Yeganeh N, et al. - Researchers aimed at evaluating the prevalence and the effect of antiretroviral drug-associated resistance mutations (DRMs) in previously untreated mother-infant pairs. Using a case-control design of 1:4 (1 transmitter to 4 nontransmitters), they evaluated DRMs as a predictor of human immunodeficiency virus (HIV) mother-to-child transmission (MTCT) in specimens obtained from mother-infant pairs. They performed ViroSeq HIV-1 genotyping on mother-infant specimens to assess for clinically relevant DRMs. Findings suggested a common occurrence of preexisting DRMs in untreated HIV-infected pregnant women, but it did not increase the risk of HIV MTCT. However, women with DRMs with no virological suppression could transmit resistant mutations, complicating infant management.