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Test Name:
Interleukin 28 B (IL28B)-Associated Variants, 2 SNPs

  • TMF No:
  • Performance Lab Name:
    ARUP Laboratories
  • Test Mnemonic:
  • ABN:
    Local Coverage Determination (LCD): MolDX: Molecular Diagnostic Tests (MDT) (L36807)
  • CPT Code:
    81400; 81479
  • Ref Lab Test No:
  • Also Known As:
    IL-28B Genotype; IL28B.12979860; Interleukin 28B Polymorphism; Lambda Interferon Genotyping; Ribavirin Genotyping
  • Spec Type:
    Whole blood
  • Spec Container:
    Lavender top (EDTA), Pink top (K2EDTA), or Yellow top (ACD) tube
  • Pref Vol:
    3 mL
  • Min Vol:
    1 mL
  • Patient Prep:
    NOTICE: Genetic tests are often subject to limited coverage and/or prior-authorization requirements. Consult the patient’s medical insurance provider before ordering this test.
    Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
  • Spec Collect:
    Normal phlebotomy procedure. Mix by inverting tube 8 times.
  • Spec Process:
    Transport whole blood in the original collection tube.
  • Spec Store Transport:
  • Spec Stability:
    Room temperature: 72 hours
    Refrigerated: 1 week
    Frozen: Unacceptable
  • Methodology:
    Polymerase Chain Reaction; Single Nucleotide Extension
  • Use:
    Predict response to peginterferon (PEG-IFNa) and ribavirin (RBV) therapy for chronic hepatitis C virus genotype 1 (HCV-1) infection.
  • Interpretive Data:

    Background Information for Interleukin 28 B (IL28B)Associated Variants, 2 SNPs:
    Hepatitis C is an infectious disease that can result in cirrhosis, liver failure, and hepatocellular carcinoma in chronically infected individuals. Hepatitis C virus (HCV) is categorized into six genotypes; HCV genotype 1 (HCV-1) accounts for 75 percent of U.S. cases. Therapy for chronic infection consists of a combination of peginterferon (PEG IFN alpha) and ribavirin (RBV), which is effective in eliminating HCV-1 in 40 to 50 percent of individuals. Single nucleotide polymorphisms (SNPs) rs12979860 C/T and rs8099917 T/G located upstream of the IL28B gene (encoding for lambda or type III interferons), have been associated with both spontaneous clearance and response to PEG-IFN alpha/RBV therapy in individuals infected with HCV-1. For SNP rs12979860, the CC genotype is associated with a two-to threefold greater rate of sustained virological response (SVR) following PEG-IFN alpha/RBV therapy, while the TC and TT genotypes are less likely to respond to treatment. For SNP rs8099917, the TT genotype is associated with a higher rate of SVR after PEG-IFN alpha/RBV therapy, while the GT and GG genotypes are less likely to respond to treatment and achieve SVR.
    Prevalence: 4.1 million Americans (1.6 percent of the U.S. population) have anti-HCV antibodies.
    Allele Frequency: SNP rs12979860 favorable C allele: East Asian 0.90, Caucasian 0.75, Hispanic 0.70, and African American 0.50. SNP rs8099917 favorable T allele: Caucasian 0.75, Asian 0.88, and unknown in other ethnicities.
    Variants Tested: SNP rs12979860 C/T and SNP rs8099917 T/G.
    Clinical Sensitivity: Unknown.
    Methodology: Polymerase Chain Reaction/High Resolution Melt Analysis.
    Analytical Sensitivity & Specificity: 99 percent.
    Limitations: SNPs other than those targeted will not be detected. Mutations in other genes and non-genetic factors that may affect response to hepatitis C therapy are not detected. For HCV genotypes other than type 1, the usefulness of these SNPs for predicting response to therapy is unknown. Diagnostic errors can occur due to rare sequence variations.

    See Compliance Statement C:
    Statement C: The performance characteristics of this test were validated by ARUP Laboratories. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test; however, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. ARUP is authorized under Clinical Laboratory Improvement Amendments (CLIA) and by all states to perform high-complexity testing.
    Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

  • Additional Test Info:
    Additional Technical Information
    Supplemental Resources
  • Day Run:
    Sun, Tue, Thu
  • Time Reported:
    8-11 days
  • Test Type: