Extensive genetic diversity in the Plasmodium falciparum Na+/H+ exchanger 1 transporter protein implicated in quinine resistance.

The Plasmodium falciparum Na(+)/H(+) exchanger (Pfnhe-1) locus at chromosome 13 and another locus at chromosome 9 have recently been proposed to influence quinine resistance. Here, we sequenced the ms4760 locus of the Pfnhe-1 gene from 244 P. falciparum isolates collected from five different regions of India. A total of 16 different ms4760 alleles (with one to five DNNND repeats) were observed among these isolates. Interestingly, areas with a high prevalence of chloroquine and sulfadoxine-pyrimethamine resistance showed more Pfnhe-1 DNNND repeats compared to low drug resistance areas. The extent of genetic diversity at the ms4760 locus also varied from one region to another, with expected heterozygosity values ranging from 0.47 to 0.88.