What is "genotyping" and why should I care?

Genotype refers to the genetic make-up the virus. There are 6 known genotypes and more than 50 subtypes of HCV.  Genotype 1 is the most common genotype seen in the United States. 

Genotype information is helpful in the study of how the virus is spread.  Knowing the genotype can help your doctor predict what drugs will work best and how long you should take them.

People with genotypes 2 and 3 are almost three times more likely than people with genotype 1 to respond to therapy with alpha interferon or the combination of alpha interferon and ribavirin.  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 HCV genotype is often clinically helpful. Once the genotype is identified, it need not be tested again; genotypes do not change during the course of infection.