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Hepatitis C Genotypes

Different genotypes of the hepatitis C virus have different numerical and geographical distributions. Although infection with any of the different genotypical types of hepatitis C leads to basically the same effects, it is important for physicians to determine which genotype has caused infection in a given individual in order to make appropriate treatment decisions.

  1. Definition

    • A genotype is a description of something based on its genetic material, which is stored in RNA in the case of hepatitis C. This is opposed to phenotype, the way something looks as a result of its genetic material.

    Types

    • Several different genotypes of hepatitis C virus cause disease in different parts of the world, according to the National Digestive Disease Information Clearinghouse (NDDIC). These are labeled 1-6 with an additional letter to indicate subtype: 1a and 1b are responsible for between seventy and eighty per cent of the infection in the United States; 2 and 3 make up most of the rest of infections.

    Testing

    • Laboratory analysis of a sample of blood taken from an infected individual can yield its genotype, according to the Mayo Clinic. Genotyping is important in the United States because the form of the virus that causes most infections (1) does not respond as positively to treatment as do types 2 and 3.

    Treatment

    • Treatment for hepatitis C consists of interferon, ribavirin or, most commonly, a combination of the two. People with hepatitis C genotypes 2 and 3 are commonly cleared of the virus after 24 weeks of treatment, while those with genotype 1 typically require 48 weeks of treatment. Testing for the presence of hepatitis RNA throughout the course of treatment indicates whether or not an individual is responding to drug therapy, according to the NDDIC.

    Prevention

    • The large number of genotypes of the hepatitis C virus is a barrier to developing a vaccine for the virus. This is because a useful vaccine would have to protect inoculated individuals against all the genotypes of the virus, something difficult to accomplish through the use of a single vaccine.

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