Electrotypes and formal genetics of red cell glutathione peroxidase (GPX1) in the Djuka of Surinam.

Samples of venous blood from 239 male and 476 female adults including 41 pairs of parents and 123 of their children belonging to a Surinam population called the Djuka or Bush Negroes of West African origin were screened for electrophoretic variants of red cell glutathione peroxidase (GPX1) in Cellogel. The results confirmed an earlier hypothesis that at least a part of the GPX1 variation mainly, if not exclusively, observed in the Africans and people of African origin living elsewhere, is determined by two codominant alleles (called GPX1*1 and GPX1*2), at an autosomal locus. The frequency of GPX1*2 allele in the Djuka was estimated to be .054. A rare variant provisionally designed as GPX1 Djuka (thought to be a heterozygote due to a third allele called GPX1*3 and the GPX1*1) was found in two apparently unrelated individuals. Catalytically, the product of GPX1*2 appears to be about twice more active than that of GPX1*1. For heuristic purposes, it was proposed and discussed that GPX1*2 is a South-Saharan African allele and is amenable for natural selection.     

<Emphasis Type="Italic">CAT</Emphasis> C-262T and <Emphasis Type="Italic">GPX1</Emphasis> Pro198Leu polymorphisms in a Turkish population

Oxidative stress is believed to play an important role in the pathogenesis of considerable number of complex diseases. The antioxidant enzymes catalase (CAT) and glutathione peroxidase (GPX) are important components of cell defense against oxidative stress, and polymorphisms in the genes which regulate their expression may contribute to differences in susceptibility of individuals to oxidative damage caused by reactive oxygen species. The aim of this study was to assess the distribution of CAT C-262T and GPX1 Pro198Leu genotypic variants in a Turkish population. Genotyping analyses of CAT and GPX1 were conducted in 250 unrelated, healthy volunteers by the PCR-RFLP assay. The allele frequencies were 0.784 (C) and 0.216 (T) for CAT and 0.636 (C) and 0.364 (T) for GPX1 Pro198Leu. The genotype frequencies were 0.632 (CC), 0.304 (CT), and 0.064 (TT) for CAT and 0.416 (CC), 0.44 (CT), and 0.144 (TT) for GPX1 Pro198Leu. The genotype frequencies did not deviate from Hardy–Weinberg equilibrium. The results are compared with those of other reported populations. They showed marked ethnic group differences.     

Multiplex pyrosequencing method to determine CYP2C9*3, VKORC1*2, and CYP4F2*3 polymorphisms simultaneously: its application to a Korean population and comparisons with other ethnic groups

Warfarin is an anticoagulant that is difficult to administer because of the wide variation in dose requirements to achieve a therapeutic effect. CYP2C9, VKROC1, and CYP4F2 play important roles in warfarin metabolism, and their genetic polymorphisms are related to the variability in dose determination. In this study we describe a new multiplex pyrosequencing method to identify CYP2C9*3 (rs1057910), VKORC1*2 (rs9923231), and CYP4F2*3 (rs2108661) simultaneously. A multiplex pyrosequencing method to simultaneously detect CYP2C9*3, VKORC1*2, and CYP4F2*3 alleles was designed. We assessed the allele frequencies of the polymorphisms in 250 Korean subjects using the multiplex pyrosequencing method. The results showed 100 % concordance between single and multiplex pyrosequencing methods, and the polymorphisms identified by pyrosequencing were also validated with the direct sequencing method. The allele frequencies of these polymorphisms in this population were as follows: 0.040 for CYP2C9*3, 0.918 for VKORC1*2, and 0.416 for CYP4F2*3. Although the allele frequencies of the CYP2C9*3 and VKROC1*2 were comparable to those in Japanese and Chinese populations, their frequencies in this Korean population differed from those in other ethnic groups; the CYP4F2*3 frequency was the highest among other ethnic populations including Chinese and Japanese populations. The pyrosequencing methods developed were rapid and reliable for detecting CYP2C9*3, VKORC1*2, and CYP4F2*3. Large ethnic differences in the frequency of these genetic polymorphisms were noted among ethnic groups. CYP4F2*3 exhibited its highest allele frequency among other ethnic populations compared to that in a Korean population.     

