Health Dictionary
Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.
Noonan syndrome other diagnostic studies
Introduction
Overview
Overview
Although not always required, genetic testing can confirm the diagnosis but not exclude it. Classically PTPN11 mutations can be seen in approximately half of the patients.
Other Diagnostic Studies
Other Diagnostic Studies
Genetic Analysis
Eight genes all involved in the RAS/MAP kinase pathway have been identified as possible causes for Noonan syndrome. In order of prevalence, the causative mutations involve the following genes: PTPN11, SOS1, RAF1, SHOC2, KRAS, BRAF, NRAS, and CBL. Definitive diagnosis is usually with genetic testing which is commonly by chip-based sequencing, to test all the genes that could be involved simultaneously. [1] If chip based-testing is not available, PTPN11 sequencing should be performed first. If PTPN11 is negative considering other genes can be based on the clinical findings detailed below:[2]
- SOS1: Absent developmental delays, normal stature, skin and hair findings
- RAF1: Hypertrophic cardiomyopathy
- KRAS: Significant developmental delay and cognitive impairment
- SHOC2: Thin, slow-growing, sparse hair
Not all patients require genetic testing as the diagnosis is mostly clinical. A positive genetic test can confirm the diagnosis, but a negative test cannot exclude it.[2]
References
References
- ↑ Roberts AE, Allanson JE, Tartaglia M, Gelb BD (2013). “Noonan syndrome”. Lancet. 381 (9863): 333–42. doi:10.1016/S0140-6736(12)61023-X. PMID 23312968.
- ↑ 2.0 2.1 Romano AA, Allanson JE, Dahlgren J, Gelb BD, Hall B, Pierpont ME; et al. (2010). “Noonan syndrome: clinical features, diagnosis, and management guidelines”. Pediatrics. 126 (4): 746–59. doi:10.1542/peds.2009-3207. PMID 20876176.
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Serge Korjian, Yazan Daaboul