HEPATITIS C VIRUS (HCV) GENOTYPING
Label Name: HCV Geno
Lab Discipline: Molecular Diagnostics
Institution:  Duke University Health System 
EAP ID:  LAB915 
Last Review:  3/16/2017 2:52:09 PM
Specimen Type
  Blood
Container & Volume
  Age Group   Container   Volume  
  0  - 8 Years RED MICROTAINER 1  ML
  8 Years - 18 Years SERUM SEPARATOR TUBE 5  ML
Label Reminders
  Be sure to include patient's name, history #, date and time of collection, and collector's initials.
Collection Notes
  All:
  • Peripheral Blood: One serum seperator tube (minimum of 5 ml) is required for testing. For pediatric patients (age < 8 years) one red-top tube (minimum of 2 ml) is required. Forward unprocessed blood at ambient temperatures. Serum or plasma must be separated within 6 HOURS of collection. A delay in processing may artificially reduced the HCV viral levels to below detectable limits. UNPROCESSED SPECIMENS CANNOT BE FROZEN. GREEN-TOP (HEPARIN) TUBES ARE NOT ACCEPTABLE FOR TESTING.
 
Storage
  If there is a delay of greater than 6 hours, separate serum or plasma and freeze prior to shipping. Contact the Clinical Molecular Diagnostics Laboratory (919) 684-2698 with questions or for help processing or shipping samples.
Transport
  Unprocessed samples must arrive within 6 hours of collection. Serum or plamsa should be shipped frozen.

Turn Around Time -  Routine: 14-28 days   Stat: N/A
Reference Values
HCV Geno
HCV genotypes 1-6 and subtypes 1a and 1b
Methodology
  This test utilizes the eSensor® technology based method to determine HCV genotype. Purified RNA from an HCV positive sample is amplified using specific primers and a reverse transcription-PCR (RT-PCR) enzyme mix. The amplified DNA is converted to single stranded DNA via a series of enzymatic and biochemical reactions involving a pair of ferrocene-labeled signal probes that is specific to the different types/subtypes followed by a direct analysis on the electrochemical eSensor XT-8 detection system. The eSensor® HCV Genotype Test is designed to genotype all prevalent and clinically relevant HCV types/subtypes (1a, 1b, 2, 3, 4, 5, and 6). Results that have not previously been verified by our laboratory are confirmed by targeted HCV genome sequencing.

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
    BACKGROUND

Hepatitis C Virus (HCV) is an RNA virus that is a major cause of acute and chronic hepatitis both in the US and worldwide. Patients who are infected with HCV can have one of two outcomes: Some patients will have an acute infection and subsequently clear the virus. Other patients will become chronically infected with HCV. A subset of these chronically infected patients will have progressive liver disease, develop cirrhosis and ultimately have liver failure requiring liver transplantation. Currently there are two drugs that used in the treatment of hepatitis C; Peginterferon and Ribavirin. The efficacy, dose and duration or treatment with these drugs is determined in part by the HCV genotype.

HCV exhibits significant genetic variability within specific regions of the viral genome. This variability defines the HCV genotype. Six distinct HCV genotypes have been described. These genotypes can be further classified into subtypes, with more than 50 defined subtypes. Genotypes 1a and 1b are the most common types in Western Europe and the United States, followed by genotypes 2 and 3. Genotype 4 is found predominantly in Egypt; genotype 5 is found mainly in South Africa; and genotype 6 is found mainly in South East Asia.

CLINICAL UTILITY

The HCV genotype of an infected individual is the strongest indicator of response to therapy. Patients infected with HCV type 2 or 3 have a better (76-82%) probability of a sustained viralogic response (SVR) than patients who are infected in HCV type 1 (42-46%) when treated with peginterferon and ribaviran. In addition, patients who are infected with non-type 1 HCV require a shorter duration of therapy to achieve the optimal therapeutic benefit from treatment. The specific recommendations of the American Assocaition for the Study of Liver Diseases regarding HCV genotyping are quoted as follows (1):

The HCV genotype should be determined in all HCV-infected persons prior to treatment in order to determine the duration of therapy and likelihood of response.

For Genotype-1 HCV Infection (In patients who are candidates for peginterferon plus ribavirin)

• Treatment with peginterferon plus ribavirin should be planned for 48 weeks; the dose for peginterferon alfa-2a is 180 ug subcutaneously per week together with ribavirin using doses of 1,000 mg for those<75 kg in weight and 1,200 mg for those >75 kg; the dose for peginterferon alfa-2b is 1.5 ug/kg subcutaneously per week together with ribavirin using doses of 800 mg or those weighing <65 kg; 1,000 mg for those weighing >65 kg to 85 kg, 1,200 mg for >85 kg to 105 kg, and 1,400 mg for >105 kg.

• Treatment may be discontinued in patients who do not achieve an early virological response (EVR; >2 log reduction in HCV RNA at week 12 of treatment).

• Patients who do not achieve a complete EVR (undetectable HCV RNA at week 12 of treatment) should be re-tested at week 24, and if HCV RNA remains positive, treatment should be discontinued.

• For patients with genotype 1 infection who have delayed virus clearance (HCV RNA test becomes negative between weeks 12 and 24), consideration should be given to extending therapy to 72 weeks.

• Patients with genotype 1 infection whose treatment continues through 48 to 72 weeks and whose measurement of HCV RNA with a highly sensitive assay is negative at the end of treatment should be retested for HCV RNA 24 weeks later to evaluate for a sustained virological response (SVR; HCV RNA negative 24 weeks after cessation of treatment).

For Genotype-2 or Genotype-3 HCV Infection (In patients who are candidates for peginterferon plus ribavirin)

• Treatment with peginterferon plus ribavirin should be administered for 24 weeks, using a ribavirin dose of 800 mg.

• Patients whose treatment continues through 24 weeks and whose measurement of HCV RNA with a highly sensitive assay is negative should be retested for HCV RNA 24 weeks later to evaluate for an SVR.

REFERENCES:

1. Ghany MG, Strader DB, Thomas DL, et al., Diagnosis, management, and treatment of hepatitis C: an update. Hepatology. 2009; 49(4):1335-1374.

2. McHutchison JG, Gordon SC, Schiff ER, et al. Interferon alfa-2b alone or in combination with ribavirin as initial treatment for chronic hepatitis C. N Engl J Med. 1998; 339: 1485-1492.

3. Poynard T, Marcellin P, Lee SS, et al. Randomised trial of interferon a2b plus ribavirin for 48 weeks or for 24 weeks versus interon a2b plus placebo for 48 weeks for treatment of chronic infection with hepatitis C virus. Lancet. 1998; 352: 1426-1432.

4. Fried MW, Shiffman ML, Reddy KR, et al. Peginterferon alfa-2a plus ribavirin for chronic hepatitis C virus infection. N Engl J Med. 2002; 347:975-982.

5. NIH Consensus Statement on Management of Hepatitis C: 2002. http://consensus.nih.gov/cons/116/hepatitis_c_consensus.pdf
   
Indications
    The HCV genotype should be determined in all HCV-infected persons prior to treatment in order to determine the duration of therapy and likelihood of response.
   
Limitations
    Occasionally indeterminate genotype interpretation may result. In such cases, 5'UTR and/or NS5b region sequencing is performed to determine genotype.

Indeterminate or (rarely) inaccurate patterns may result from 5'UTR and/or core binding region polymorphisms, mixed infections, or the presence of a rare or unclassified strain.

Up to 4% of US HCV cases show co-infection with more than one strain. In such cases, only the dominant strain may be genotyped, or multiple strains may produce confounding results.

HCV strains sequestered to tissues other than blood will not be genotyped.

Hemolyzed samples and samples collected in heparin may inhibit PCR and result in un-interpretable or inaccurate results.

This assay may not produce results for samples with a HCV viral load <1,000 IU/mL serum. Only HCV genotypes 1-6 and subtypes 1a and 1b will be reported.


For additional information or for help interpreting the results of this test, please contact the Clinical Molecular Diagnostics Laboratory (919-684-2698).
   
Test Synonyms
  Synonym(s):  Hep C typing
Synonym(s):  Hepatitis C viral typing
Synonym(s): HCV genotyping
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: