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PubMed2004

Association between ENOS gene polymorphism and cardiovascular events in nondiabetic hemodialysis patients: a prospective study.

BACKGROUND: Synthesis of nitric oxide by endothelial nitric oxide synthase (ENOS) plays a key role in the atherosclerotic process. Several polymorphisms of the gene encoding ENOS are now known and have been investigated with respect to their influence on cardiovascular disease risk in the general population. The authors prospectively investigated whether ENOS gene polymorphisms determined the risk of cardiovascular complications in a cohort of hemodialysis patients. METHODS: A total of 335 nondiabetic hemodialysis patients were genotyped for 3 ENOS polymorphisms (T-786-->C, intron 4, and Glu298Asp polymorphism) and were followed up prospectively for a mean of 44.2 +/- 9.0 months. The end-points of the study were major cardiac, cerebrovascular, or peripheral vascular events. RESULTS: Two ENOS polymorphisms were associated with cardiovascular events: a T to C substitution at position -786 of the promoter and a deletion-insertion in intron 4 (the a allele having 4 repeats of a consensus sequence and the b allele having 5 repeats). A total of 84 subjects were -786C carriers (CC+TC), and 15 (18%) suffered from cardiovascular events compared with only 13 of 251 TT patients (5%). The relative risk of cardiovascular events was higher for -786C carriers compared with noncarriers (relative risk: 2.05, P = 0.0003). It was also higher for a allele carriers (intron 4 polymorphism) compared with noncarriers (relative risk: 1.97, P = 0.0005). CONCLUSION: T-786-->C polymorphism and intron 4 polymorphism, but not Glu298Asp polymorphism, of the ENOS gene can influence the risk of cardiovascular events in Japanese nondiabetic hemodialysis patients.

Adult↗

PubMed2004

IL1B and IL1RN polymorphic genes and Helicobacter pylori cagA strains decrease the risk of reflux esophagitis.

BACKGROUND & AIMS: Proinflammatory interleukin (IL)-1 gene polymorphisms associated with high levels of IL-1beta activity increase the risk for hypochlorhydria and distal gastric carcinoma. The aim of this study was to evaluate whether carriers of these polymorphic genes are protected against gastroesophageal reflux disease (GERD). TNFA-308 polymorphisms were also studied. METHODS: We prospectively evaluated 385 patients without gastric cancer and peptic ulcer. Of these patients, 383 (98 with GERD and 285 controls) were successfully genotyped for all cytokines studied. The cagA status of Helicobacter pylori isolates was determined by polymerase chain reaction (PCR). IL1B-511/-31, IL1RN, and TNFA-308 polymorphisms were genotyped by PCR, PCR/restriction fragment length polymorphism, or PCR/confronting 2-pair primers. Histologic gastritis was assessed according to the updated Sydney system. The role of the proinflammatory cytokine genotypes in the genesis of GERD was evaluated before and after stratification by H. pylori status in logistic regression models controlling for confounding factors. RESULTS: IL1B-31 (a near-complete linkage disequilibrium between polymorphism at -31 and -511 was found) and IL1RN*2 allele polymorphisms were associated with GERD. After stratification, in the group of H. pylori-positive patients, cagA-positive status, IL1B-31 polymorphic alleles, IL1RN*2 alleles, and the degree of corpus gastritis were negatively associated with GERD. In the H. pylori-negative group, IL1B-31C/C genotype was inversely associated with GERD even after adjustment for age and sex. CONCLUSIONS: This study provides evidence supporting the independent protective role of cagA-positive H. pylori status and IL1B and ILRN allele polymorphisms against GERD.

Adult↗

PubMed1994

Inference of human evolution through cladistic analysis of nuclear DNA restriction polymorphisms.

