Acceptable secondary test if no pathogenic variants are detected with PTPN11 testing.
Polymerase Chain Reaction/Sequencing
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
Transport 3 mL whole blood. (Min: 1 mL)
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Background Information for Noonan Syndrome (SOS1) Sequencing:
Characteristics: Short stature, developmental delay, dysmorphic facial features, congenital heart disease, broad or webbed neck, superior pectus carinatum and inferior pectus excavatum, low set nipples, cryptorchidism, coagulation and lymphatic disorders.
Incidence: 1 in 1,000 to 1 in 2,500.
Inheritance: Autosomal dominant.
Cause of NS: Pathogenic mutations in PTPN11, SOS1, RAF1, KRAS and other unidentified genes.
Gene tested: SOS1.
Clinical Sensitivity: Approximately 10 percent of NS is due to SOS1 mutations.
Methodology: Bidirectional sequencing of the entire SOS1 coding region and intron-exon boundaries.
Analytical Sensitivity and Specificity: 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations. Regulatory region mutations, deep intronic mutations and large deletions/duplications will not be detected. Mutations in genes, other than SOS1, will not be evaluated.
Laboratory Developed Test (LDT)
|Component Test Code*||Component Chart Name||LOINC|
|2004196||SOS1 FGS Specimen|
|2004197||Noonan Syndrome (SOS1) Seq Interp|
- SOS1 sequencing assay