Polymorphisms in Turkish population

CYP1A2, CYP2D6, GSTM1, GSTP1, and GSTT1 gene polymorphisms in patients with bladder cancer in a Turkish population.

Department of Medical Biology and Genetics, Faculty of Medicine, Ondokuz Mayis University, 55139, Samsun, Turkey.

Genetic differences in the metabolism of xenobiotics have recently been suggested as modifiers of individual susceptibility to bladder cancer (BC). The objective of this study was to investigate the relationship between bladder tumor and variants of cytochrome p450 1A2 (CYP1A2) 734 C –> A, cytochrome p450 2D6 (CYP2D6) 1934 G –> A, glutathione S-transferase M1, (GSTM1 null), glutathione S-transferase T1 (GSTT1 null), and glutathione S-transferase P1 (GSTP1) I105 V. We investigated the distribution of these polymorphisms in 135 BC patients and in 128 age and sex-matched cancer-free controls. The polymorphisms were analyzed using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay and the multiplex PCR method. Genotype and allele frequencies and their associations with BC risk, demographic factors, smoking status, and tumor stage were investigated. The prevalence of GSTT1 null genotype in cases was 23%, compared with 7% in the control group (OR = 3.94, 95% CI = 1.70-9.38, P = 0.001). There was no association between the studied polymorphisms of CYP1A2, CYP2D6, GSTM1, and GSTP1 genes and BC. There was an association between smoking status and BC. These data seem to indicate that GSTT1 gene polymorphism may be associated with BC in the Turkish population studied. Further studies will be needed to clarify the role of such variation in determining susceptibility to BC.

Department of Medical Biology and Genetics, Faculty of Medicine, Ondokuz Mayis University, 55139, Samsun, Turkey.

Genetic differences in the metabolism of xenobiotics have recently been suggested as modifiers of individual susceptibility to bladder cancer (BC). The objective of this study was to investigate the relationship between bladder tumor and variants of cytochrome p450 1A2 (CYP1A2) 734 C –> A, cytochrome p450 2D6 (CYP2D6) 1934 G –> A, glutathione S-transferase M1, (GSTM1 null), glutathione S-transferase T1 (GSTT1 null), and glutathione S-transferase P1 (GSTP1) I105 V. We investigated the distribution of these polymorphisms in 135 BC patients and in 128 age and sex-matched cancer-free controls. The polymorphisms were analyzed using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay and the multiplex PCR method. Genotype and allele frequencies and their associations with BC risk, demographic factors, smoking status, and tumor stage were investigated. The prevalence of GSTT1 null genotype in cases was 23%, compared with 7% in the control group (OR = 3.94, 95% CI = 1.70-9.38, P = 0.001). There was no association between the studied polymorphisms of CYP1A2, CYP2D6, GSTM1, and GSTP1 genes and BC. There was an association between smoking status and BC. These data seem to indicate that GSTT1 gene polymorphism may be associated with BC in the Turkish population studied. Further studies will be needed to clarify the role of such variation in determining susceptibility to BC.

Institute of Clinical Pharmacology, University Clinic Charité, Humboldt University, Berlin, Germany.

BACKGROUND AND OBJECTIVES: The genetically polymorphic cytochrome P450 enzymes 2Cl9 (CYP2Cl9) and 2D6 (CYP2D6) contribute to the metabolism of about 30% of all drugs. For analysis of the ethnic-related differences in drug disposition and as a preparation for routine genotyping, we examined CYP2C19 and CYP2D6 mutations in a large Turkish population. Methods: CYP2C19 and CYP2D6 alleles were determined with use of genomic deoxyribonucleic acid from 404 unrelated Turkish individuals. CYP2C19 alleles *1 to *5 and CYP2D6 alleles *1 to *12, and *14, *15, and *17 were measured by polymerase chain reaction-restriction fragment length polymorphism assays. RESULTS: From 404 subjects genotyped for CYP2C19, allele frequencies of CYP2C19*1 (wt), CYP2C19*2 (ml), and CYP2C19*3 (m2) were 0.88, 0.12, and 0.004, respectively; mutations m3 and m4 were not found. Four individuals (1.0%) were predicted to be poor metabolizers (CYP2C19*2/*2), a significantly lower frequency compared to Middle European populations. Among 404 subjects genotyped for CYP2D6, most frequent alleles were CYP2D6*1 (allele frequency 0.37), *2 (0.35), *4 (0.11), *10 (0.06), duplications *1×2, *2×2, or *4×2 (0.06), *5 (0.01), and *17(0.01). Overall, six subjects (1.49%) were predicted to be CYP2D6 poor metabolizers, and 35 subjects (8.66%) were predicted to be ultrarapid metabolizers as a result of CYP2D6 gene duplications. CONCLUSION: Obviously, within Europe there is a north-south gradient, with decreasing frequency of poor metabolizers of CYP2C19 and CYP2D6 to the south and a corresponding increase of ultrarapid metabolizers of CYP2D6. As in other white groups, only CYP2C19*2 plays a relevant role for the CYP2C19 poor metabolizer phenotype. The mutational spectrum of CYP2D6 indicated partial ethnic relationships to Asian and African populations.