X-linked Lymphoproliferative Disease (XLP): SH2D1A (Full Gene Sequencing)

CPT: 81404
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Test Details

Test Includes

This test covers all coding nucleotides of gene SH2D1A, 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 XLP; 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

X-linked lymphoproliferative disease (XLP), also known as Duncan's disease, is an X-linked recessive immune disorder characterized by fulminant infectious mononucleosis (FIM), dysgammaglobulinemia, and/or lymphoproliferative disorders. FIM, which occurs in response to infection with Epstein-Barr virus, affects approximately 60% of XLP patients and is the most severe manifestation, often leading to death within one to two months. Dysgammaglobulinemia affects about 30% of patients, and malignant and nonmalignant lymphomas occur in 20% to 30% of XLP patients. To date, mutations in SH2D1A are the only known cause of XLP. Genetic testing can confirm a clinical diagnosis of XLP 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

In cases in which a known mutation can be documented, the physician may prefer to order test 252740.

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

Sumegi J, Huang D, Lanyi A, et al. Correlation of mutations of the SH2D1A gene and epstein-barr virus infection with clinical phenotype and outcome in X-linked lymphoproliferative disease. Blood. 2000 Nov 1; 96(9):3118-3125.11049992

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
252535 XLP:SH2D1A 41058-9 252158 Routing 41058-9

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The LOINC® codes are copyright © 1994-2017, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf