The alleles 51-isoleucine, 59-arginine, and 108-serine of DHFR were significantly associated with clinical resistance, as was allele 581-alanine of DHPS.
The present study was designed to characterize mutations in dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS) genes of Plasmodium falciparum in the Bolivar region of Venezuela, where high levels of clinical resistance to sulfadoxine-pyrimethamine (SP, Fansidar; F. Hoffman-La Roche, Basel, Switzerland) has been documented.