Fig. 2

Temporal analysis of dhfr allele frequencies. (a) All dhfr mutations within Gambia, Mali, Ghana, and Kenya, (b) comparison of allele frequencies for individual dhfr mutations across countries. Lines represent the allele frequency of that mutation originating from homozygous genotypes only. Allele frequencies were calculated only for years with at least 25 homozygous samples (see Methods for further details). Significant increasing trends over time (Fisher’s exact test adjusted p-value < 0.05) are denoted with an asterisk (*). P-values were adjusted for multiple testing with a Benjamini and Hochberg correction¹⁵.