Testing of nuclear DNA polymorphisms in human populations has been extended to closely related primates. For many polymorphisms, one allele is shared by two or more species: such shared alleles are likely to be ancestral and provide insight not only into the relationships among the primates but also into the evolutionary history of modern humans. Humans from among eight worldwide populations share an allele with chimpanzees for 62 out of 79 polymorphisms examined. Frequencies of these ancestral alleles strengthen the conclusion that the earliest major separation of modern humans was between Africans and non-Africans. The average time since mutation of the ancestral alleles producing the current set of polymorphisms is estimated to be 700,000 years. While differences among ancestral allele frequencies in human populations suggest that natural selection may have played a role in the evolution of a subset of these polymorphisms, simulations indicate that a European bias in the ascertainment of polymorphisms may be at least partially responsible for observed differences. Simulations also suggest that observed heterozygosity levels in African populations, for classical polymorphisms and restriction fragment length polymorphisms, are artificially low due to the same bias. Observed patterns of mean heterozygosity and mean ancestral allele frequency provide support for the hypothesis that Europeans and northeast Asians are closely related. This work suggests that polymorphisms should be selected by testing a random sample of extant humans.

Alleles↗

PubMed1998

Persistence of neutral polymorphisms in Lake Victoria cichlid fish.

Phylogenetic trees for groups of closely related species often have different topologies, depending on the genes used. One explanation for the discordant topologies is the persistence of polymorphisms through the speciation phase, followed by differential fixation of alleles in the resulting species. The existence of transspecies polymorphisms has been documented for alleles maintained by balancing selection but not for neutral alleles. In the present study, transspecific persistence of neutral polymorphisms was tested in the endemic haplochromine species flock of Lake Victoria cichlid fish. Putative noncoding region polymorphisms were identified at four randomly selected nuclear loci and tested on a collection of 12 Lake Victoria species and their putative riverine ancestors. At all loci, the same polymorphism was found to be present in nearly all the tested species, both lacustrine and riverine. Different polymorphisms at these loci were found in cichlids of other East African lakes (Malawi and Tanganyika). The Lake Victoria polymorphisms must have therefore arisen after the flocks now inhabiting the three great lakes diverged from one another, but before the riverine ancestors of the Lake Victoria flock colonized the Lake. Calculations based on the mtDNA clock suggest that the polymorphisms have persisted for about 1.4 million years. To maintain neutral polymorphisms for such a long time, the population size must have remained large throughout the entire period.

Actins↗

PubMed2001

Genetic polymorphisms and chromosome damage.

Genetic polymorphisms that affect xenobiotic metabolism or cellular response to DNA damage can modulate individual sensitivity to genotoxins. Information on the effects of such polymorphisms on the level of chromosome damage may facilitate the identification of risk groups and increase the sensitivity of cytogenetic endpoints as biomarkers of genotoxic exposure and effect. Glutathione S-transferase M1 (GSTM1) is an important detoxification enzyme which, due to a homozygous gene deletion (null genotype), is lacking from about 50% of Caucasians. A higher level of DNA adducts and chromosome damage has been detected in lymphocytes of tobacco smokers and bus drivers who lack the GSTM1 gene. Other polymorphic glutathione S-transferases include GSTM3, GSTP1, and GSTT1. The GSTT1 null genotype (10-20% of Caucasians) has been associated with an increased "baseline" level of sister chromatid exchanges (SCEs) in lymphocytes. N-acetyltransferase 2 (NAT2), metabolizing xenobiotics with primary aromatic amine and hydrazine structures, is another important polymorphic phase II enzyme. Subjects having the NAT2 slow acetylator genotype appear to show an increased baseline frequency of lymphocyte CAs in the absence of identified environmental exposure. Besides human biomonitoring studies, genetic polymorphisms may be important in explaining individual variation in genotoxic response observed in genetic toxicology tests with human cells. Several studies have suggested that blood cultures from GSTT1 null and GSTM1 null individuals have increased in vitro sensitivity to various genotoxins. The best-known example is probably the diepoxybutane sensitivity of GSTT1 null donors. Recently discovered polymorphisms affecting DNA repair may be expected to be of special importance in modulating genotoxic effects; the first available studies have suggested that the exon 10 Arg399Gln polymorphism of XRCC1 gene (X-ray repair cross-complementing group 1) could affect individual genotoxic response. In conclusion, the genetic polymorphism of GSTM1 influences the frequency of chromosome damage in exposed humans, while that of GSTT1 and NAT2 affect the "baseline" level of such damage. Both GSTM1 and GSTT1 genotypes may shape the in vitro genotoxic response of human lymphocytes. The significance of DNA repair polymorphisms is presently unclear.

Chromosome Aberrations↗

PubMedDate not supplied

TNF-alpha promoter gene polymorphisms in Spanish children with persistent oligoarticular and systemic-onset juvenile idiopathic arthritis.

OBJECTIVE: To explore the possible association/s of the first reported tumour necrosis factor (TNF-alphaTNF-) alpha promoter gene polymorphisms -308, -238, -376 and -163 (G-->A) with systemic (SoJIA) and oligoarticular subtypes of juvenile idiopathic arthritis (JIA); and to test the association between these polymorphisms and the class I/class II HLA alleles in our population. METHODS: The patient group comprised 29 oligoarticular and 26 systemic Caucasian Spanish children with JIA; 68 healthy volunteers from the same ethnic group and geographical region served as controls. HLA alleles were determined using low-resolution polymerase chain reaction (PCR). TNF-alpha promoter gene polymorphisms were screened using PCR denaturing gradient gel electrophoresis (PCR-DGGE), followed, if positive, by restriction fragment length polymorphism (RFLP) analysis for identification. RESULTS: No statistical association was found between the four polymorphisms studied and JIA. However, the -308 G-->A polymorphism (TNF A2) tended to be more frequent in patients with SoJIA than in the oligoarticular group. TNF A2 was strongly associated with the extended haplotype A1B8DR3 (p = 0.003), and the tandem polymorphism -238/-376 in the presence of B18 and DR3. CONCLUSION: The TNF A2 allele was more frequent in SoJIA than in the oligoarticular group. TNF A2 can help to create a more inflammatory milieu in this JIA subtype, in combination with other polymorphisms involved in regulatory sequences of key molecules in the inflammatory response. The association of the -308 and -238/-376 polymorphisms with specific alleles of the HLA is reconfirmed.

Arthritis, Juvenile↗

PubMed2003

Relation of aromatase gene polymorphism and hormone replacement therapy to serum estradiol levels, bone mineral density, and fracture risk in early postmenopausal women.

BACKGROUND: After the menopause, estrogen synthesis from androgens and androgen precursors by aromatase is the main source of circulating estrogens. AIM: To evaluate whether aromatase gene (CYP19)polymorphism affects circulating estradiol (E2) levels, bone mineral density (BMD), BMD change or fracture risk. METHODS: A 5-year randomized hormone replacement therapy (HRT) trial on 331 early postmenopausal women (mean baseline age 52.7 +/- 2.3 years). The participants consisted of two treatment groups: the HRT group (n = 151) received a sequential combination of 2 mg estradiol valerate and 1 mg cyproterone acetate with or without vitamin D3, 100-300 IU + 93 mg calcium as lactate/day, and the non-HRT group (n = 180) received 93 mg calcium alone or in combination with vitamin D3, 100-300 IU/day for 5 years. BMD was measured from lumbar spine and proximal femur (DXA) before and after the 5-year trial. All new symptomatic, radiographically defined fractures were recorded during the follow-up. The polymorphism (intron 4 TTTA repeat) of CYP19 was evaluated after PCR amplification of the polymorphic site. CYP19 polymorphism was divided into three repeat groups: short (length of 7 or 8 in both alleles; n = 135), long (length of 11 or higher in both alleles; n = 47), and medium (rest of the values; n = 149). RESULTS: Of the baseline characteristics, only physical activity was associated with CYP19 polymorphism (P = 0.04) and a borderline significance was observed with previous fractures (P = 0.05). In the HRT or non-HRT groups, the 5-year serum E2 change was not associated with CYP19 polymorphism (P = 0.87 and 0.74, respectively). Further, the polymorphism did not influence the calculated annual changes of lumbar or femoral neck BMD during the 5-year follow-up in the HRT (P = 0.60 and 0.17, respectively) or non-HRT (P = 0.92 and 0.80, respectively) groups. In all, 28 women sustained 33 fractures during the follow-up. The CYP19 polymorphism was not significantly associated with fracture risk (P = 0.89 and 0.23 respectively; Cox proportional hazards model) in the HRT or non-HRT groups. CONCLUSIONS: CYP19 polymorphism was not associated with circulating E2 levels, BMD values, or fracture risk in these early postmenopausal Finnish women. If such an association exists in women, it may become apparent in older age groups.

Aromatase↗

PubMed2001

Lack of association of the renin-angiotensin system genes polymorphisms and left ventricular hypertrophy in hypertension.

OBJECTIVE: The aim of the present study was to determine if there is an association of different gene polymorphisms of renin-angiotensin system and left ventricular hypertrophy (LVH) in patients with essential hypertension (EH) in St Petersburg population. PATIENTS AND METHODS: We examined 156 patients (the mean age 49+/-8 years) with mild-to-moderate EH recruited from the general population of the outpatient clinic. Left ventricular mass was measured by echocardiography and left ventricular mass index (LVMI) was calculated. Subjects were genotyped for I/D polymorphism of the angiotensin-converting enzyme (ACE) gene, A1166C polymorphism of the AT1 receptor gene, M235T polymorphism of angiotensinogen gene and -6G/A polymorphism of its promoter region. RESULTS: Genotype distribution of the sample obeyed Hardy-Weinberg equilibrium and was comparable to that reported previously for hypertensive individuals. Groups of patients with II, ID and DD polymorphism of ACE gene did not differ significantly in their LVMI levels. Furthermore, neither ID ACE-gene polymorphism nor ATI-receptor gene and angiotensinogen gene polymorphism was associated with LVH. Additionally, no any significant gene-gene interactions were found to be associated with LVH in the group studied. CONCLUSIONS: In the light of these observations it seems reasonable to make a preliminary conclusion about lack of association between LVH and distinct polymorphisms of renin-angiotensin system genes in the population studied.

Adult↗

PubMedDate not supplied

XRCC1 Arg399Gln genetic polymorphism in a Turkish population.

Humans are routinely exposed to mutagenic and carcinogenic chemicals. These chemicals can form DNA adducts in vivo and thus lead to DNA damage. The integrity of most of the so-damaged DNAs is typically restored as a consequence of the action of certain DNA-repairing enzymes. In several DNA repair genes, polymorphisms may result in reduced repair capacity, which has been implicated as a risk factor for various types of cancer. XRCC1 is a base-excision repair protein that plays a central role in the repair of DNA base damage and strand breaks. Amongst the known genetic polymorphisms of the DNA-repair genes, X-ray repair cross-complementing groups 1 and 3 (XRCC1 and XRCC3) have been studied most commonly. Inconsistent results have been reported regarding the associations between the Arg399Gln (exon 10) polymorphism of XRCC1 and either functional significance or the risk of tobacco-associated cancers. The Gln allele of this polymorphism was associated with higher levels of DNA adducts. Therefore we genotyped one of the polymorphism of XRCC1, Gln allele. The frequency of the polymorphic alleles varies among populations, suggesting an ethnic distribution of genotypes. There has been no information on interindividual variability of Arg399Gln genotype in the Turkish population. Due to the association between the Arg399Gln polymorphism of XRCC1 and the risk of tobacco-associated cancers, we preferred to evaluate the allelic frequencies of Arg399Gln genotype than the other polymorphisms in XRCC1 gene in healthy Turkish population by polymerase chain reaction-restriction fragment polymorphism (PCR-RFLP) analysis to enable to show interindividual differences and compare to other populations.

Adult↗

PubMed2001

Human sensitivity to 1,3-butadiene: role of microsomal epoxide hydrolase polymorphisms.

1,3-Butadiene (BD) is a major commodity chemical used in the manufacture of synthetic rubber and various plastics and has been shown to be a potent animal carcinogen and a probable human carcinogen. The bioactivation of BD to reactive epoxides, and the balance between activation and detoxication of these reactive metabolites, is thought to play a critical role in the genotoxic and carcinogenic effects of BD. The detoxication of reactive BD metabolites involves enzymatic conjugation with glutathione by glutathione S-transferases (GSTs) and by hydrolysis, a reaction mediated by microsomal epoxide hydrolase (mEH). Since polymorphisms in genes of xenobiotic-metabolizing enzymes such as mEH may influence individual susceptibility to adverse health effects from BD exposure, we tested the hypothesis that the mEH Tyr113His polymorphism increases sensitivity to the genotoxic effects of BD in exposed workers. We used the autoradiographic hprt mutant lymphocyte assay as a biomarker of effect to identify genotoxicity associated with BD exposure in 49 workers from two styrene/butadiene polymer plants in Southeast Texas. Exposure to BD was assessed by collecting breathing zone air samples using passive badge dosimeters for three full 12 h work shifts 25, 20 and 14 days before blood was collected for genotyping and for the hprt assay. We genotyped the study participants for the Tyr113His polymorphism in the mEH gene and also for deletion polymorphisms in the glutathione S-transferase genes, GSTM1 and GSTT1, as potential biomarkers of susceptibility to BD. Our data indicate that the majority of the study subjects (67%) were exposed to very low levels of BD of <150 parts per billion (p.p.b.) time-weighted average (TWA). In some workers, however, we found levels of BD exposures that exceeded a TWA of 2000 p.p.b. Our data indicate a significant (P < 0.05) 2-fold increase in frequencies of hprt variant (mutant) lymphocytes (Vf) in workers exposed to >150 p.p.b. BD, compared with workers exposed to <150 p.p.b. There was no significant effect from individual GSTM1, GSTT1 or mEH genotypes in workers exposed to <150 p.p.b. BD. In workers exposed to >150 p.p.b., individuals with at least one polymorphic mEH His allele (His/His or His/Tyr genotypes) had a significant (P < 0.001) 3-fold increase in Vf (mean Vf x 10(-6) +/- SE = 13.25 +/- 1.78) compared with individuals with the Tyr/Tyr genotype (mean Vf x 10(-6) +/- SE = 4.02 +/- 0.72). There was no significant effect from individual GSTM1 or GSTT1 polymorphisms, but combined polymorphism analysis showed that the genetic damage was highest in individuals who had at least one mEH His allele and either the GSTM1 and/or GSTT1 null genotypes (hprt Vf = 14.19 +/- 2.30 x10(-6)). In contrast, this response was not observed in individuals exposed to levels of BD < 150 p.p.b. These results indicate that polymorphisms in the mEH gene may play a significant role in human sensitivity to the genotoxic effects of BD exposure, and that the hprt mutant lymphocyte assay can serve as a sensitive biomarker of genotoxicity for monitoring occupational exposure to BD in industrial settings. Additional investigations in larger populations of workers are needed to confirm our results and to characterize the possible role of additional mEH polymorphisms in the induction of genetic damage associated with occupational exposure to butadiene.

Alleles↗

PubMed1990

Allelic genealogy under overdominant and frequency-dependent selection and polymorphism of major histocompatibility complex loci.

To explain the long-term persistence of polymorphic alleles (trans-specific polymorphism) at the major histocompatibility complex (MHC) loci in rodents and primates, a computer simulation study was conducted about the coalescence time of different alleles sampled under various forms of selection. At the same time, average heterozygosity, the number of alleles in a sample, and the rate of codon substitution were examined to explain the mechanism of maintenance of polymorphism at the MHC loci. The results obtained are as follows. (1) The coalescence time for neutral alleles is too short to explain the trans-specific polymorphism at the MHC loci. (2) Under overdominant selection, the coalescence time can be tens of millions of years, depending on the parameter values used. The average heterozygosity and the number of alleles observed are also high enough to explain MHC polymorphism. (3) The pathogen adaptation model proposed by Snell is incapable of explaining MHC polymorphism, since the coalescence time for this model is too short and the expected heterozygosity and the expected number of alleles are too small. (4) From the mathematical point of view, the minority advantage model of frequency-dependent selection is capable of explaining a high degree of polymorphism and trans-specific polymorphism. (5) The molecular mimicry hypothesis also gives a sufficiently long coalescence time when the mutation rate is low in the host but very high in the parasite. However, the expected heterozygosity and the expected number of alleles tend to be too small. (6) Consideration of the molecular mechanism of the function of MHC molecules and other biological observations suggest that the most important factor for the maintenance of MHC polymorphism is overdominant selection. However, some experiments are necessary to distinguish between the overdominance and frequency-dependent selection hypotheses.

Alleles↗

PubMed2006

Interleukin-10 gene promoter polymorphisms and their protein production in peritoneal fluid in patients with endometriosis.

Although associations of interleukin-10 (IL-10) gene promoter polymorphisms and their protein production with endometriosis risk have been reported, the correlations remain controversial. The objective of this study was to determine IL-10 gene promoter polymorphisms at -1082, -819 and -592 sites and their protein production in peritoneal fluid (PF) in patients with and without endometriosis. IL-10 gene promoter polymorphisms at -1082 site were detected by amplification refractory mutation system (ARMS)-PCR and that at -819 and -592 sites was genotyped by restriction fragment length polymorphism (RFLP)-PCR. Protein levels of IL-10 in PF were measured by enzyme-linked immunosorbent assay (ELISA). There were no significant differences in the genotype and allele frequencies of IL-10 gene promoter polymorphisms at position -1082 between the endometriosis and the control groups. However, the frequency of -819 or -592 C alleles was significantly increased in patients with endometriosis compared with controls. The protein levels of IL-10 in PF were statistically higher in the endometriosis group than in the control group. Moreover, the polymorphisms at -1082, -819 and -592 sites were associated with protein levels of IL-10 in PF in the endometriosis group while in the control group only the polymorphisms at position -1082 correlated with protein levels. Increased frequency of -819 or -592 C allele and increased protein production of IL-10 in PF in patients with endometriosis compared with controls and correlations of polymorphisms at -819 and -592 sites with protein levels of IL-10 in PF in patients with endometriosis may suggest that polymorphisms at -819 and -592 sites and their protein production are associated with endometriosis risk.

Ascitic Fluid↗

PubMed1994

A comparison of the allelic frequencies of ten DNA polymorphisms associated with factor VIII and factor IX genes in Thai and Western European populations.

The frequency of five factor VIII gene intragenic and linked DNA polymorphisms and five factor IX gene intragenic polymorphisms was studied in Thai females. The polymorphisms in the FVIII gene were detected by restriction enzymes BclI, XbaI, BglI and at linked loci DX13 (DXS15) and St14 (DXS52) by BglII and TaqI, respectively, and in the FIX gene by MseI, DdeI, XmnI, TaqI and HhaI. With the exception of the BglI restriction fragment length polymorphism (RFLP), which is absent in Thais, factor VIII polymorphism frequencies were similar in Thais and Caucasians. Combined use of XbaI and TaqI/St14 resulted in a heterozygosity rate of greater than 90% in Thai females. For FIX, the recently described MseI RFLP in the 5' flanking region was the most informative polymorphism in Thais, 43% of females being heterozygous. The other four polymorphisms added little to the overall heterozygosity rate. The appropriate polymorphisms were used to track defective factor VIII and IX genes through 22 Thai pedigrees with haemophilia to enable carrier status to be assigned to female family members. The information obtained during this study will form the basis for carrier detection and prenatal diagnosis of haemophilia A and B by DNA polymorphism analysis in Thailand.

Alleles↗

PubMed2001

Association analyses between genetic polymorphisms of endothelial nitric oxide synthase gene and hypertension in Japanese: The Suita Study.

OBJECTIVES: Endothelium-derived nitric oxide plays a key role in the regulation of vascular tone. Recently, endothelial nitric oxide synthase (eNOS) gene polymorphisms were reported to be associated with hypertension or coronary spasm. We investigated the association between the eNOS gene polymorphisms and hypertension in a large population-based sample of 4055 Japanese. DESIGN AND METHODS: We investigated two polymorphisms of the eNOS gene, Glu298Asp polymorphism of exon 7 and T(-786)C polymorphism of the promoter region. The genotype distribution in hypertensive subjects was compared to that in the other subjects. The influence of the genotype on blood pressure values was analyzed in the subjects not taking hypertensive medication. The promoter activities of the eNOS gene with the (-786)T or (-786)C allele were measured by a luciferase reporter gene assay. RESULTS: There was significant linkage disequilibrium between the two polymorphisms (P < 0.0001). The genotype distribution of the Glu298Asp or T(-786)C polymorphism did not differ between the hypertensive and the other subjects. No significant differences in the blood pressure of subjects not taking hypertensive medication were observed among the three genotypes of Glu298Asp or T(-786)C polymorphisms. No significant differences in the promoter activity were observed between bovine endothelial cells transfected with the (-786)T and (-786)C alleles. CONCLUSIONS: Our data suggested that these polymorphisms of the eNOS gene are unlikely to be major factors in the susceptibility to hypertension in the Japanese population studied.

Adult↗

PubMed2003

Effects of ACE I/D and AT1R-A1166C polymorphisms on blood pressure in a healthy normotensive primary care population: first results of the Hippocates study.

BACKGROUND: Several studies have assessed the relationship between the angiotensin-converting enzyme (ACE) I/D or angiotensin II type 1 receptor (AT(1)R)-A C polymorphisms and blood pressure (BP). Since most data have been obtained in selected populations, the present study was performed in a healthy normotensive primary care population. OBJECTIVE: To investigate the individual effects of the aforementioned polymorphisms and their interaction on BP. METHODS: This cross-sectional study included 198 healthy subjects. Office BP was measured and polymorphisms were genotyped (polymerase chain reaction). Polymorphism interaction was tested using the following model: systolic blood pressure (SBP) (or diastolic blood pressure, DBP) = b(0)+ b(1)X + b(2)Y + b(3)XY, in which X and Y represent the polymorphisms' risk alleles. RESULTS: The ACE I/D polymorphism was associated with SBP (P = 0.002) and DBP (P = 0.004); highest pressures tracked with the DD genotype. Furthermore, in multiple linear regression analysis the ACE D allele was associated with SBP (P = 0.005) and DBP (P = 0.001), when adjusted for body mass index (BMI) and age. With respect to the AT(1)R-A C polymorphism, SBP was highest in the CC genotype (P = 0.025). In linear regression analysis the C allele was not associated with SBP. No synergistic effect of ACE D and AT(1)R C alleles on BP was found. Nevertheless, highest DBP tracked with the DDCC combination in comparison with other homozygous allele combinations (P = 0.030). CONCLUSIONS: This study confirmed an association of ACE I/D and AT(1)R-A C polymorphisms with BP in a healthy normotensive primary care population. Although synergistic effect of both polymorphisms on BP does not seem to be present, an additive effect on DBP is likely.

Adenine↗

PubMed2004

A 6 bp polymorphism in the thymidylate synthase gene causes message instability and is associated with decreased intratumoral TS mRNA levels.

OBJECTIVE: A 6 bp deletion polymorphism in the thymidylate synthase (TS) gene was investigated in order to determine its function. METHODS: A luciferase system was used to investigate the function of the 6 bp/1494 polymorphism in vitro. A group of 43 patients with colorectal carcinoma were evaluated for the 6 bp/1494 polymorphism and for intratumoral TS mRNA levels in vivo. RESULTS: The 3'UTR of TS containing the +6 bp polymorphism resulted in an approximate 35% decrease in luciferase activity and mRNA levels, while the TS-3'UTR bearing the -6 bp deletion resulted in an approximate 70% decrease in luciferase activity and mRNA levels. The TS-3'UTR construct containing the -6 bp/1494 deletion also had a higher rate of message degradation compared to the +6 bp/1494 construct. Individuals homozygous for the insertion (+6 bp/+6 bp) had significantly higher TS mRNA levels compared to individuals that were homozygous for the deletion (-6 bp/-6 bp) (P < 0.007). We determined the frequency of the -6 bp/1494 deletion polymorphism to be 41% in non-Hispanic whites, 26% in Hispanic whites, 52% in African-Americans and 76% in Singapore Chinese. CONCLUSIONS: These results suggest that the -6 bp/1494 deletion polymorphism in the 3'UTR of TS is associated with decreased mRNA stability in vitro and lower intratumoral TS expression in vivo. Further, the 6 bp/1494 polymorphism varies greatly within different ethnic populations and is in linkage disequilibrium with the TS 5' tandem repeat enhancer polymorphism. Taken together, these data suggest that the 6 bp/1494 polymorphism may be a useful screening tool in predicting TS mRNA expression.