Allele frequency distribution of CYP2C9*2 and CYP2C9*3 polymorphisms in six Mexican populations

Allele frequency differences of functional CYP2C9 polymorphisms are responsible for some of the variation in drug response observed in human populations. The most relevant CYP2C9 functional variants are CYP2C9*2 (rs1799853) and CYP2C9*3 (rs1057910). These polymorphisms show variation in allele frequencies among different population groups. The present study aimed to analyze these polymorphisms in 947 Mexican-Mestizo from Mexico City and 483 individuals from five indigenous Mexican populations: Nahua, Teenek, Tarahumara, Purepecha and Huichol. The CYP2C9*2 allele frequencies in the Mestizo, Nahua and Teenek populations were 0.051, 0.007 and 0.005, respectively. As for CYP2C9*3, the allelic frequencies in the Mestizo, Nahua and Teenek populations were 0.04, 0.005 and 0.005, respectively. The CYP2C9*2 and CYP2C9*3 alleles were not observed in the Tarahumara, Purepecha and Huichol populations. These findings are in agreement with previous studies reporting very low allele frequencies for these polymorphisms in American Indigenous populations.     

Analysis of CYP2C9*2, CYP2C9*3 and VKORC1 ‐1639 G>A polymorphisms in a population from South‐Eastern Europe

The CYP2C9 enzyme metabolizes a wide range of relevant drugs, among which are oral anticoagulants. VKORC1 is the pharmacodynamic target of the oral anticoagulants. The genetic polymorphisms CYP2C9*2, CYP2C9*3 and VKORC1 ‐1639 G>A are the major determinants of the inter‐individual variability in the dosage requirements of oral anticoagulants. This study provides a first evaluation of these 3 polymorphisms in a Romanian population. A total of 332 Romanian individuals were genotyped for the CYP2C9*2, CYP2C9*3 and VKORC1 ‐1639 G>A polymorphisms using the PCR‐RFLP technique. Sixty‐two individuals (18.7%) were heterozygous for CYP2C9*2, whereas 47 individuals (14.1%) were heterozygous for CYP2C9*3. Fourteen individuals (4.2%) had a CYP2C9*2 homozygous, CYP2C9*3 homozygous or CYP2C9*2/CYP2C9*3 compound heterozygous genotype. These individuals are predicted to have the lowest CYP2C9 enzymatic activity. The allele frequencies of the CYP2C9*2 and CYP2C9*3 polymorphisms were 11.3% and 9.3% respectively. For the VKORC1 ‐1639 G>A polymorphism, there were 170 heterozygotes (51.2%) and 55 (16.6%) homozygotes for the A allele. The frequency of the A allele was 42.2%. Overall, the distribution of the CYP2C9*2, CYP2C9*3 and VKORC1 ‐1639 G>A polymorphisms observed in our cohort is in accordance with other Caucasian populations. A large number of Romanians are expected to harbour at least one CYP2C9 variant allele and/or one VKORC1 ‐1639 G>A allele. This frequency has major implications in the pharmacogenomics of oral anticoagulants in Romanians.     

Red cell glutathione peroxidase (GPX1) variation in Afro-Jamaican,Asiatic Indian,and Dutch populations

Summary A Cellogel procedure for screening the electrophoretic variants of the human red cell glutathione peroxidase (GPX1) was described. Three hundred and ninety eight Dutch persons living in various parts of The Netherlands, 385 individuals born in various states of India, and 72 Jamaicans of African origin livig in Birmingham, UK, were screened for GPX1 variants. The Dutch were monomorphic, while one Afro-Jamaican female and two males and one female of the 116 Punjabis were found to be variants indistinguishable from each other in their pattern of electrophoresis. The clear five banded pattern of the variant indicated that the subunit structure of the human red cell glutathione peroxidase is most probably a tetramer and suggested that the variant is the expression of a heterozygote due to alleles at an autosomal locus. The corresponding phenotype was designated tentatively as GPX1 2-1 and the alleles as GPX1 ^*1 and GPX1 ^*2 respectively. The variant 2-1 was found to be identical to the Thomas variant described by Beutler and West (1974). Thus so far, in addition to the Afro-Americans and Ashkenazi Jews (Beutler et al. 1974), the Punjabis of the Indian subcontinent (this report) were found to exhibit the GPX1 polymorphism due to the GPX1 ^*2 allele. The data discussed in this paper (which included unpublished observations on several African and non-African populations) suggest that the GPX1 ^*2 allele is originally an African variant and hint that the present day Punjabis of Indian subcontinent, like Ashkenazi Jews, are predominantly of Mediterranean origin with some proportion of African ancestry (Mourant et al. 1976).     

