A genotype is the “family” to which our specific virus belongs. Our genotype does not change, but we can be re-infected with a different genotype. The most common genotypes are as follows: 1a, 1b, 1c, 2a, 2b, 2c, 3a, 3b, 4, 5 and 3a has the highest response rate to interferon, and people with this genotype are generally younger in age and usually IV drug users.