Noonan Syndrome - Tiered Molecular
Testing
Noonan syndrome is characterized by short stature, developmental delay, characteristic facial features, a webbed or broad neck, low-set nipples and chest abnormalities. Heart defects are present in up to 80% of patients and mild mental retardation may be a feature in approximately 1/3 of patients.
Noonan syndrome can be caused by a mutation in one of four known genes. The Molecular Diagnostic Laboratory of the Greenwood Genetic Center is offering a tiered approach to the molecular diagnosis of Noonan syndrome. PTPN11 mutations are responsible for approximately 50% of Noonan syndrome cases. Mutations in SOS1 have been identified in approximately 15-20% of those without a PTPN11 mutation. RAF1 and KRAS are each responsible for approximately 5% of individuals with Noonan syndrome. Patients with Noonan-like syndrome with loose anagen hair have recently been identified as having a S2G mutation in SHOC2.
- Tier 1: PTPN11 - full sequencing
- Tier 2: SOS1 - full sequencing
- Tier 3: RAF1 & KRAS - full sequencing AND SHOC2 - S2G mutation only
These tiers may be ordered separately or can be run simultaneously.
The features of Noonan syndrome are often found to overlap with those of Costello syndrome and cardio-facio-cutaneous (CFC) syndrome. Tiered analyses for each of those conditions is also available from the Greenwood Genetic Center.
Specimen requirements: 5 to 10 ml of peripheral blood collected in an EDTA (lavender top) Vacutainer tube is preferred. The minimal blood needed for reliable DNA isolation is 3 ml. If necessary, ACD solution A Vacutainer tubes (yellow top) may be submitted. Please contact the laboratory for more information.
Transport: Please contact the Molecular Diagnostic Lab Coordinator (1-800-473-9411) for shipping information. The specimen should be kept at room temperature and delivered via overnight shipping. FedEx is preferred. If shipment is delayed by one or two days, the specimen should be refrigerated and shipped at room temperature. Do not freeze the specimen. Samples collected on Friday can be safely designated for Monday delivery.
Analysis standards: Analysis will require up to 6 weeks from sample receipt. The laboratory director and technical staff members independently assess the quality and interpretation of the test. The Greenwood Genetic Center Molecular Diagnostic Laboratory is CLIA certified and actively participates in CAP proficiency surveys.
Reporting of Test Results: Test results with interpretation will be mailed and/or faxed following completion of the test. Verbal reports will be telephoned to the person(s) requesting the test when an abnormal test result occurs. Consultation with the laboratory director and explanations of testing protocols are available upon request.
CPT Codes:
- Tier 1: 83890, 83898 (x5), 83904 (x4), 83909 (x4), 83912
- Tier 2: 83890, 83898 (x11), 83904 (x8), 83909 (x8), 83912
- Tier 3: 83890, 83898 (x5), 83904 (x4), 83909 (x4), 83912
Full Panel (Tiers 1, 2, and 3 run simultaneously): 83890, 83898 (x20), 83904 (x19), 83909 (x19), 83912
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