The involvement of Pfmdr1 (Plasmodium falciparum multidrug resistance 1) polymorphisms in antimalarial drug resistance is still debated. Here, we evaluate the association between polymorphisms in Pfmdr1 (N86Y, Y184F, S1034C, N1042D, and D1246Y) and Pfcrt (K76T) and in vitro responses to chloroquine (CQ), mefloquine (MQ), lumefantrine (LMF), quinine (QN), monodesethylamodiaquine (MDAQ), and dihydroartemisinin (DHA) in 174 Plasmodium falciparum isolates from Dakar, Senegal. The Pfmdr1 86Y mutation was identified in 14.9% of the samples, and the 184F mutation was identified in 71.8% of the isolates. No 1034C, 1042N, or 1246Y mutations were detected. The Pfmdr1 86Y mutation was significantly associated with increased susceptibility to MDAQ (P=0.0023), LMF (P=0.0001), DHA (P=0.0387), and MQ(P=0.00002). The N86Y mutation was not associated with CQ (P=0.214) or QN (P=0.287) responses. The Pfmdr1 184F mutation was not associated with various susceptibility responses to the 6 antimalarial drugs (P=0.168 for CQ, 0.778 for MDAQ, 0.324 for LMF, 0.961 for DHA, 0.084 for QN, and 0.298 for MQ). The Pfmdr1 86Y-Y184 haplotype was significantly associated with increased susceptibility to MDAQ (P= 0.0136), LMF (P=0.0019), and MQ (P=0.0001). The additional Pfmdr1 86Y mutation increased significantly the in vitro susceptibility to MDAQ (P<0.0001), LMF (P<0.0001),MQ(P<0.0001), and QN (P=0.0026) in wild-type Pfcrt K76 parasites. The additional Pfmdr1 86Y mutation significantly increased the in vitro susceptibility to CQ (P=0.0179) in Pfcrt 76T CQ-resistant parasites.