Characterization of pharmacogenetically relevant CYP2D6 and ABCB1 gene polymorphisms in a Portuguese population sample

Differences in metabolism of drugs can lead to severe toxicity or therapeutic failure. In addition to cytochrome P450 2D6, which plays a critical role in drug metabolism, ABCB1 encoded P‐glycoprotein (PGP) is also an important determinant in drug bioavailability. The genes encoding these molecules are highly variable among populations and, given their clinical importance in drug therapy, determining CYP2D6 and ABCB1 allele frequencies in specific populations is very important for useful application in clinical settings. In this study the frequency of the pharmacologically relevant CYP2D6*3, *4, *5, *6 allelic variants and gene duplication, and ABCB1 C1236T and C3435T gene polymorphisms and their haplotypes was determined in a population sample of 100 Portuguese healthy subjects. CYP2D6 allele frequencies were 1.4% (*3), 13.3% (*4), 2.8% (*5), 1.8% (*6) and 6.1% (gene duplication), with 5% of the individuals classified as PM and 8.4% as UM. The frequencies obtained for the non‐functional alleles and for the CYP2D6 gene duplication are in agreement with other South European populations, and reinforce the previously suggested south/north gradient of CYP2D6 duplications. Allelic frequencies for the ABCB1 polymorphisms were 52% (3435C) and 54% (1236C) and the most common haplotype (1236C‐3435C) occurred with a frequency of 45.5%. Although allele and haplotype frequency data for ABCB1 in Southern Europe is limited, some discrepancies were found with other European populations, with possible therapeutic implications for PGP substrate drugs. Copyright © 2009 John Wiley & Sons, Ltd.     

The prevalence of VKORC1 1639 G>A and CYP2C9*2*3 genotypes in patients that requiring anticoagulant therapy in Turkish population

The aim was to investigate the prevalence of VKORC1 and CYP2C9 genotypes in patients requiring anticoagulant therapy in two different region’s populations of Turkey. The recent cohort included 292 patients that needed anticoagulant therapy, and who had a history of deep vein thrombosis and/or pulmonary artery thromboembolism. Genomic DNA was isolated from peripheral blood samples and the StripAssay reverse hybridization or Real Time PCR technique was used for genotype analysis. Genotypes for CYP2C9 were detected as follows: 165 (56.5?%) for CYP2C9*1/*1, 67 (23.0?%) for CYP2C9*1/*2, 25 (8.6?%) for CYP2C9*1/*3, 9 (3.0?%) for CYP2C9*2/*2, 21 (7.2?%) for CYP2C9*2/*3, 5(1.7?%) for CYP2C9*3/*3 for CYP2C9 and the allele frequencies were: 0.723 for allele*1, 0.182 for allele*2 and 0.095 for allele*3 respectively. Genotypes for VKORC1 were detected as follows: 64 (21.9?%) for GG, 220 (75.4?%) for GA and 8 (2.7?%) for AA alleles. The G allele frequency was detected as 0.596, and the A allele frequency was 0.404. The VKORC1 1639 G>A and CYP2C9 mutation prevalence and allele frequency of the current results from two different populations (Sivas and Canakkale) showed similarly very variable profiles when compared to the other results from the Turkish population.     

