HCV-Genotyping by sequencing

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No Fasting Required

Details

It analyzes a portion of the HCV RNA genome to determine the viral strain

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HCV-Genotyping by Sequencing

Why is it done?
- Identifies the specific genotype of hepatitis C virus (HCV) through direct DNA/RNA sequencing of the viral genome
- Determines treatment regimen selection, as different HCV genotypes respond differently to antiviral medications
- Guides duration and type of direct-acting antiviral (DAA) therapy required for each patient
- Performed in all patients with confirmed HCV antibody or HCV RNA positive results
- Used to detect treatment-resistant mutations or viral variants in patients with virologic failure
- Assists in epidemiological studies and transmission route tracking
- Typically performed at time of initial HCV diagnosis or when initiating antiviral therapy
Normal Range
- HCV Genotypes Identified: Genotype 1, 2, 3, 4, 5, 6, 7, 8, or mixed genotypes
- Normal Result: No HCV RNA detected or undetectable HCV RNA (indicating successful treatment or absence of infection)
- Abnormal Result: Detection of HCV RNA with specific genotype identification (Genotypes 1-7 worldwide, with 1 being most prevalent in developed nations)
- Units of Measurement: Genotype designation (qualitative), typically with viral load expressed in International Units per milliliter (IU/mL)
- Interpretation: Test is qualitative for genotype identification; presence of any detectable HCV RNA is considered abnormal and indicates active infection requiring treatment
Interpretation
- Genotype 1 (most common globally): Most prevalent in North America and Europe; traditionally required 24 weeks of treatment; now treatable with 8-12 weeks of DAA therapy. Subtype 1a and 1b have slightly different treatment responses.
- Genotype 2: Generally has better treatment response; typically cured with 8-12 weeks of DAA therapy; generally more favorable prognosis
- Genotype 3: Associated with rapid fibrosis progression and higher risk of cirrhosis; may have lower DAA cure rates; requires specific drug combinations; associated with hepatic steatosis
- Genotype 4: Most prevalent in Middle East and Africa; intermediate treatment response; typically requires 12 weeks of DAA therapy
- Genotypes 5, 6, 7: Rare globally; genotype 5 found in South Africa; genotype 6 in Southeast Asia; genotype 7 identified in Central Africa. All respond well to modern DAA regimens.
- Mixed Genotypes: Presence of two or more genotypes simultaneously; requires treatment targeting the most difficult-to-treat genotype present
- No HCV RNA Detected: Indicates either absence of HCV infection or successful viral eradication following treatment (sustained virologic response)
- Factors Affecting Results: Viral load level (sensitivity increases with higher viral loads), timing of sample collection relative to infection, prior treatment history, presence of resistance-associated variants, specimen quality and handling
- Resistance Mutations: Sequencing may reveal resistance-associated substitutions (RAS) that confer reduced susceptibility to specific DAAs, particularly in treatment-experienced patients or those with virologic failure
Associated Organs
- Primary Organ System: Hepatic system (liver); HCV primarily replicates in hepatocytes and causes chronic hepatic inflammation
- Chronic Hepatitis C: Persistent viral infection leading to chronic inflammation, hepatocyte damage, and progressive liver disease
- Cirrhosis: Progressive fibrosis resulting in severe liver scarring and loss of hepatic function; genotype 3 particularly associated with rapid fibrosis progression
- Hepatocellular Carcinoma (HCC): Primary liver malignancy; significant risk in advanced cirrhosis; genotype may influence HCC risk profile
- Hepatic Steatosis: Fatty infiltration of liver; particularly associated with genotype 3 infection
- Portal Hypertension: Elevated blood pressure in portal vein due to cirrhotic changes; leads to varices, ascites, and hepatic encephalopathy
- Extrahepatic Manifestations: Cryoglobulinemia (blood vessels), glomerulonephritis (kidneys), lymphomas, thyroid disorders, and neurological manifestations
- Potential Complications: End-stage liver disease, liver failure, variceal bleeding, hepatic encephalopathy, renal impairment, increased cardiovascular risk, and increased mortality if untreated
Follow-up Tests
- HCV RNA Quantitation (Viral Load): Measures level of viral replication; essential for assessing disease activity and treatment response; performed at baseline and during/after therapy
- Liver Function Tests (LFTs): ALT, AST, alkaline phosphatase, bilirubin, albumin; assess hepatic synthetic and metabolic function; abnormalities indicate liver injury
- Liver Biopsy or Elastography: Assess degree of fibrosis and cirrhosis; elastography (transient or acoustic radiation force impulse) non-invasively measures liver stiffness; guides treatment urgency
- Fibrosis Markers (FIB-4, APRI): Noninvasive blood-based markers incorporating platelet count and transaminases; help stratify cirrhosis risk
- Hepatitis A and B Serologies: Assess immunity and potential coinfection; vaccination recommended if non-immune
- HIV and Syphilis Testing: Recommended in all HCV patients due to shared transmission routes; coinfection affects treatment algorithms
- Resistance-Associated Variant (RAV) Testing: Performed if treatment fails or in retreatment cases; identifies mutations causing DAA resistance
- Post-treatment Monitoring: HCV RNA at 4, 12, and 24 weeks post-treatment to confirm sustained virologic response (SVR); annual ultrasound/HCC screening if cirrhosis present
- Imaging Studies: Ultrasound, CT, or MRI for cirrhotic patients to screen for HCC; may be repeated every 6-12 months depending on risk
- Coagulation Studies (PT/INR): Assess hepatic synthetic function; abnormalities indicate advanced cirrhosis or liver failure
Fasting Required?
- Fasting Requirement: No - HCV-Genotyping by sequencing does not require fasting; the test can be performed on blood samples collected at any time of day
- Specimen Collection: Typically 5-10 mL of whole blood collected in EDTA (ethylenediaminetetraacetic acid) lavender-top tube or plasma separator tube per laboratory protocols
- Sample Handling Requirements: Sample must be handled carefully to preserve RNA integrity; typically refrigerated at 2-8°C if not processed immediately; transport to laboratory promptly (within 24 hours preferred)
- Medications to Avoid: No specific medications need to be withheld; test can be performed regardless of antiretroviral or other medication use
- Patient Preparation: No special preparation required; patient can eat, drink, and take medications normally; may want to advise patient to stay hydrated for easier blood draw
- Timing Considerations: For optimal sensitivity, test should be performed when HCV RNA levels are detectable (generally after 1-2 weeks of infection and before viral clearance); avoid testing during window period in acute infection

How our test process works!