IL28B Gene Analysis Common Variants
Label Mnemonic: IL28B
Epic Lab Code: LAB7510
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
Whole Blood
Collection Medium:
Pink top tube 6 mL (K2-EDTA)
Minimum:
Preferred Minimum: 3 mL whole blood in pink (EDTA) top tube
Absolute Minimum: 1 mL whole blood in pink (EDTA) top tube
Turn Around Time:
7-10 days upon receipt at reference laboratory
Reference Range:
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.
Comments:
Please print, complete and submit the following form to the lab, with the specimen and the A-1a Miscellaneous Request: Informed Consent For Molecular Genetic Testing from ARUP Laboratories.
Methodology:
Polymerase Chain Reaction/High Resolution Melt Analysis
CPT Code:
81400