Hepatitis C Genotypes
The hepatitis C genotype can affect which medications are chosen, how successful the treatment will be and how long the hepatitis C medication will need to be taken.
Hepatitis C is divided into six distinct genotypes throughout the world with multiple subtypes in each genotype class. A genotype is a classification of a virus based on the genetic material in the RNA (Ribonucleic acid) strands of the virus. Generally, patients are only infected with one genotype, but each genotype is actually a mixture of closely-related viruses called quasi-species. These quasi-species have the ability to mutate very quickly and become immune to current treatments, which explains why chronic Hepatitis C is so difficult to treat.
Following is a list of the different genotypes of chronic Hepatitis C:
Genotype 2a, 2b, 2c & 2d
Genotype 3a, 3b, 3c, 3d, 3e & 3f
Genotype 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, 4i & 4j
Genotype 1 is the most common type of Hepatitis C genotype in the United States and the most difficult to treat .Between 70 to 90 percent of Americans with hepatitis C have this genotype. For physicians, knowing the genotype of Hepatitis C is helpful in making a therapeutic recommendation. Individuals with genotypes 2 and 3 are almost three times more likely than individuals 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 duration of treatment depends on the genotype. Only 10 to 20 percent of infected people in the U.S. have either of these genotypes.
For this reason, testing for Hepatitis C genotype is often clinically helpful. Once the genotype is identified, it need not be tested again as genotypes do not change during the course of infection.
Furthermore, when using combination therapy, the recommended treatment length depends on the genotype. Depending on the genotype and the treatment regimen, treatment may be as short as 12 weeks or as long as 48 weeks.
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.