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Laboratory Test Directory

Interleukin 28B Associated Variants, IL28B, 2 SNPs

Components

Name Method Department Units
IL28B Assoc Variants 2SNP Polymerase Chain Reaction/Single Nucleotide Extension
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IL28B-Assoc Variants, 2 SNPs Specimen; IL28B rs12979860; IL28B rs8099917; IL28B-Assoc Variants, 2SNPs Interp

Specimen Requirements

Whole blood

Container Type Container Size Specimen Volume
Preferred

Purple tube (EDTA)

3 mL 3 mL
Alternate

Yellow tube (ACD-A)

8 mL 3 mL
Alternate

Yellow tube (ACD-B)

8 mL 3 mL
Stability

Room temperature - 3 day(s)
Refrigerated - 1 week(s)

Specimen Preparation

  • Transport to laboratory as soon as possible
  • Do not centrifuge

Reasons for Rejection

  • Frozen specimen

Comments

This test detects genetic variants associated with interleukin 28 B (IL28B) that may aid in predicting probability of treatment response. Characteristics: 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: PCR and fluorescence monitoring. 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.

CPT Code

  • 81400
  • 81479