The CYP2B6 G516T polymorphism influences CD4+ T-cell counts in HIV-positive patients receiving antiretroviral therapy in an ethnically diverse region of the Amazon

- The frequency of the CYPB2B G516T polymorphic allele is influenced by the ethnicity of the population.
- The polymorphism is not directly correlated with liver and kidney toxicity associated with the use of antiretrovirals.
- The homozygous polymorphic genotype (TT) is associated with lower CD4+ T-cell counts in patients using efavirenz in a genetically diverse region.

SummaryObjectivesCytochrome P450 (CYP) enzyme polymorphisms seem to significantly influence the variability of the responses to certain antiretroviral drugs and their toxicity levels. The objective of this study was to evaluate the influence of the CYP2B6 G516T polymorphism on hepatic, renal, immunological, and viral marker changes in HIV-1-positive patients receiving treatment in an ethnically diverse region of the Amazon.MethodsCYP2B6 G516T genotyping was performed by real-time PCR (RT-PCR) in samples from 185 patients. Urea, creatinine, aspartate aminotransferase (AST), alanine aminotransferase (ALT), CD4+/CD8+ T-cell counts, and HIV-1 plasma viral load were measured.ResultsThe polymorphic CYP2B6 G516T allele frequency was 0.36, which is different from the frequencies in other ethnic groups. The polymorphic genotype was associated with changes in the urea and ALT levels, although the median values were within the normal range. The TT genotype was also associated with significantly lower CD4+ T-cell counts in patients using efavirenz.ConclusionsThe CYP2B6 G516T polymorphism seems to affect the response to efavirenz treatment by reducing CD4+ T-cell counts in patients with a high degree of miscegenation who use this antiretroviral agent.