Balkan Med J 2012; 29: 252-60 • DOI: 10.5152/balkanmedj.2012.039 252 Original Article © Trakya University Faculty of Medicine Polymorphisms of Cytochrome P450 Genes in Three Ethnic Groups from Russia Gülnaz Korytina1, Olga Kochetova1, Leysan Akhmadishina1, Elena Viktorova2, Tatyana Victorova1 1Institute of Biochemistry and Genetics, Genomics, Ufa, Russian Federation 2George-August University of Göttingen, Genomics, Göttingen, Germany ABSTRACT Objective: To determine the prevalence of the most common allelic variants of CYP1A1, CYP1A2, CYP1B1, CYP2C9, CYP2E1, CYP2F1, CYP2J2 and CYP2S1 in a representative sample of the three ethnic groups (Russians, Tatars and Bashkirs) from Republic of Bashkortostan (Russia), and compare the results with existing data published for other populations. Material and Methods: CYPs genotypes were determined in 742 DNA samples of healthy unrelated individuals representative of three ethnic groups. The CYPs gene polymorphisms were examined using the PCR-RLFP method. Results: Analysis of the CYP1A1 (rs1048943, rs4646903), CYP1A2 (rs762551), CYP2E1 (rs2031920) allele, genotype and haplotype frequencies revealed significant differences among healthy residents of the Republic of Bashkortostan of different ethnicities. Distribution of allele and genotype frequen- cies of CYP1A2 (rs35694136), CYP1B1 (rs1056836), CYP2C9 (rs1799853, rs1057910), CYP2F1 (rs11399890), CYP2J2 (rs890293), CYP2S1 (rs34971233, rs338583) genes were similar in Russians, Tatars, and Bashkirs. Analysis of the CYPs genes allele frequency distribution patterns among the ethnic groups from the Republic of Bashkortostan in comparison with the different populations worldwide was conducted. Conclusion: The peculiarities of the allele frequency distribution of CYPs genes in the ethnic groups of the Republic of Bashkortostan should be taken into consideration in association and pharmacogenetic studies. The results of the present investigation will be of great help in elucidating the genetic background of drug response, susceptibility to cancer and complex diseases, as well as in determining the toxic potentials of environmental pollutants in our region. Key Words: Pharmacogenetics, genetic polymorphism, ethnic-related differences CYPs variants in three ethnic groups from Russia Received: 05.10.2011 Accepted: 22.05.2012 Introduction sion involves tissue specific factors, each binding to a certain regulatory element in the 5’ terminal gene region (1-4). The human cytochrome P450 superfamily (CYPs) includes CYPs gene polymorphisms differ markedly in frequency 57 functionally active genes. Genetic polymorphisms in CYPs among different ethnic and racial groups (2, 3, 5, 6). may influence inter-individual variation in human sensitivity to The Republic of Bashkortostan is located in the Southern damaging environmental factors and predisposition to com- part of the Urals. It is a sovereign state under the jurisdiction plex diseases. of Russia. The Republic of Bashkortostan has an exclusive loca- CYPs belong to a group of enzymes that metabolize hun- tion on the border of two continents - Europe and Asia. Repre- dreds of various compounds. Enzymes of the group facilitate sentatives of 70 nations and ethnicities live in the Republic of the incorporation of activated oxygen directly into a substrate Bashkortostan, including Russians (39.3%), Tatars (28.4%) and molecule to produce a more hydrophilic oxidized product Bashkirs (21.9%). This region since ancient times was the scene and water molecule. CYPs perform two important functions of intense ethnic and cultural interactions of ethnic groups of in mammals: they are involved in metabolizing endogenous li- different origins. The current population of the Republic of pophilic substrates, such as steroids, arachidonates, and reti- Bashkortostan is extremely heterogeneous in its ethnic com- noids, and in transforming exogenous compounds. CYPs play position, linguistic and anthropological background (6). The a role in the activation of many procarcinogens (1, 2). study of autosomal DNA markers showed the presence in the Enzymes of the CYP1, CYP2, and CYP3 families are in- gene pool of peoples of Bashkortostan a significant proportion volved in metabolizing exogenous substrates, while members of Caucasoid traits -50 to 90%. Thus, caught at the border be- of other families are involved in the metabolism of endog- tween Europe and Asia, these peoples have preserved traces enous compounds such as vitamin D, retinoic acid, choles- of the mixing of two races, -one from the East, and another- terol and steroid hormones. Expression of the CYPs genes is from the West (7). In addition, it was found that the similarity regulated via several pathways. Inducible transcription is acti- of language plays a