Strong association, but incomplete correlation, between chloroquine resistance and allelic variation in the pfmdr-1 gene of Plasmodium falciparum isolates from India.

The increasing prevalence of chloroquine-resistant Plasmodium falciparum has complicated the control of falciparum malaria. It has been suggested that point mutations at nucleotide positions 754, 1049, 3598, 3622 and 4234 in the parasite's pfmdr-1 gene are associated with such resistance, although this is a matter of controversy. Eighteen chloroquine-sensitive and 22 resistant isolates of P. falciparum from India were investigated, to examine the role of the pfmdr-1 gene in the resistance, and to determine whether any of the point mutations could be used as a marker for the rapid identification of the chloroquine-resistant strains. As this investigation failed to reveal an explicit association between allelic variation in the pfmdr-1 gene and chloroquine resistance, the use of point mutations to identify the resistant strains does not appear feasible.