This is a second tier test and REQUIRES PERMISSION from ARUP's Genetic Counselor (800-242-2787, x2141) before ordering. Preferred initial test is the sequencing and deletion/duplication test.
- Patient Preparation
- Lavender (EDTA), pink (K2EDTA) or yellow (ACD Solution A or B).
- Specimen Preparation
- Transport 3 mL whole blood. (Min: 1 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Characteristics: Neurofibromatosis type 1 (NF1) demonstrates extreme clinical variability. Features include: cafe au lait macules, axillary or inguinal freckling, dermal fibromas, Lisch nodules (iris hamartomas), optic glioma, specific osseous lesions such as tibial pseudarthrosis or sphenoid dysplasia, learning disabilities (50 percent), scoliosis, vertebral dysplasia, and somatic overgrowth. Large NF1 locus deletions increase the risk for neurofibroma development, cognitive abnormalities and malignant peripheral nerve sheath tumors (MPNST).
Incidence: 1 in 3000.
Inheritance: Autosomal dominant; de novo mutations occur in 50 percent of cases.
Penetrance: 100 percent by adulthood.
Cause: Pathogenic NF1 mutations.
Clinical Sensitivity: Approximately 5 percent of NF1 is caused by large NF1 locus deletions and 2 percent due to intragenic deletions.
Methodology: Multiplex ligation-dependent probe amplification (MLPA) to detect large NF1 locus and intragenic deletions/duplications.
Analytical Sensitivity and Specificity: 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations. Single base pair substitutions, small deletions/duplications, regulatory region mutations, and deep intronic mutations will not be detected. Large deletions/duplications of exons 11and 20 will not be detected. The breakpoints for large deletions/duplications will not be determined.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|2001953||Neurofibromatosis 1 (NF1) DelDup Spec|
|2001954||Neurofibromatosis 1 (NF1) DelDup Interp|
- NF1 Deletion/Duplication
- Von Recklinghausen's Neurofibromatosis (NF1) Deletion/Duplication