INTERLEUKIN 28B (IL28B) GENOTYPING
Label Name: IL28B GENOTY
Lab Discipline: Molecular Diagnostics
Institution:  Duke University Health System 
EAP ID:  LAB6599 
Last Review:  3/17/2017 10:14:19 AM
Specimen Type
  Whole Blood (EDTA)
Container & Volume
  Age Group   Container   Volume  
  0  - 18 Years LAVENDER TOP TUBE 2  ML
Label Reminders
  Be sure to include the patient's name, history #, date and time of collection, and collector's initials
Collection Notes
  All:
  • Peripheral Blood: One lavender-top EDTA tube (minimum of 3 mls) is required for testing. Forward unprocessed peripheral blood promptly to the laboratory at ambient temperatures. THE SPECIMEN CANNOT BE FROZEN. GREEN-TOP (HEPARIN) TUBES ARE NOT ACCEPTABLE FOR TESTING.

    Buccal swab: (using the MDL specimen collection kit): Scrape the inside of the mouth using 10 strokes with a sterile nylon bristle cytology brush. Dip the brush up and down 10 times in the provided solution (Cell Lysis Solution) contained in the 1.5mL microfuge tube. Detailed instructions and collection kits are available on request from the Clinical Molecular Diagnostics Laboratory.
 
Transport
  Deliver peripheral blood and buccal swab specimens to laboratory at ambient temperature. If there is a delay of more than 24 hours in delivery, refrigerate the sample. DO NOT FREEZE.

Turn Around Time -  Routine: 7 DAYS   Stat: N/A
Reference Values


IL28B GENOTY



No Reference Values
Methodology
  This assay uses a Taqman allelic discrimination technique to determine the genotype of a single nucleotide polymorphism (SNP: rs12979860 C/T) 3kb upstream of the IL28B gene. Genomic DNA is extracted from the patient sample and a single PCR-based allelic discrimination assay is performed using oligonucleotide primers that flank the polymorphism of interest and fluorescently tagged (FAM and VIC) Taqman MGB-probes that specifically target each of the two genotypes (C and T). At the completion of PCR amplification, the genotype is determined by the amount of fluorescence (FAM or VIC) as measured using the Applied Biosystems 7500 Real-Time PCR system.

This test was developed and its performance characteristics determined by the DUHS Clinical Molecular Diagnostics Laboratory. It has not been cleared or approved by the U.S. Food and Drug Administration. This test is used for clinical purposes. It should not be regarded as investigational or for research. This laboratory is certified under the Clinical Laboratory Improvement Amendments of 1988 ("CLIA") as qualified to perform high complexity clinical testing.
   
   
Clinical Significance and Interpretive Data
    Interleukin 28B (IL28B) is a gene which encodes interferon-lambda-3. Like the interferon-alphas, interferon-lambdas are thought to play an important role in host response to viral infections. The IL28B gene locus contains a single nucleotide polymorphism (SNP, rs12979860) 3kb upstream of the coding sequence. At this SNP, two common alleles are possible, the C allele and the T allele, resulting in three possible genotypes: CC, CT, and TT. The frequency of these alleles vary widely across racial and ethnic groups, with the rs12979860 CC genotype being present in about 37% of Caucasian individuals, 14% of African American individuals and 29% of Hispanic individuals.

Genome wide association studies by several independent research groups have revealed a strong association between the rs12979860 genotype and viral response to peg-interferon alpha/ribavirin treatment in individuals with chronic HCV infections. When treated with peg-interferon/ribavirin, HCV infected individuals with the rs12979860 CC genotype have a more rapid decline in viral titers and higher probability of a sustained virologic response (SVR) than individuals with the CT or TT genotype. Specifically, Caucasian individuals with the CC genotype have an approximately 70% SVR rate vs. 33% and 27% for the CT and TT genotypes respectively. Similar SVR rates have been described in African Americans (48% SVR rate for CC genotype, 15% and 13% for CT and TT respectively) and Hispanics (56% SVR rate for CC genotype, 38% and 27% for CT and TT respectively). While the majority of the literature to date is on HCV genotype 1 infected individuals, recent studies indicate that the association of the rs12979860 genotype with SVR in patients infected with HCV is not limited to the highly prevalent HCV genotype Type 1, but also holds in HCV genotype 2, genotype 3 infected individuals.

