Ordering Recommendation

Preferred test to confirm Legius syndrome for symptomatic individuals who test negative for NF1 gene variants.

Mnemonic
LS FGA
Methodology

Polymerase Chain Reaction/Sequencing/Multiplex Ligation-dependent Probe Amplification

Performed

Varies

Reported

28-35 days

New York DOH Approval Status
Specimens from New York clients will be sent out to a New York DOH approved laboratory, if possible.
Specimen Required
Patient Preparation
Collect

Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).

Specimen Preparation

Transport 3 mL whole blood. (Min: 2 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions
Remarks
Stability

Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable

Reference Interval

By report

Interpretive Data

Background Information for Legius Syndrome (SPRED1) Sequencing and Deletion/Duplication:
Characteristics: Cafe au lait spots, axillary and inguinal freckling, learning disabilities 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 and multiplex ligation-dependent probe amplification (MLPA) of the entire coding region and intron-exon boundaries of the SPRED1 gene.
Analytical Sensitivity and Specificity:
99 percent.
Limitations
: Diagnostic errors can occur due to rare sequence variations. Regulatory region mutations and deep intronic mutations will not be detected. Deletion/duplication breakpoints will not be determined.

Compliance Category

Laboratory Developed Test (LDT)

Note
Hotline History
N/A
CPT Codes

81405; 81479

Components
Component Test Code* Component Chart Name LOINC
2008348 Legius Syndrome (SPRED1)Seq, DelDup Spcm
2008349 Legius Syndrome (SPRED1)Seq, DelDup Int
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • SPRED1 sequencing and deletion/duplication
Legius Syndrome (SPRED1) Sequencing and Deletion/Duplication