Severe Combined Immunodeficiency (SCID): Two-gene Profile (IL2RG, JAK3) (Full Gene Sequencing)

CPT: 81405; 81479
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Test Details

Test Includes

This test covers all coding nucleotides of genes IL2RG and JAK3, plus at least two and typically 20 flanking intronic nucleotides upstream and downstream of each coding exon, covering the conserved donor and acceptor splice sites, as well as typically 20 flanking nucleotides in the 5′ and 3′ UTR.

Use

Confirm a clinical diagnosis of SCID; detect carriers; allow early diagnosis in family members

Limitations

This method does not reliably detect mosaic variants; large deletions; large duplications, inversions, or other rearrangements; or deep intronic variants. It may be affected by allele-dropout, it may not allow determination of the exact numbers of T/A or microsatellite repeats, and it does not allow any conclusion as to whether two heterozygous variants are present on the same or on different chromosome copies.

Results of this test are for investigational purposes only. The performance characteristics of this assay have been determined by LabCorp. The result should not be used as a diagnostic procedure without confirmation of the diagnosis by another medically established diagnostic product or procedure.

Methodology

DNA sequencing

Reference Interval

Normal equals reference sequence or variants that are known or predicted to be benign; abnormal equals all other variants.

Additional Information

Severe combined immunodeficiency (SCID) is a recessively (X-linked or autosomal) inherited immune disorder characterized by severe lymphopenia and lack of adaptive immunity, leading to severe and persistent infections. Left untreated, SCID is typically lethal in infancy or childhood. T-cell lymphopenia is common to all forms of SCID, but may be initially masked by the temporary presence of maternal lymphocytes that have crossed the placenta during gestation. Levels of B cells and of natural killer (NK) cells vary depending on the genetic defect. Mutations in IL2RG or JAK3 cause T-B+NK-SCID with X-linked recessive and autosomal recessive inheritance, respectively, and account for about 53% of SCID overall. Genetic testing can confirm a clinical diagnosis of T-B+NK-SCID overall. Genetic testing can confirm a clinical diagnosis of T-B+NK-SCID, clarify the mode of inheritance, and detect mutation carriers within affected families.

Specimen Requirements

Specimen

Whole blood; DNA is accepted (Call 800-345-4363 for DNA collection information.)

Volume

2 mL

Container

Lavender-top (EDTA) tube

Collection

Samples may be stored for brief periods at 4°C. Ship overnight at room temperature.

Storage Instructions

Maintain specimen at room temperature.

Causes for Rejection

Container broken or leaking; container not labeled or label not legible; improper anticoagulant

Clinical Information

Special Instructions

Test orders must include an attestation that the provider has the patient's informed consent for genetic testing. See sample physician office consent form: Consent for Genetic Testing. In the case of family tests (ie, known mutations), please submit the result report of the first patient tested in the family (the index case), if not performed at a LabCorp facility. Other family members are subsequently tested for the specific mutation found in the first patient tested.

References

Buckley RH. Molecular defects in human severe combined immunodeficiency and approaches to immune reconstitution. Annu Rev Immunol. 2004; 22:625-655.15032591
Fischer A, Le Deist F, Hacein-Bey-Abina S, et al. Severe combined immunodeficiency. A model disease for molecular immunology and therapy. Immunol Rev. 2005; 203:98-109.15661024

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
252496 SCID:IL2RG/JAK3 41103-3 252172 Routing 41103-3

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