The influence of CYP2D6 and CYP2C19 genetic variation on diabetes mellitus risk in people taking antidepressants and antipsychotics.

Background CYP2D6 and CYP2C19 enzymes are essential in the metabolism of antidepressants and antipsychotics. Genetic variation in these genes may increase risk of adverse drug reactions. Antidepressants and antipsychotics have previously been associated with risk of diabetes. We examined whether individual genetic differences in CYP2D6 and CYP2C19 contribute to these effects. Methods We identified 31,579 individuals taking antidepressants and 2,699 taking antipsychotics within UK Biobank. Participants were classified as poor, intermediate or normal metabolisers of CYP2D6, and as poor, intermediate, normal, rapid and ultra-rapid metabolisers of CYP2C19. Risk of diabetes mellitus represented by HbA1c level was examined in relation to the metabolic phenotypes. We analysed drugs either individually (where sample size permitted) or grouped by class. Results CYP2D6 poor metabolisers taking paroxetine had higher Hb1Ac than normal metabolizers (mean difference: 2.29mmol/mol; p < 0.001). Among participants with diabetes who were taking venlafaxine, CYP2D6 poor metabolisers had higher HbA1c levels compared to normal metabolisers (mean differences: 10.15 mmol/mol; p < 0.001. Among participants with diabetes who were taking fluoxetine, we observe that CYP2D6 intermediate metabolisers and decreased HbA1c, compared to normal metabolisers (mean difference -7.74mmol/mol; p=0.017). We did not observe any relationship between CYP2D6 or CYP2C19 metabolic status and HbA1c levels in participants taking antipsychotic medication. Conclusion Our results indicate that the impact of genetic variation in CYP2D6 differs depending on diabetes status. Although our findings support existing clinical guidelines, further research is essential to inform pharmacogenetic testing for people taking antidepressants and antipsychotics.

Genetic polymorphisms of CYP2C9, CYP2C19, and CYP3A5 in Kosovar population

Cytochrome P450 genetic polymorphisms are responsible for individual variations in drug metabolism and drug-drug interactions. They are very important for pharmacogenetics, and their frequency varies across different populations. There is a big gap in the knowledge about the CYP gene family polymorphisms in the population of Kosovo, and the aim of our study was to fill that gap by determining the frequency of the most important variant alleles of CYP2C9, CYP2C19, and CYP3A5 in 234 nonrelated Kosovars. The allele frequencies of CYP2C9*2 and 2C9*3 were 17.52 %, and 10.89 %, respectively. Sixteen participants (6.81 %) were CYP2C9 poor metabolisers. The CYP2C19*2 and *17 variant frequencies were 13.03 % and 19.01 %, respectively. There were 2.13 % CYP2C19 poor and 4.27 % ultra-rapid metabolisers (homozygous carriers of the *17 allele). With regard to CYP3A5, the frequency of the *3 variant allele was 98.29 % (non-expressors), while the remaining participants (1.70 %) were expressors of CYP3A5. These findings are comparable with other European ethnicities, specifically those of Southeast Europe.

Antipsychotic drug-induced movement disorders in schizophrenics in relation to CYP2D6 genotype

BackgroundApproximately 5–10% of Caucasians (poor metabolisers) show impaired metabolism of at least 20 therapeutically important drugs, including a number of commonly used antipsychotic agents, because they lack the cytochrome p450 enzyme CYP2D6. The molecular basis of this defect is now well understood and simple genotyping tests using the polymerase chain reaction (PCR) have been developed.MethodTo determine whether poor metabolisers are more susceptible to acute dystonic reactions and chronic movement disorders associated with the administration of antipsychotic drugs, we determined CYP2D6 genotypes in a group of 76 schizophrenics using previously described methods involving PCR and restriction fragment length polymorphism analysis.ResultsThere was no difference in genotype frequencies between the schizophrenics and a normal control population, suggesting that CYP2D6 genotype was not a factor in determining susceptibility to the disease. However, four of the five poor metabolisers compared with 44% of the remaining subjects were suffering from a movement disorder at the time of the study, although because of the small number of poor metabolisers in the group the difference was not statistically significant. Poor metabolisers were not more likely to suffer an acute dystonic reaction.ConclusionsCYP2D6 genotype is not a determinant of susceptibility to acute dystonic reactions but may be a contributory factor in antipsychotic drug-induced movement disorders including tardive dyskinesia.