Acceptable diagnostic and predictive test for Legius syndrome for symptomatic individuals who test negative for NF1 gene variants.
- 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: Cafe au lait spots, axillary and inguinal freckling, learning disability and macrocephaly. Neurofibromas, lisch
nodules and CNS tumors are not observed.
Incidence: Unknown; may represent 0.5 percent of neurofibromatosis type 1 diagnoses or 8 percent of those with isolated cafe au lait spots.
Inheritance: Autosomal dominant.
Cause: Pathogenic SPRED1 gene mutations
Clinical Sensitivity: Unknown.
Methodology: Bidirectional sequencing of the entire SPRED1 coding region and intron-exon boundaries.
Analytical Sensitivity and Specificity: 99 percent.
Limitations: Some SPRED1 gene regulatory region mutations, deep intronic mutations, and large deletions/duplications will not be detected. Diagnostic errors can occur due to rare sequence variations.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|2002946||Legius Syndrome Specimen|
|2002947||Legius Syndrome Sequencing Interp|
- NF1-Like Syndrome Sequencing and (NF1) Sequencing Exon 22 (Exon 17))
- SPRED1 sequencing
- SPRED1 Sequencing and (NF1) Sequencing Exon 22 (Exon 17))