References:

Clark PJ et al. IL28B Genomic-Based Treatment Paradigms for Patients With Chronic Hepatitis C Infection: The Future of Personalized HCV Therapies. Am J Gastroenterol. 2010 Oct 5.

Ge D et al. Genetic Variation in IL28B Predicts Hepatitis C Treatment-induced Viral Clearance. Nature 2009; 461(7262): 399-401.

Rauch A et al. Genetic Variation in IL28B is Associated with Chronic Hepatitis C and Treatment Failure: a Genome-wide Association Study. Gastroenterology 2010; 138: 133845.

Suppiah V et al. IL28B is Associated with Response to Chronic Hepatitis C Interferon-alpha and Ribavirin Therapy. Nat Genet 2009;41:11004.

Tanaka Y et al. Genome-wide Association of IL28B with Response to Pegylated Interferon-alpha and Ribavirin Therapy for Chronic Hepatitis C. Nat Genet 2009; 41: 11059.

Thompson AJ et al. Interleukin-28B polymorphism improves viral kinetics and is the strongest pretreatment predictor of sustained virologic response in hepatitis C virus-1 paitents. Gastroenterology. 2010 Jul; 139(1): 120-129.

Thomas DL et al . Genetic Variation in IL28B and Spontaneous Clearance of Hepatitis C Virus. Nature 2009; 461(7265): 798-801.

Mangia A et al. IL28B Polymorphism Determines Treatment Response of Patients with Hepatitis C Genotypes 2 or 3 who do not Achieve a Rapid Virologic Response. Gastroenterology 2010; 139: 821827.

Rall NI et al. Association of a Single Nucleotide Polymorphism near the Interleukin-28B Gene with Response to Hepatitis C Therapy in HIV/hepatitis C virus Co-infected Patients. AIDS 2010; 24: F23 9.
   
Indications
    HCV infected individuals with the rs12979860 CC genotype have a more rapid decline in viral titers and higher probability of a sustained virologic response (SVR) than individuals with the CT or TT genotype.
   
Limitations
    Many factors dictate the efficacy and appropriateness of antiviral therapy in patients with HCV infections including, ethnic or racial background, the HCV viral load and viral genotype. Thus, this assay is intended for use as an aid in developing patient specific treatment plans but is not a substitute for a complete pathologic and clinical evaluation, or physician's judgment and clinical experience.

This assay tests only for the rs12979860 SNP genotypes C and T within the IL28B gene. This assay does not detect any additional genetic variations in the IL28B gene. This test is subject to interference by various factors including PCR inhibitors, poor DNA quality and insufficient DNA quantity. These sources of interference usually produce an uninterpretable result rather and an inaccurate result. Although rare, mutations or polymorphisms occurring in the primer or probe binding regions can affect testing and could produce an inaccurate genotyping result. Genotyping patients using DNA obtained from peripheral blood leukocytes may not provide accurate information in patients who have had a bone marrow transplant or recent transfusion. To obtain an accurate genotype on a bone marrow transplant patient or recently transfused patient, buccal cells should be provided. For additional information or for help interpreting the results of this test, please contact the Clinical Molecular Diagnostics Laboratory.
   
Test Synonyms
  Synonym(s): HCV
Synonym(s): IL28B
Molecular Diagnostics Laboratory
(MDX)

Medical Director:
 Michael Datto, M.D., Ph.D.
 Phone: 919-684-6965
 Email: michael.datto@duke.edu
Lab Director:
 Catherine Rehder Ph.D, FACMG
 Phone: 919-613-8434
 Email: catherine.rehder@duke.edu
Lab Director:
 Siby Sebastian Ph.D., DABMG
 Phone: 919-613-8432
 Email: siby.s@duke.edu

Address: 
 Wadsworth Bldg, Cytogenetics, Rm 0220
 2351 Erwin Rd
 Durham,  NC  27705
 Phone: 919-684-2698
 FAX: 919-668-5424

Performing Times: