On the other hand, polymorphisms in pfmdr1 were also associated with CQ resistance early on [63] . While CQS isolates had identical PfMDR1 sequences, there were five changes in CQR isolates. In strains K1 and ITG2, N86Y was the only change. CQR strain 7G8 had four changes; Y184F, S1034C, N1042D and D1246Y [63] . The Y184F mutation was postulated as not likely to be involved in CQ resistance since it was also found in CQS strains. Thus, the pfmdr1 overexpression hypothesis was revised to suggest that CQR strains expressed mutant PfMDR1 but did not necessarily overexpress wild-type [63] . (Which pfmdr alleles are considered 'mutant' versus 'wild-type' is open to interpretation, wild-type is used here to refer to the allele found in the CQS strain HB3.) Interestingly, CQR K1 versus 7G8 polymorphisms appear to be geographically biased [64] [65] [66] .