Drug resistance. An updated, user-friendly guide to genotype interpretation

Genotypic antiretroviral resistance testing (GART) has been shown to be of value in selecting antiretroviral therapy. Unfortunately, GART reports often are difficult to interpret and, at times, can be misleading. Published lists of "primary" resistance mutations often do not include the combinations of "secondary" mutations, which also limit the efficacy of antiretroviral agents. This article tries to rectify this situation by introducing a general approach to genotype interpretation and by providing more "user-friendly" tables of key single mutations and key mutation combinations.