Noonan Spectrum Disorders Panel (18)
Related Genes: BRAF, CBL, HRAS, KRAS, LZTR1, MAP2K1, MAP2K2, NF1, NRAS, PPP1CB, PTPN11, RAF1, RASA2, RIT1, SHOC2, SOS1, SOS2, and SPRED1.
Noonan Spectrum Disorders are part of a group of genetically heterogeneous developmental syndromes known as RASopathies that are caused by heterozygous germline variants in genes involved in the Ras/MAPK signaling pathway. This pathway is essential for regulation of the cell cycle, cell differentiation, and cellular growth. The most common RASopathy is Noonan Syndrome, which occurs in 1 in 1,000 to 1 in 2,500 live births. It generally presents with short stature, variable cardiac abnormalities – most commonly pulmonic stenosis and hypertrophic cardiomyopathy, facial dysmorphisms including a broad forehead, hypertelorism with down-slanting palpebral fissures, a high-arched palate, and low-set, posteriorly rotated ears, as well as varying degrees of developmental delay and intellectual disability. Other syndromes included in this panel, such as Costello syndrome, Cardiofaciocutaneous syndrome, Neurofibromatosis-Noonan syndrome, and Legius syndrome, often display considerable symptom overlap with additional identifying characteristics.
The disorders included in this panel are typically inherited in an autosomal dominant (AD) manner, but de novo occurrence is common and rare families with autosomal recessive inheritance have been reported for some genes on this panel. Most pathogenic variants are fully penetrant (meaning that all individuals with a variant will develop disease) although differences with regard to clinical features, age at onset or severity are common (variable expressivity).
Clinical Utility: Genetic testing of an individual may be indicated to distinguish hereditary disorder from acquired (non-genetic) causes, provide information on the likelihood of related health issues, guide clinical management, and establish disease risk to other family members and future generations.
Methods: The Comprehensive Arrhythmias Panel and subpanels offered by Sema4 primarily utilizes next-generation sequencing (NGS) to identify variants within the genes analyzed. Copy number variant (CNV) detection by NGS is also utilized to increase diagnostic yield. Supplemental and confirmatory technology used in this panel may include targeted genotyping, multiplex ligation-dependent probe amplification (MLPA), exon array, quantitative PCR, and Sanger sequencing. Ultra high-resolution medical exon array (UHRMEA) is available for deletion/duplication studies of gene(s) within this panel as either reflex (add-on), concurrent, or standalone test. UHRMEA provides single exon level coverage for the majority of the exons within this panel. Variant classification and interpretation are performed based on the American College of Medical Genetics Standards and guidelines for the interpretation of sequence variants.
Targeted Testing: Targeted familial mutation analysis or single gene testing is available for any of the genes on this panel. Prenatal diagnosis is also available for known familial variants; please contact our laboratory at 800-298-6470 to discuss prior to sending any prenatal samples.
STAT prenatal testing for this panel can be performed for fetuses that present with certain ultrasound findings (cystic hygroma, increased nuchal translucency, etc.) after a normal chromosome analysis.
Postnatal blood samples:
2 yellow-top (ACD-A or ACD-B) or 2 lavender-top (EDTA) tubes, 5-10 mL of blood from the patient are required. One blood tube from both parents is requested.
1 yellow-top (ACD-A or ACD-B) or 1 lavender-top (EDTA) tube, 2 mL of blood from the patient are required. Additionally, 1 yellow-top (ACD-A or ACD-B) or 1 lavender-top (EDTA) 5-10 mL tube of blood from both parents is requested.
Please inquire with lab (800-298-6470 option 2)
Prenatal testing for a known familial variant:
- Two confluent T-25 flasks of cultured cells from amniotic fluid or chorionic villi
- >4 mg of direct chorionic villi tissue
- 15 mL of direct amniotic fluid
- 5-10 mL of blood in an EDTA tube (lavender top) is required from each biological parent. Parental blood samples may be used for maternal cell contamination studies or confirmation studies.
- Send in previous report of known familial variant with specimen
- A minimum of 10 μL DNA (50-250 ng/μL) is required for testing. 20 μL DNA (50-350 ng/μL) is recommended
- Saliva specimens are accepted upon request. Please contact our laboratory to obtain saliva kits
- Saliva samples should be collected in Oragene DNA (OG-500) kits by DNA Genotek
- 1 cheek swab specimen collected from ORAGENE kit from the patient is required. 1 cheek swab specimen collected from ORAGENE kit from both parents is requested.
Samples should be kept and shipped refrigerated or at room temperature. Do not freeze specimens.
Include the following with each sample:
- Completed and signed test requisition form and informed consent
- Billing information or payment (include copy of insurance card)
- Contact information for referring physician
- Testing to be performed
- Indication for testing, patient’s family history, ethnic background and prior relevant test results
Send same day or overnight (check for morning delivery) to:
62 Southfield Ave
Stamford, CT 06902
Results are reported in 10-14 business days (for prenatal samples performed on direct specimen) and in 3-4 weeks (for postnatal samples) from the receipt of the specimen.