CYP2B6*6single nucleotide polymorphism among patients with uncomplicated malaria in Adjumani district, Uganda: implications on efficacy of artemether-lumefantrine

CYP2B6, one of the most polymorphic enzymes, plays a major role in the metabolism of artemisinin and its derivatives. Variation in the frequency of the most common yet functionally deficientCYP2B6*6allele may impact artemisinin exposure, potentially contributing to differences in treatment outcomes. This study assessed the prevalence of theCYP2B6*6genotype among patients with uncomplicated malaria treated with artemether-lumefantrine at Adjumani District Hospital in the West Nile region, Uganda.

A total of 100 randomly selected patients with microscopically confirmed uncomplicatedP. falciparummalaria receiving artemether-lumefantrine (AL) were included in the study. Blood samples, 2-3 mL each, were collected using EDTA tubes on days 0 and 3 after AL administration. DNA was extracted using Qiagen DNA Mini kit. Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) was used to determine theCYP2B6*6genotype of the participants.P. falciparumpositivity was determined by microscopy and qPCR. For qPCR, parasite clearance was determined using comparative CT value. Data analysis was done using STATAver17.0 at a 95% significance level.

Among the malaria patients genotyped, 65% were female, and 35% were male, with a mean age of 17±10 years. TheCYP2B6*6variant allele frequency was 0.37, and the genotype frequency was 43% GG, 17% TT and 40% GT.P. falciparumday 3 microscopy positivity was 14% (6/43) among the GG, 37.5% (15/40) among the GT, and 17.64% (3/17) among the TT patients. PCR positivity rates were 58.1% (25/43) in the GG, 72.5% (29/40) in the GT, and 52.9% (9/17) in the TT patients. Heterozygous individuals (GT) had slow parasite clearance by a 10-fold difference compared to the homozygous (GG, TT) individuals (U=323.0;Z=-2.3442;p=0.019).

Malaria patients in Adjumani district had a high frequency of theCYP2B6*6variant allele. Interindividual variability inP. falciparumclearance exists, with heterozygous patients demonstrating slow artemether-lumefantrineP. falciparumparasite clearance. There is a need to consider incorporating host genomic factors, such as metabolising enzyme genotype into routine Therapeutic Efficacy Studies (TES).