Prevalence of G6PD candidate variants in malaria-endemic populations of northern Brazil

Glucose-6-Phosphate Dehydrogenase Deficiency (G6PDd) is the most prevalent enzymopathy worldwide and is particularly frequent in malaria-endemic regions. In Brazil, the distribution of G6PD variants is heterogeneous, with predominance of the African A- variant, although regional diversity remains incompletely characterized. This study aimed to genotype seven G6PD variants previously reported in Brazilian populations using a multiplex assay, to determine their frequencies among G6PD Deficient (G6PDd) individuals as well as in a malaria-endemic population from northern Brazil. This study was conducted including two groups from the states of Acre, Amazonas, and Rondônia. The first group comprised 63 males with known G6PD enzymatic status, enabling genotype-phenotype correlation. The second group included 481 individuals from rural communities to estimate population allele frequencies. The multiplex assay successfully genotyped all targeted variants in a single reaction. Among G6PD deficient individuals, 95.8% carried the African A- (376G/202A) variant, confirming its major contribution to G6PDd in this population. In the population-based group, allele frequencies were 7.0% for 376 G and 3.2% for 202A, with higher frequencies observed in Porto Velho, consistent with greater African ancestry. Strong linkage disequilibrium between 376 G and 202A was detected (D' = 1.0). The remaining variants were rare or absent. No significant association was observed between African G6PD variants and self-reported number of previous malaria episodes in statistical models adjusted for age, area of residence and genetic ancestry. This study demonstrates that multiplex SNaPshot® genotyping is a viable approach for targeted screening of the seven candidate G6PD variants. Despite the predominance of the G6PD A- variant in northern Brazil, regional differences in genetic ancestry likely lead to variable contributions of specific G6PD variants to the deficiency phenotype. Therefore, population-specific genetic surveillance is essential to support safer and more effective malaria treatment strategies in endemic areas.