Cytochrome P4501A1 polymorphisms in the Amerindian and Mestizo populations of Mexico

Several polymorphisms in the CYP1A1 locus have been identified and their genotypes appear to exhibit population frequencies that depend on ethnicity. We studied two CYP1A1 polymorphic sites (position 4889 and 6235) in a group of 212 unrelated healthy individuals belonging to three different Mexican populations (106 Mexican Mestizos, 52 Teenek and 54 Mayos). Comparison among Mexican populations showed increased frequency of the *Ile allele (A on position 4889) in Mexican Mestizos when compared to Amerindians (p < 0.05). The analysis of position 6235 showed increased frequencies of *m2 (C in this position) allele in Teenek when compared to Mestizos and Mayos (p < 0.05) and of *m2/*m2 genotype when compared to Mestizos (p < 0.05). Amerindian populations (from Mexico and South America) presented the lowest frequencies of *Ile (position 4889) and *m1 (position 6235) alleles, however these frequencies vary according to the ethnic group studied. Mexican Amerindian groups together with other South Amerindian populations showed the highest frequencies for *Val at position 4889 and the *m2 allele at position 6235. The present study corroborates the high frequencies of*Val and *m2 alleles in the Amerindian populations and detects some differences between Mexican populations that correlate with linguistic differences. Our data could be helpful in understanding the distribution of these polymorphisms and in clarifying their roles as genetic and evolution markers in Amerindian populations.     

Inter and intra-ethnic differences in the distribution of the molecular variants of TPMT, UGT1A1 and MDR1 genes in the South Indian population

Molecular variants of polymorphic drug metabolizing enzymes and drug transporters are attributed to differences in individual's therapeutic response and drug toxicity in different populations. We sought to determine the genotype and allele frequencies of polymorphisms for major phase II drug-metabolizing enzymes (TPMT, UGT1A1) and drug transporter (MDR1) in South Indians. Allelic variants of TPMT (*2,*3A,*3B,*3C & *8), UGT1A1 (TA)6>7 and MDR1 (2677G>T/A & 3435C>T) were evaluated in 450-608 healthy South Indian subjects. Genomic DNA was extracted by phenol-chloroform method and genotype was determined by PCR-RFLP, qRT-PCR, allele specific PCR, direct sequencing and SNaPshot techniques. The frequency distributions of TPMT, UGT1A1 and MDR1 gene polymorphisms were compared between the individual 4 South Indian populations viz., Tamilian, Kannadiga, Andhrite and Keralite. The combined frequency distribution of the South Indian populations together, was also compared with that of other major populations. The allele frequencies of TPMT*3C, UGT1A1 (TA)7, MDR1 2677T, 2677A and 3435T were 1.2, 39.8, 60.3, 3.7, and 61.6% respectively. The other variant alleles such as TPMT*2, *3A, *3B and *8 were not identified in the South Indian population. Sub-population analysis showed that the distribution of UGT1A1 (TA)6>7 and MDR1 allelic variants differed between the four ethnic groups. However, the frequencies of TPMT*3C allele were similar in the four South Indian populations. The distribution of TPMT, UGT1A1 and MDR1 gene polymorphisms of the South Indian population was significantly different from other populations.     

Polymorphisms of CYP1a1, CYP2e1, GSTM1, GSTT1, and TP53 genes in Amerindians

Polymorphisms at the TP53, cytochrome P‐450 (CYP), and glutathione S‐transferase (GST) genes are related to cancer susceptibility and present high diversity in allele frequencies among ethnic groups. This study concerns the CYP2E1, GSTM1, and GSTT1 polymorphisms in seven Amerindian populations (Xavante, Guarani, Aché, Wai Wai, Zoró, Surui, and Gavião). Polymorphic sites at CYP1A1 and TP53 were also studied in the Aché and Guarani tribes and compared with previous results about these systems already obtained in the other populations. The CYP2E1*5B haplotype showed, respectively, the highest and the lowest frequencies already observed in human groups. High frequencies of CYP1A1*2A and CYP1A1*2C alleles and mostly low values of GSTM1*0/*0 and GSTT1*0/*0 genotypes were observed. These data may be interpreted as being due to genetic drift or selection for these high‐frequency CYP1A1 alleles and against GST null genotypes during America's colonization. Intrapopulation diversity varied from 0.19 (Guarani) to 0.38 (Surui), and 90% of the total diversity was due to the variability within populations. The relationships between these Amerindians and with other ethnic groups were evaluated based on D_A distances and the neighbor‐joining method. Low correlation was observed between genetic relationships and geographic distances or linguistic groups. In the TP53 comparison with other ethnic groups, Amerindians clustered together and then joined Chinese populations. The cluster analysis seems to indicate that the Aché tribe might descend from a Gê group that could have first colonized that Paraguayan region, but had also assimilated some amount of the Guarani gene pool, maybe through intertribal admixture. Am J Phys Anthropol 119:249–256, 2002. © 2002 Wiley‐Liss, Inc.     

