The dhfr 59 and dhps 437 mutations associated with pyrimethamine and sulphadoxine resistance, respectively, were found significantly more frequently at the end of the malaria transmission season in parasites obtained from children in the intervention group than in those obtained from children in the control group, and this led to higher frequencies of the triple dhfr mutants and the quadruple mutant (triple dhfr + dhps 437) associated with significant resistance to SP in children who had received IPTc. The gene discussed is DHFR; the disease is malaria.