented skin lesions and the inheritance patterns are the same.

Best Tests

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Therapy

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References

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Last Updated: 10/16/2018
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Noonan syndrome in Child
See also in: External and Internal Eye
Print 14 Images
View all Images (14)
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Noonan syndrome (Facial Features) : Seizures, Eyelid ptosis, Hypertelorism, Hypotonia, Joint hypermobility, Pectus excavatum, Short stature, Strabismus, Webbed neck, PTT prolonged, PLT decreased
Clinical image of Noonan syndrome
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