High prevalence of CYP2C19*2 allele in Roma samples: study on Roma and Hungarian population samples with review of the literature

The purpose of our study was to characterise the CYP2C19*2 and CYP2C19*3 alleles in healthy Roma and Hungarian populations. DNA of 500 Roma and 370 Hungarian subjects were genotyped for CYP2C19*2 (G681A, rs4244285) and CYP2C19*3 (G636A, rs4986893) by PCR–RFLP assay and direct sequencing. Significant differences were found comparing the Roma and Hungarian populations in CYP2C19 681 GG (63.6 vs. 75.9 %), GA (31.8 vs. 23.0 %), AA (4.6 vs. 1.1 %), GA+AA (36.4 vs. 24.1 %) and A allele frequencies (0.205 vs. 0.125) (p < 0.004). Striking differences were found between Roma and Hungarian samples in CYP2C19*1 (79.5 vs. 87.4 %) and CYP2C19*2 (20.5 vs. 12.6 %) alleles, respectively (p < 0.001). None of the subjects was found to carry the CYP2C19*3 allele. Frequencies of the intermedier metabolizer phenotype defined by the *1/*2 genotype (0.318 vs. 0.230, p < 0.005) and poor metabolizer predicted by the *2/*2 genotype (0.046 vs. 0.011, p < 0.005) was significantly higher in Roma than in Hungarians, respectively. Genotype distribution of the Roma population was similar to those of the population of North India, however, a major difference was found in the frequency of the CYP2C19*2 allele, which is likely a result of admixture with European lineages. In conclusion, the frequencies of the CYP2C19 alleles, genotypes and corresponding extensive, intermediate and poor metabolizer phenotypes studied here in the Hungarian population are similar to those of other European Caucasian populations, but display clear differences when compared to the Roma population.     

High frequency of CYP1A1*2C allele in Brazilian populations

The genetic variability of the CYP1A1 I462V polymorphism (CYP1A1*2C) was investigated in four Brazilian populations: three groups of African descent and one group of European descent. The CYP1A1 polymorphism was analyzed by two different procedures, first by the allele-specific polymerase chain reaction (PCR) method and then by the PCR-restricted fragment length polymorphism (PCR-RFLP) method before digestion with BsrDI. The frequency of CYP1A1 *2C was 11% in Brazilians of European descent, a frequency that is slightly higher but not statistically different from that observed in European populations. In Brazilians of African ancestry this value was very high (12% to 15%). This allele was not observed in the only two African populations investigated thus far. By themselves, the two factors of interethnic admixture (with populations of European descent and/or Amerindian populations) and genetic drift cannot explain the high values observed here. Our findings suggest that the CYP1A1 *2C allele may possibly be present in Africa, but restricted to some ethnic groups not yet investigated. Environmental factors in South America might also have acted as selective factors increasing the CYP1A1 *2C gene frequency. Our data also suggest that the CYP1A1 *2C allele might possibly have originated in Africa.     