3' Untranslated Regions↗

PubMed1995

Genetic polymorphism of cytochromes P450 1A1, 2D6 and 2E1: regulation and toxicological significance.

Because of important roles of cytochromes P450 in the metabolic activation of many precarcinogens, extensive research in the past has focused on the relationship between the distribution of polymorphic variants of different isozymes of P450 and cancer susceptibility. In this respect three isozymes in particular have been studied, CYP1A1, CYP2D6, and CYP2E1. Both CYP1A1 and CYP2E1 participate in the metabolism of many suspected as well as established carcinogens, whereas essentially only one carcinogenic substrate has been identified for CYP2D6. Polymorphic sites for the three CYP genes have been identified both in the open reading frame as well as in introns and the regulatory 5' region. In the present contribution we summarize the molecular epidemiological research relating CYP polymorphism to cancer susceptibility and in some cases to toxicity. An interesting polymorphism has been described on the phenotypic level for the inducibility of CYP1A1, a polymorphism that in some studies has been related to a mutation in the 3' flanking region of the CYP1A1 gene. However, the genetic basis for this polymorphism might be inherited in the genes coding for proteins responsible for the induction of CYP1A1, ie, the Ah receptor or the ARNT protein. Data on lung cancer and CYP1A1 gene polymorphism indicate that carriers of genotypes associated with CYP1A1 inducibility are at higher risk for cancer, but that, at least for Caucasians, the recognized mutations probably identify only a fraction of the inducible individuals. The amount of DNA adducts correlates well in some studies to the individual activity registered for CYP1A1. CYP2D6 phenotype and genotype have mainly been related to the incidence of lung cancer, but results from 13 different studies now show an absence of any significant correlation between these parameters. In the case of CYP2E1, some studies indicate a relationship between lung cancer and the occurrence of a rare allele, although future research is needed in order to establish a significant relationship. It is concluded that, at the present stage, none of the polymorphic sites determined in the CYP genes can yet be used as markers for increased lung cancer risk. Future research in this field might be focused on the establishment of new polymorphic sites in the CYP genes, affecting inducibility or function, and on the molecular basis for the interesting differences in CYP1A1 inducibility.

Animals↗

PubMedDate not supplied

Genetic polymorphisms and heart failure.

Heart failure is a complex clinical syndrome. There is evidence for a genetic contribution to the pathophysiology of heart failure. Considering the fundamental role of neurohormonal factors in the pathophysiology and progression of cardiac dysfunction and hypertrophy, variants of genes involved in this system are logical candidate genes in heart failure. In this report, genetic polymorphisms of the major neurohormonal systems in heart failure will be discussed. Studies on polymorphisms of the renin-angiotensin-aldosterone system (RAAS), adrenergic receptor polymorphisms, endothelin (receptor) polymorphisms, and a group of miscellaneous polymorphisms that may be involved in the development or phenotypic expression of heart failure will be reviewed. Research on left ventricular hypertrophy is also included. The majority of genetic association studies focused on the ACE I/D polymorphism. Initial genetic associations have often been difficult to replicate, mainly due to problems in study design and lack of power. Promising results have been obtained with genetic polymorphisms of the RAAS and sympathetic system. Considering the evidence so far, a modifying role for these polymorphisms seems more likely than a role of these variants as susceptibility genes. Besides the need for larger studies to examine the effects of single nucleotide polymorphisms and haplotypes, future studies also need to focus on the complexity of these systems and study gene-gene interactions and gene-environment interactions.

Heart Failure↗