Hepatitis C Genotypes

The specific arrangement of genetic material within a virus is called the genotype. There are six main genotypes of the hepatitis C virus. Of the different hepatitis C genotypes, genotype 1 is the type most commonly found in the United States. Between 70 to 90 percent of Americans with hepatitis C have this genotype. Knowing which of the hepatitis C genotypes a person has is important because the genotype can affect the success of the treatment and determine how long the medications need to be taken.

 

Hepatitis C Genotypes: An Overview

Just as there are different types of hepatitis viruses, there are also a few different types of the hepatitis C virus itself. Though they all cause hepatitis C, each type of the virus has a slightly different arrangement of its genetic material, in this case called RNA. The specific arrangement of the RNA is called the genotype.
 
The main hepatitis C genotypes (also known as "subtypes") are known simply as:
 
  • Genotype 1
  • Genotype 2
  • Genotype 3
  • Genotype 4
  • Genotype 5
  • Genotype 6.
     

Which Hepatitis C Genotype Is Most Common?

Of the different hepatitis C genotypes, genotype 1 is the type most commonly found in the United States. Between 70 to 90 percent of Americans with hepatitis C have this genotype.
 
Hepatitis C virus genotypes 2 and 3 are less common. Only 10 to 20 percent of infected people in the US have either of these genotypes.
 

Why Do Hepatitis C Genotypes Matter?

The hepatitis C genotype matters because it can affect how successful a person's
 hepatitis C treatment will likely be, and how long the hepatitis C medication will need to be taken.
 
For example, it is estimated that up to 50 percent of the people with genotype 1 will have a sustained response, or successful treatment, with peginterferon and ribavirin. Patients with genotypes 2 and 3 are almost three times more likely than patients with genotype 1 to respond to therapy with alpha interferon or the combination of alpha interferon and ribavirin.
 
Furthermore, when using combination therapy, the recommended treatment length depends on the hepatitis C genotype. For patients with genotypes 2 and 3, a 24-week course of combination treatment is adequate, whereas for patients with genotype 1, a 48-week course is recommended.
 
For these reasons, testing for the hepatitis C genotype is often helpful. Once the genotype is identified, it does not need to be tested again -- hepatitis C genotypes do not change during the course of infection. There are other factors that can also affect your chances of having a successful treatment, so be sure to discuss your individual situation with your healthcare provider.
 
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Written by/reviewed by: Arthur Schoenstadt, MD
Last reviewed by: Arthur Schoenstadt, MD