Effect of point substitutions in the <Emphasis Type="Italic">MnSOD,GPX1</Emphasis>, and <Emphasis Type="Italic">GSTP1</Emphasis> genes on the risk of familial and sporadic breast cancers in residents of Altai Krai

The frequencies of the polymorphic gene variants MnSOD Ala₉Val, GPX1 Pro₁₉₈Leu, and GSTP1 Ile₁₀₅Val were estimated in female residents of Altai krai with breast cancer. The frequency distributions of the genotypes for all genes studied in both patients and control subjects fit the Hardy-Weinberg equilibrium. The estimated frequencies of the genotypes for the studied genes in the control group did not differ from those earlier reported for Caucasoid women living in Europe. The T (rs1050450) allele of the GPX1 gene was demonstrated to protect against sporadic breast cancer (OR = 0.74 (95% CI = 0.58−0.94), p = 0.012). Carriers of the genotype combination MnSOD CC + GPX1 CC were found to have a 1.6 times higher risk of sporadic breast cancer compared to the control group (OR = 1.59 (1.05−2.41), p = 0.0258). The polymorphic loci GSTP1 (rs1695) and MnSOD (rs4880) were not found to be significantly associated with the risk of familial or sporadic breast cancer.     

Frequencies of the GPXT1 (or GPX*2(1) and CA2II alleles in some Congo populations

Genetic polymorphism of red cell enzyme glutathione peroxidase (GPX1) and carbonic anhydrase (CAII) was investigated in four Congo populations (Beti Bantus, North Bateke and South Bateke Bantus and Babenga Pygmies). All show a polymorphic frequency of the GPXT1 and CA2II alleles, though with a certain variability of values.     

Transferrin C subtypes and ethnic heterogeneity in Sweden

Transferrin (TF) C subtypes were studied in Swedish Lapps (Saami) and in Swedes from northern, central and southern Sweden, and the allele frequencies were compared with those in other European populations. The Swedish Lapps were found to have the lowest frequency of the TF*C3 allele (1-2%) so far observed in Europe. Most European populations have TF*C3 allele frequencies between 5 and 7%. Finns differ by having high TF*C3 frequencies (13-14%). The relatively high TF*C3 frequencies found in northeastern Sweden (13%) and in central Sweden (9%) are most likely due to eastern influence. Unlike other genetic markers of eastern influence (e.g. TF*DCHI), which are of Asiatic Mongoloid origin, TF*C3 appears to originate from Finno-Ugric populations.     

Allele and genotype frequencies of the polymorphic cytochrome P450 genes (CYP1A1, CYP3A4, CYP3A5, CYP2C9 and CYP2C19) in the Jordanian population

Drug metabolizing enzymes participate in the neutralizing of xenobiotics and biotransformation of drugs. Human cytochrome P450, particularly CYP1A1, CYP2C9, CYP2C19, CYP3A4 and CYP3A5, play an important role in drug metabolism. The genes encoding the CYP enzymes are polymorphic, and extensive data have shown that certain alleles confer reduced enzymatic function. The goal of this study was to determine the frequencies of important allelic variants of CYP1A1, CYP2C9, CYP2C19, CYP3A4 and CYP3A5 in the Jordanian population and compare them with the frequency in other ethnic groups. Genotyping of CYP1A1(m1 and m2), CYP2C9 (*2 and *3), CYP2C19 (*2 and *3), CYP3A4*5, CYP3A5 (*3 and *6), was carried out on Jordanian subjects. Different variants allele were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). CYP1A1 allele frequencies in 290 subjects were 0.764 for CYP1A1*1, 0.165 for CYP1A1*2A and 0.071 for CYP1A1*2C. CYP2C9 allele frequencies in 263 subjects were 0.797 for CYP2C9*1, 0.135 for CYP2C9*2 and 0.068 for CYP2C9*3. For CYP2C19, the frequencies of the wild type (CYP2C19*1) and the nonfunctional (*2 and *3) alleles were 0.877, 0.123 and 0, respectively. Five subjects (3.16?%) were homozygous for *2/*2. Regarding CYP3A4*1B, only 12 subjects out of 173 subjects (6.9?%) were heterozygote with none were mutant for this polymorphism. With respect to CYP3A5, 229 were analyzed, frequencies of CYP3A5*1,*3 and *6 were 0.071, 0.925 and 0.0022, respectively. Comparing our data with that obtained in several Caucasian, African-American and Asian populations, Jordanians are most similar to Caucasians with regard to allelic frequencies of the tested variants of CYP1A1, CYP2C9, CYP2C19, CYP3A4 and CYP3A5.     

Genetic variants of the paraoxonases (PON1 and PON2) in the Chilean population

We estimated the frequencies of PON1 and PON2 variants (linked genes) in two hospital samples taken from the northern (San José Hospital, SJH) and eastern (Clínica Las Condes, CLC) parts of Santiago, Chile, using the polymerase chain reaction followed by restriction endonuclease digestion. The two hospital samples have different degrees of Amerindian admixture (SJH, 34.5%; CLC, 15.9%), which is reflected in the observed frequencies of the PON1 *B allele (SJH, 43.1%; CLC, 33.7%) and the PON2*S allele (SJH, 86.3%; CLC, 77.6%); both allele frequencies are significantly different between samples. The frequencies of the combined PON1-PON2 genotypes *A/*B-*C/*C, *A/*B-*S/*S, and *B/*B-*S/*S and of the haplotypes PON*A,C and PON*B,S were significantly different between the SJH and CLC groups. None of the genotype frequencies deviated significantly from those predicted by the Hardy-Weinberg equation. No linkage disequilibrium was found between the PON1 alleles and any of the PON2 alleles in either group (all p > 0.05). In our samples 38.52% (SJH) and 26.25% (CLC) of chromosomes must have the haplotype PON*B,S, presumed to be related to the risk of coronary artery disease. Twenty-four of 193 (12.4%) SJH individuals and 7 of 122 (5.7%) CLC individuals were homozygotes for this haplotype. Finally, our data indicate ethnic-group-dependent genetic differences in the vulnerability to toxic organophosphorus.     

Polymorphism of CYP1A1 and CYP2D6 genes in tundra nentses and European populations of western Siberia

Data on the first examination of the CYP1A1 and CYP2D6 genes' polymorphism in the populations of Tundra Nentsis (Yamalo-Nenetskii Autonomous District) and migrant population of Western Siberia (Novosibirsk oblast and Altaiskii krai) are presented. The frequency of the 2D6*4 mutant allele in Tundra Nentsis, characterized by a two-component Caucasoid and Mongoloid origin, was shown to be intermediate in Caucasoid and Mongoloid populations. The frequencies of the 2D6*4 and 1A1Val* mutant alleles across migrant inhabitants of Western Siberia (Caucasoid populations) were similar to that reported for the Caucasoid populations overall. Distribution of the CYP1A1 genotypes (Ile/Ile, Ile/Val*, and Val*/Val*) in Tundra Nentsis was similar to that found in Mongoloid groups. However, the frequency of the 1A1Val* allele in Tundra Nentsis was 1.5 times higher than that in the Southern Mongoloid populations (Chinese, Koreans, and Japanese).     

The frequency and distribution of thiopurine S-methyltransferase alleles in south Iranian population

Thiopurine methyltransferase (TPMT) catalyzes the S-methylation of thiopurine drugs such as 6-mercaptopurine, 6-thioguanine, and azathiopurine. Variability in TPMT activity is mainly due to genetic polymorphism. The frequency of the four allelic variants of the TPMT gene, TPMT*2 (G238C), TPMT*3A (G460A and A719G), TPMT*3B (G460A) and TPMT*3C (A719G) were determined in an Iranian population from south of Iran (n = 500), using polymerase chain reaction (PCR)-RFLP and allele-specific PCR-based assays. Four hundred seventy four persons (94.8%) were homozygous for the wild type allele (TPMT*1/*1) and twenty five people were TPMT*1/*3C (5%). One patient was found to be heterozygous in terms TPMT*1 and *2 alleles with genotype of TPMT*1/*2 (0.2%). None of the participants had both defective alleles. The TPMT*3C and *2 were the only variant alleles observed in this population. The total frequency of variant alleles was 2.6% and the wild type allele frequency was 97.4%. The TPMT*3B and *3A alleles were not detected. Distributions of TPMT genotype and allele frequency in Iranian populations are different from the genetic profile found among Caucasian or Asian populations. Our findings also revealed inter-ethnic differences in TPMT frequencies between different parts of Iran. This view may help clinicians to choose an appropriate strategy for thiopurine drugs and reduce adverse drug reactions such as bone marrow suppression.