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 Genotype Is Most Common?
Of the different genotypes of hepatitis C, 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 U.S. have either of these genotypes.
Why Do the Genotypes of Hepatitis C Matter?
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 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 genotype of hepatitis C 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.
