Interferon-γ Receptor Deficiency: Two-gene Profile (IFNGR1, IFNGR2) (Full Gene Sequencing)

CPT: 81479
Updated on 1/24/2018
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Test Details

Test Includes

This test covers all coding nucleotides of genes IFNGR1 and IFNGR2, 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 IFNGR; guide therapy; 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

Mendelian susceptibility to mycobacterial disease (MSMD), or familial atypical mycobacteriosis, is an inherited immune disorder characterized by the inability to clear mycobacterial infections. Interferon-γ receptor deficiency (IFNGRD) is the most common cause of NSMD and has been associated with mutations in the gene IFNGR1 or IFNGR2. Depending on the exact mutation, disease severity can range from a mild form, which is easily treatable with prophylactic antibiotics and interferon-γ therapy, to a severe form, for which stem-cell transplantation is recommended. Mode of inheritance is typically recessive for the more severe forms and can be recessive or dominant for the milder forms. Genetic testing can confirm a clinical diagnosis of IFGRD, 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; use of 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

Dorman SE, Picard C, Lammas D, et al. Clinical features of dominant and recessive interferon gamma receptor 1 deficiencies. Lancet. 2004 Dec 11-17; 364(9451):2113-2121. 15589309
Remus N, Reichenbach J, Picard C, et al. Impaired interferon gamma-mediated immunity and susceptibility to mycobacterial infection in childhood. Pediatr Res. 2001 Jul; 50(1):8-13. 11420412
Rosenzweig SD, Holland SM. Defects in the interferon-gamma and interleukin-12 pathways. Immunol Rev. 2005 Feb; 203:38-47. 15661020

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