eMedicine Specialties > Pediatrics: Genetics and Metabolic Disease > Genetics

Noonan Syndrome: Follow-up

Author: Jennifer Ibrahim, MD, Chief, Genetics Division, St Joseph's Children's Hospital
Coauthor(s): Margaret M McGovern, MD, PhD, Professor and Chair of Pediatrics, Stony Brook University, New York
Contributor Information and Disclosures

Updated: Jul 24, 2009

Follow-up

Further Outpatient Care

  • All patients with Noonan syndrome require ongoing developmental, audiologic, and ophthalmologic follow-up. Direct other follow-up at specific findings (eg, hematology follow-up for patients with bleeding disorders).

Deterrence/Prevention

  • If a causative mutation is found in patients, parental studies should be offered in order to distinguish familial cases from sporadic cases. If an individual carries a germline mutation, prenatal diagnosis can be offered in future pregnancies. The presentation can vary widely within families.
  • Prenatal testing for Noonan syndrome can be considered in the absence of a family history when cystic hygroma is seen on ultrasonography and karyotyping of amniocytes is normal.

Patient Education

  • Once the pattern of inheritance has been identified, parents need to be counseled regarding recurrence risk with each pregnancy. Sporadic cases present minimal recurrence risk to the siblings of the affected child; the exception is parental gonadal mosaicism. Offspring of an affected individual have a 50% chance of developing Noonan syndrome.
  • Patients with bleeding disorders must be advised against the use of aspirin and aspirin-containing products or other medications that may interfere with coagulation or platelet function.

Miscellaneous

Medicolegal Pitfalls

  • Recurrence risk for parents who do not appear to be affected or who have only some facial features of Noonan syndrome is 5%. Gonadal mosaicism may account for this increase over population risk. Affected individuals have a 50% chance of passing on the disorder with each pregnancy.

Special Concerns

  • Before any patient with Noonan syndrome can undergo a surgical procedure, a full hematologic workup must be performed.
  • Female patients have normal pubertal development and fertility. Fertility in males with undescended testes may be decreased. For this reason, the mother is more frequently the transmitting parent in familial cases.
 


More on Noonan Syndrome

Overview: Noonan Syndrome
Differential Diagnoses & Workup: Noonan Syndrome
Treatment & Medication: Noonan Syndrome
Follow-up: Noonan Syndrome
Multimedia: Noonan Syndrome
References
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References

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  2. Tartaglia M, Pennacchio LA, Zhao C, et al. Gain-of-function SOS1 mutations cause a distinctive form of Noonan syndrome. Nat Genet. Jan 2007;39(1):75-9. [Medline].

  3. Pandit B, Sarkozy A, Pennacchio LA, et al. Gain-of-function RAF1 mutations cause Noonan and LEOPARD syndromes with hypertrophic cardiomyopathy. Nat Genet. Aug 2007;39(8):1007-12. [Medline].

  4. Schubbert S, Zenker M, Rowe SL, et al. Germline KRAS mutations cause Noonan syndrome. Nat Genet. Mar 2006;38(3):331-6. [Medline].

  5. Carta C, Pantaleoni F, Bocchinfuso G, et al. Germline missense mutations affecting KRAS Isoform B are associated with a severe Noonan syndrome phenotype. Am J Hum Genet. Jul 2006;79(1):129-35. [Medline].

  6. Pierpont EI, Pierpont ME, Mendelsohn NJ, Roberts AE, Tworog-Dube E, Seidenberg MS. Genotype differences in cognitive functioning in Noonan syndrome. Genes Brain Behav. Apr 2009;8(3):275-82. [Medline].

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Further Reading

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Keywords

Noonan syndrome, Noonan's syndrome, hypertelorism, down-slanting eyes, webbed neck, congenital heart disease, congenital heart disease, short stature, chest deformity, polyhydramnios, fetal edema, cystic hygroma, ptosis, strabismus, amblyopia, high nasal bridge, pectus carinatum, pectus excavatum, scoliosis, hepatosplenomegaly, talipes equinovarus, radioulnar synostosis, cervical spine fusion, lymphedema, LEOPARD syndrome, bleeding diatheses, treatment, diagnosis

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Contributor Information and Disclosures

Author

Jennifer Ibrahim, MD, Chief, Genetics Division, St Joseph's Children's Hospital
Jennifer Ibrahim, MD is a member of the following medical societies: American Society of Human Genetics
Disclosure: Nothing to disclose.

Coauthor(s)

Margaret M McGovern, MD, PhD, Professor and Chair of Pediatrics, Stony Brook University, New York
Margaret M McGovern, MD, PhD is a member of the following medical societies: American Academy of Pediatrics and American Society of Human Genetics
Disclosure: Genzyme Grant/research funds PI

Medical Editor

Elaine H Zackai, MD, Professor of Pediatrics, Professor of Obstetrics and Gynecology, Professor of Pediatrics in Human Genetics, University of Pennsylvania School of Medicine; Director, Clinical Genetics Center, University of Pennsylvania; Senior Physician and Director of Clinical Genetics, The Children's Hospital of Philadelphia
Elaine H Zackai, MD is a member of the following medical societies: American Cleft Palate/Craniofacial Association, American College of Medical Genetics, and American Society of Human Genetics
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from financial planner; Avanir Pharma Stock Investment from financial planner ; WebMD Salary and stock Employment and investment from financial planner

Managing Editor

Robert Anthony Saul, MD, Clinical Professor, Department of Pediatrics, University of South Carolina; Senior Clinical Geneticist, Greenwood Genetic Center
Robert Anthony Saul, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Medical Genetics, and American College of Physician Executives
Disclosure: Nothing to disclose.

CME Editor

Daniel Rauch, MD, FAAP, Director, Pediatric Hospitalist Program, Associate Professor, Department of Pediatrics, New York University School of Medicine
Daniel Rauch, MD, FAAP is a member of the following medical societies: Ambulatory Pediatric Association, American Academy of Pediatrics, and Society of Hospital Medicine
Disclosure: Baxter Honoraria Consulting

Chief Editor

Bruce Buehler, MD, Professor, Department of Pediatrics, Pathology and Microbiology, Executive Director, Hattie B Munroe Center for Human Genetics, University of Nebraska Medical Center
Bruce Buehler, MD is a member of the following medical societies: American Academy for Cerebral Palsy and Developmental Medicine, American Academy of Pediatrics, American Association on Mental Retardation, American College of Medical Genetics, American College of Physician Executives, American Medical Association, and Nebraska Medical Association
Disclosure: Nothing to disclose.

 
 
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