Aldosterone synthase gene (CYP11B2) promoter polymorphism as a risk factor for ischaemic stroke in Tunisian Arabs.

INTRODUCTION: We investigated the contribution of aldosterone synthase CYP11B2 polymorphism (C-344T) to the age-related changes in blood pressure in stroke patients. SUBJECTS AND METHODS: Study subjects comprised 329 stroke patients (121 normotensive, 208 hypertensive) and 444 healthy controls. Genotyping was done by PCR-RFLP, and the contribution of CYP11B2 polymorphism to the risk of stroke was analysed by regression analysis. RESULTS: The T allele, and CT, TT, and CT + TT genotypes, independently of sex and age, were significantly associated with increased stroke risk. Varied distributions of CYP11B2 genotypes were noted among patients with respect to gender, age and hypertension status, being pronounced in hypertensive patients. Both systolic and diastolic blood pressure were positively correlated with the presence of T allele. Mean systolic and diastolic blood pressure were significantly higher among young (< 60 years) CT and TT genotype carriers. Regression analysis confirmed the positive association of CT and TT genotypes and systolic blood pressure, and the negative association of diastolic blood pressure with odds of stroke development. Taking normotensive patients as reference, regression analysis identified TT genotype, age and female gender to be independently associated with increased odds of stroke. CONCLUSION: Compared to CC genotype, CT and TT CYP11B2 genotypes are independently associated with increased stroke index.

Association of PAI-1 4G/5G and -844G/A gene polymorphisms and changes in PAI-1/tissue plasminogen activator levels in myocardial infarction: a case-control study.

BACKGROUND: Myocardial infarction (MI) is induced by acquired and inherited risk factors, including the plasminogen activator inhibitor-1 (PAI-1) -844G/A and -675G/A (4G/5G) gene variants. OBJECTIVE: The aim of this study was to investigate the association between PAI-1-844G/A and 4G/5G polymorphisms and changes in PAI-1 and tissue plasminogen activator (tPA) levels in MI in a Tunisian population. METHODS: This was a case-control study involving 305 patients with MI and 328 unrelated healthy controls. PAI-1 genotyping was done by polymerase chain reaction-restriction fragment length polymorphism (RFLP) (-844G/A) or by polymerase chain reaction-allele specific amplification. PAI-1 and tPA levels were assayed by serological assays. RESULTS: In contrast to tPA levels, mean plasma PAI-1 antigen levels were higher in cases than in control subjects. The elevation in PAI-1 levels was more pronounced in -844A and 4G allele carriers. Significantly higher frequencies of (mutant) 4G and -844A alleles and 4G/4G and -844A/-844A genotypes, and corresponding lower frequencies of (wild-type) 5G and -844G alleles and 5G/5G and -844G/-844G genotypes were seen in patients than in controls. Increased prevalence of 4G/-844A and decreased prevalence of 5G/-844G haplotypes were seen in patients than in controls, thereby conferring a susceptibility and protective nature to these haplotypes, respectively. Regression analysis confirmed the independent association of 4G/4G and -844A/A with MI, after controlling for a number of covariates. CONCLUSION: This study indicated that the risk of MI was notably high in 4G and -844A carriers with elevated plasma PAI-1 and were associated with reduced tPA levels.

Interaction of angiotensin-converting enzyme and apolipoprotein E gene polymorphisms in ischemic stroke involving large-vessel disease.

A relationship between apolipoprotein E (Apo E) genotype and angiotensin-converting enzyme (ACE) insertion-deletion (Ins-Del) mutation and stroke was suggested. We investigated the association of Apo E4 and ACE Ins/Del genotypes with stroke risk and changes in serum lipids in 228 consecutive Tunisian stroke patients, and 323 age-and gender-matched controls. Comparable frequencies of ACE Ins/Del alleles were seen between patients and controls. The prevalence of Apo epsilon3 allele and Apo E3/E3 were lower (P < 0.001), while the frequency of Apo epsilon4 allele and epsilon4-containing genotypes (E3/E4 and E4/E4) were elevated (P < 0.001) among patients. Higher proportion of Apo E4-carrying + ACE Del/Del positive cases were seen in young (<50 years) patients (P = 0.012), and was associated with large vessel stroke (P = 0.035). Mean serum cholesterol, LDL, HDL, and triglycerides were comparable between E4-containing and no E4-containing and ACE Del/Del-positive patients. Apo E4 and ACE Del/Del genotype combination substantially increase stroke risk, supporting the notion that interactions of multiple gene variants influence stroke pathogenesis.

