ARUP's Laboratory Test Directory

Interleukin 28 B (IL28B)-Associated Variants, 2 SNPs : 2004680
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Additional Technical Information
  


Mnemonic: IL28B

Ordering Recommendation: Detects genetic variants associated with interleukin 28 B (IL28B) that may aid in predicting probability of treatment response.
Methodology: Qualitative Polymerase Chain Reaction/Qualitative Fluorescence Monitoring
Performed: Mon, Thu
Reported: 7-10 days
Specimen Required: Collect: Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).

Specimen Preparation: Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature: Refrigerated.

Stability (collection to initiation of testing): Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Reference Interval:
By report
Interpretive Data: Background Information for Interleukin 28 B (IL28B) Associated Variants, 2 SNPs:
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. Rare diagnostic errors may occur due to primer site mutations.

This test is performed pursuant to an agreement with Roche Molecular Systems, Inc.



Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.

See Compliance Statement C: www.aruplab.com/CS
CPT Code(s): 81479
Cross References: Hepatitis C Virus Genotyping (Interleukin 28 B (IL28B)-Associated Variants, 2 SNPs) , IL-28B (Interleukin 28 B (IL28B)-Associated Variants, 2 SNPs) , IL28B.12979860 (Interleukin 28 B (IL28B)-Associated Variants, 2 SNPs) , Interleukin 28B Polymorphism (Interleukin 28 B (IL28B)-Associated Variants, 2 SNPs) , Lambda Interferon Genotyping (Interleukin 28 B (IL28B)-Associated Variants, 2 SNPs) , Ribavirin Genotyping (Interleukin 28 B (IL28B)-Associated Variants, 2 SNPs)