Analysis of the key pfcrt point mutation and in vitro and in vivo response to chloroquine in Yaounde', Cameroon

The putative key codon (Lys-76 in sensitive parasites and Thr-76 in resistant parasites) of the novel candidate gene for chloroquine resistance, Plasmodium falciparum chloroquine resistance transporter (pfcrt), was determined by polymerase chain reaction-restriction fragment length polymorphism from 111 Cameroonian isolates and was compared with in vivo and in vitro responses to chloroquine. The key codon was significantly associated (P < .001) with responses in vivo (92% sensitivity and 76% specificity) and in vitro (97% sensitivity and 81% specificity). Some discordant results were due to multiclonal infections. The high, but not perfect, correlation between the pfcrt polymorphism and the phenotype implies that a single point mutation in codon 76 of the pfcrt gene is the major, but possibly not the sole, determinant for chloroquine resistance.