Background: Cytochrome P450 (CYP) enzymes are essential in the metabolism of most drugs used today. Single nucleotide polymorphism(s) occurring in CYP genes can adversely affect drug pharmacokinetics, efficacy, and safety. Individuals carrying the CYP2C8*2 c.805A > T (CYP2C8*2; rs11572103) allele have impaired amodiaquine metabolism, increased risk of amodiaquine-related adverse events, and may promote the selection of drug-resistant parasite strains. This study investigated the distribution of the CYP2C8*2 allele in Brazzaville, Republic of Congo, where artesunate + amodiaquine is used as the secondline treatment for uncomplicated Plasmodium falciparum malaria. Methods: A total of 285 febrile children visiting the Marien Ngouabi paediatric hospital were genotyped for CYP2C8*2 using PCR-restriction fragment length polymorphism (PCR-RFLP). The allele frequencies and genotype distribution were determined. Results: The CYP2C8*2 allele was successfully genotyped in 75% (213/285) of the study participants. The CYP2C8*2A allele had a frequency of 63%, whereas the CYP2C8*2T allele had a frequency of 37%. Genotypes CYP2C8*2AA (rapid metabolizer), CYP2C8*2AT (intermediate metabolizer), and CYP2C8*2TT (poor metabolizer) were observed in 44%, 38%, and 18% of the investigated participants, respectively. Conclusions: This study gives the first description of CYP2C8*2 allele distribution in the Republic of Congo and highlights the potential risk of amodiaquine-related adverse events. Information from this study will be beneficial during pharmacovigilance investigations.

Background Malaria transmission-blocking anti-malarial drugs, such as primaquine, offers an effective strategy for reducing the incidence of falciparum malaria. However, this drug induces haemolytic anaemia among glucose-6-phosphate dehydrogenase (G6PD) deficient individuals. The distribution of G6PD deficiency in Brazzaville, Republic of Congo and the association of G6PD deficiency with haemoglobin levels and blood cell counts were investigated. Methods A total of 212 febrile children were recruited for this study. Plasmodium falciparum diagnosis was conducted by microscopy and nested PCR. Sanger sequencing was used to assess G6PD deficiency by detecting 202G>A (rs1050828) and 376A>G (rs1050829) single nucleotide polymorphisms. Results Two hundred and twelve children were successfully genotyped for G6PD variants. Overall, 13% (27/212) of the children were G6PD deficient and 25% (25/100) females were heterozygous (11 BA− and 14 A+A−). The remaining 160 children had a normal G6PD genotype. The mean red blood and mean platelet counts were significantly lower in hemizygous male (G6PD A−) participants than in normal male (G6PD A+ or B) participants ( p < 0.05). Conclusion This study gives an update on G6PD deficiency among Congolese children. Understanding the distribution of G6PD deficiency in other geographical regions is recommended before primaquine is adopted in the malaria control programme.

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A total of 418 patients with HIV-1 mono-infection, HIV-1 and Tuberculosis coinfection and symptomatic P. falciparum malaria were genotyped for the CYP2B6 c.516G>T SNP using Restriction Fragment Length Polymorphism (RFLP). The allele frequencies and genotype distributions were determined. Results: The CYP2B6 c.516G>T was successfully analysed in 69% (288/418) of the study participants. Among the investigated individuals, the distribution of the major allele CYP2B6*G was 45% and the minor CYP2B6*T allele was 55%. Significant differences in genotype distribution were also observed among the studied individuals. The CYP2B6*GG (rapid metabolizer) genotype was observed in 17% (49/288) followed by CYP2B6*GT (intermediate metabolizer) 55% (159/288) and CYP2B6*TT (poor metabolizers) 28% (80/ 288). Conclusion: This study contributes to increasing understanding on population pharmacogenetics and may help policy makers regulate treatment guidelines in the Congolese population with a high burden of HIV, Malaria and TB.

BackgroundThe inter-individual genetic polymorphism of cytochrome P450 enzymes (CYP), involved in the metabolism of many drugs, partly modulates drug response and toxicity. Single nucleotide polymorphisms of CYP2B6 for example, G516T have been implicated in high- and sub-therapeutic plasma concentration of the current antimalarial, HIV and TB first-line drugs in various geographical regions and thus undermines effective disease management. At present, there is no data on the frequency of CYP2B6 c.516G>T among the Congolese population, despite a significant number of people undergoing antimalarial, HIV and TB treatment that relies on CYP2B6-based drug clearance or activation.MethodsA total of 418 patients with HIV-1 mono-infection, HIV-1 +TB coinfection and P. falciparum infection were genotyped for CYP2B6 c.516G>T polymorphism using PCR-RFLP. The frequencies of the alleles as well as the genotypes (GG, GT and TT) were determined.ResultsThe frequency of CYP2B6 c.516G>T polymorphism was 69% and frequency of G and T alleles were 45% and 55%, respectively. 17.0% (49/288) of participants were GG (extensive metaboliser), 55.2% (159/288) of participants were GT (intermediate metaboliser) and 27.8% (80/288) of participants were TT (poor metabolisers).ConclusionThis study highlights CYP2B6 c.G516T polymorphism as a potential determinant of drug response and toxicity among the Congolese population, particularly those undergoing antiretroviral, malaria and tuberculosis treatment within the current first-line drug policy framework.