In the Amazon, the treatment for Plasmodium vivax is chloroquine plus primaquine. However, this regimen is limited due to the risk of acute hemolytic anemia in glucose-6-phosphate dehydrogenase deficiency. Primaquine is a prodrug that requires conversion by the CYP2D6 enzyme to be effective against malaria. A series of cases were performed at an infectious diseases reference hospital in the Western Brazilian Amazon. The STANDARD G6PD (SD Biosensor^®) assay was used to infer G6PD status and real-time PCR to genotype G6PD, CYP2C19, CYP2D6 and CYP3A4. Eighteen patients were included, of which 55.6% had African A− variant (G202A/A376G), 11.1% African A+ variant (A376G), 5.6% Mediterranean variant (C563T) and 27.8% were wild type. CYP2C19, CYP2D6 and CYP3A4 genotyping showed no statistically significant differences in the frequency of star alleles between the groups G6PD deficient and G6PD normal. Elevated levels of liver and kidney markers in the G6PDd patients were observed in gNM, gRM and gUM of CYP2C19 and CYP2D6 (p < 0.05). Furthermore, in this study there was no influence of CYPs on hemolysis. These findings reinforce the importance of studies on the mapping of G6PD deficiency and genetic variations of CYP2C19, CYP2D6 and CYP3A4. This mapping will allow us to validate the prevalence of CYPs and determine their influence on hemolysis in patients with malaria, helping to decide on the treatment regimen.

Background/Objectives: Pharmacogenetics (PGx) aims to identify individuals more likely to suffer from adverse reactions or therapeutic failure in drug treatments. However, despite most of the evidence in this area being from European populations, some diseases have also been neglected, such as HIV infection, malaria, and tuberculosis. With this review, we aim to emphasize which pharmacogenetic tests are ready to be implemented in treating neglected diseases that have some evidence and call attention to what is missing for these three diseases. Methods: A critical literature review on the PGx of HIV infection, malaria, and tuberculosis was performed. Results: There are three PGx guidelines for antiretroviral drugs used in HIV infection, one for malaria, and none for tuberculosis. Some evidence is already available, and some genes have already been identified, such as CYP2D6 for primaquine treatment and NAT2 for isoniazid. However, some barriers to the implementation are the lack of evidence due to the few studies on the diseases themselves and the admixture of the most affected populations, which must be considered, given the genetic differentiation of these populations. Conclusions: PGx tests such as abacavir are already implemented in some places, and efavirenz/atazanavir is ready to implement if this medication is used. Other gene–drug associations were found but still do not present a clear recommendation. We call attention to the need to generate more evidence for testing treatments for other neglected diseases, such as malaria and tuberculosis, given their epidemiological importance and for the public health of less favored populations.