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To date, few or no data concerning the prevalence of polymorphisms in drug metabolism genes of antiretroviral drugs have been reported in the Argentinean population or in porphyric individuals worldwide. The purpose of the current investigation was to determine whether interindividual differences in cytochrome P450 3A5 (CYP3A) and 2B6 (CYP2B6) genes could influence the triggering of Porphyria Cutanea Tarda (PCT) in subjects with human immunodeficiency virus (HIV) after antiretroviral exposure.
A total of 141 subjects, 60 control volunteers and 81 unrelated individuals with PCT were included in the study. In the porphyric group, 21 individuals were HIV positive. To evaluate the presence of the alleles CYP3A5*3, CYP3A5*6 and CYP2B6*6 a polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) analysis was performed.
The frequencies of CYP3A5*3 were 0.91 in control group, 0.89 in PCT patients and 0.89 in PCT-HIV. CYP2B6*6 frequencies were 0.31 in control group, 0.34 in PCT group and 0.30 in PCT-HIV group. We have shown that the allelic frequencies of CYP3A5*3 or CYP2B6*6 in our population were similar to those reported for other Caucasian populations. Although, we have not found significant differences in polymorphisms of CYP3A5 and CYP2B6 between the different groups analyzed, there are an enormous number of biological variables that may influence antiretroviral treatment, like other genetic polymorphisms of phase I or phase II enzymes, or transporters like multidrug resistance transporter gene (MDR1), which can contribute to antiretroviral drug toxicities and response or even it is possible that the PCT-HIV association has more than one factor responsible for the onset of PCT symptoms.