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.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

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 (INACTIVE as of 08/16/21: Refer to 3003927 in the August Hotline)