Ordering Recommendation

Predict response to peginterferon (PEG-IFNα)/ribavirin (RBV) therapy for chronic hepatitis C virus genotype 1 (HCV-1) infection.

Mnemonic
IL28B
Methodology

Polymerase Chain Reaction/Single Nucleotide Extension

Performed

Sun, Tue, Thu

Reported

7-10 days

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
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.

Unacceptable Conditions
Remarks
Stability

Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable

Reference Interval

By report

Interpretive Data

Background Information for Interleukin 28B-Associated Variants, IL28B, 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:
Polymerase chain reaction followed by single nucleotide extension (SNE) and capillary electrophoresis.
Analytical Sensitivity and 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.

Compliance Statement C: For human genetic inheritable conditions and mutations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Note
Hotline History
N/A
CPT Codes

81283; 81479

Components
Component Test Code* Component Chart Name LOINC
2004681 IL28B-Assoc Variants, 2 SNPs Specimen 31208-2
2004682 IL28B rs12979860 60279-7
2004683 IL28B rs8099917
2012617 IL28B-Assoc Variants, 2 SNPs Interp
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • Hepatitis C Virus Genotyping
  • IL28B.12979860
  • Interleukin 28B Polymorphism
  • Lambda Interferon Genotyping
  • Ribavirin Genotyping
Interleukin 28 B (IL28B)-Associated Variants, 2 SNPs