smaller role than the geographical prox- vated via a ligand-specific receptor, while constitutive expres- imity of populations. If, for example, people from the Russian Address for Correspondence: Dr. Gülnaz Korytina, Institute of Biochemistry and Genetics, Genomics, Ufa, Russian Federation E-mail: [email protected] Balkan Med J Korytina et al. 2012; 29: 252-60 Cytochrome P450 Genes in Russian Ethnic Groups 253 Ryazan and Kursk regions have only 2-3% of Mongoloid types procedure, gels were stained with 0.1 μg/mL ethidium bro- mtDNA, while the Russians who live on the border between mide for 15 min and photographed in transmitted UV light. Europe and Asia, have 10-12%. This is due to their mixing with Alleles were identified against a marker 100 bp DNA ladder the Turkic peoples in the South Ural region (8). Fermentas (Lithuania). Activity of enzymes, as well as the rate of the metabolic processes in the human body and, consequently, frequency of Statistical analysis the incidence for pathological diseases in the range of differ- Allele and genotype frequencies of the polymorphisms, ent populations vary substantially among them. This variability as well as errors, and confidence intervals were calculated in not only accounts for different environmental and social con- the Statistica v.6.0 program (www.statistica.com StatSoft ditions of the population, lifestyle and diet, but importantly, Inc., USA). Genotype frequency distributions were tested for the genetic background which causes variability in metabolic agreement with the Hardy-Weinberg equilibrium performing parameters. It follows that the pathogenetic relationships be- χ2 test using electronic calculator [http://www.genes.org.uk/ tween some genetic characteristics with individual response to software/hardy-weinberg.html]. CYP1A1 and CYP1A2 haplo- environmental factors can be detected only when the analysis type frequencies, and the values of normalized linkage disequi- includes consideration of specific population characteristics of librium coefficient (Lewontin’s coefficient),D ’, were computed study groups, particularly ethnic heterogeneity. using the expectation maximization algorithm and maximum The purpose of the present study was to investigate the likelihood method with the Haploview 4.2 (10). Differences in prevalence of the most common allelic variants of CYP1A1, allele, genotype and haplotype frequencies distributions be- CYP1A2, CYP1B1, CYP2C9, CYP2E1, CYP2F1, CYP2J2, and tween the ethnic groups were tested for significance by the CYP2S1 in a representative sample of the three ethnic groups χ2 test using the Statistica v. 6.0 programs (www.statistica. (Russians, Tatars and Bashkirs) from the Republic of Bashkor- com StatSoft Inc., USA) and Haploview 4.2 (10). tostan (Russia), and comparing the results with existing data published for other populations. Results Material and Methods Polymorphic variants of the CYPs genes were examined in three ethnic groups residing in the Republic of Bashkorto- DNA samples stan. Genotype frequencies distributions of the CYPs genes The total number of 742 DNA samples of healthy unrelated in all ethnic groups were examined for Hardy-Weinberg individuals, representatives of three ethnic groups, historically proportions. Statistical analysis showed that the genotype dispersed over the territory of the Republic of Bashkortostan frequencies of the CYPs polymorphism do not deviate from (South Ural Region of Russia) have been analyzed in this study. the Hardy-Weinberg proportions in all the considered ethnic There were 319 individuals classified as Russians, 279 Tatars, groups (Russians, Tatars and Bashkirs). Observed counts and and 144 Bashkirs. frequencies of the variant genotypes, alleles and halpotypes Prior to implementation, the present study was approved of the CYP1A1, CYP1A2, CYP1B1, CYP2C9, CYP2E1, CYP2F1, by the Independent Ethics Committee (IEC) of the Institute of CYP2J2 and CYP2S1 are shown in Table 2, 3 and 4. Biochemistry and Genetics, Ufa Scientific Centre of Russian Academy of Sciences, Ufa, Russia. Blood samples were col- CYP1A1 lected during research expeditions in 2004-2008. Ethnic origin Significant interethnic differences were found for the dis- (up to the third generation) was derived by direct interviews tribution of the CYP1A1 polymorphism rs1048943, 2454A>G with examined persons. Peripheral blood samples were col- (χ2=14.466, df=4, p=0.006 and χ2=10.03, df=2, p=0.007, for lected into EDTA tubes and stored at -20oC until DNA isola- genotype and allele, respectively) (Table 2, 3). For Russians tion. Genomic DNA was isolated from white blood cells (10 and Tatars, the genotype and allele frequencies distributions mL) by a standard procedure of phenol–chloroform extraction were similar (p=0.49 and p=0.302,