Polymorphisms of the human platelet alloantigens HPA-1, HPA-2, HPA-3, and HPA-4 in ischemic stroke.

Polymorphism in human platelet antigen (HPA)-1 and HPA-3 (GPIIb/IIIa), HPA-2 (GPIb/IX), HPA-4 (GPIIIa), and HPA-5 (GPIa/IIa) was investigated in 329 stroke patients and 444 matched control subjects. HPA genotyping was done by PCR-SSP method. Lower HPA-1a (P < 0.001) and higher HPA-1b (P < 0.001) allele frequencies were seen in patients than control subjects, and homozygosity for HPA-1b (P < 0.001) alleles was more prevalent in stroke cases than in controls. The allele and genotype distributions of the other HPA polymorphic variants were similar between cases and controls. Select HPA combined genotypes comprising the 2121 (Pc = 0.008) and 2221 (Pc = 0.018) genotypes, which were positively associated, and the 1111 (Pc < 0.001), which was negatively associated with stroke, thereby conferred a disease susceptibility and protective nature to these genotype combinations. Multivariate analysis confirmed the negative association of the 1111 (P < 0.001) and the positive association of the 2121 (P = 0.017) combined genotypes with stroke, after adjustment for a number of covariates. This is the first evidence demonstrating differential association of the common 4 HPA gene variants and specific HPA genotype combinations with stroke.

Association of human platelet alloantigen 1 through 5 polymorphisms with ischemic stroke.

Polymorphisms in human platelet alloantigen (HPA)-1 and HPA-3 (GPIIb/IIIa), HPA-2 (GPIb/IX), HPA-4 (GPIIIa) and HPA-5 (GPIa/IIa) were investigated in 216 stroke patients and 318 matched control subjects. HPA genotyping was done by the polymerase chain reaction method using sequence-specific primers. Higher frequencies of the HPA-1 a/b (p < 0.001) and HPA-5 a/b (p < 0.001) allele, together with HPA-1 b/b, HPA-5 a/b and HPA-5 b/b genotypes were seen in patients, which was confirmed by regression analysis after controlling for a number of confounding variables. Furthermore, HPA-1 b/b and HPA-5 b/b were significantly associated with the extent of neurological symptoms, and with the recurrence of stroke. Both susceptible (1a/ b -2a/a-3a/ b -4a/a-5a/ b ) and protective (1a/a-2a/a-3a/a-4a/a-5a/a; 1a/a-2a/a-3a/ b -4a/a-5a/a; 1a/ b -2a/a-3a/a-4a/a-5a/a; 1a/ b -2a/a-3a/ b -4a/a-5a/a) HPA genotypes were identified. This is the first evidence demonstrating differential association of the common 5 HPA gene variants with stroke, with HPA-1b and HPA-5b representing strong genetic risk factors.

Association of PAI-1 4G/5G and -844G/A gene polymorphism and changes in PAI-1/tPA levels in stroke: a case-control study.

Mutations in the plasminogen activator inhibitor-1 (PAI-1) gene, along with altered PAI-1 and tissue-type plasminogen activator (tPA) levels, have been implicated in stroke pathogenesis. We investigated the association of PAI-1 and tPA levels with stroke as a function of PAI-1 4G/5G and -844G/A genotypes, as well as the link between these PAI-1 gene variants and stroke risk, in a case-control study of 135 ischemic stroke patient, diagnosed according to clinical and radiologic findings and confirmed by computed tomography scan. Controls (n = 118) were age- and sex-matched and had no personal/family history of stroke. PAI-1 4G/5G and -844G/A genotyping were done by polymerase chain reaction-restriction fragment length polymorphism, and PAI-1 and tPA levels were measured by enzyme immunoassay. Significant elevation in PAI-1 and marked reduction in tPA levels were seen in stroke patients and were correlated with 4G/5G, but not with -844G/A, PAI-1 variants. Whereas the frequencies of 4G or -844A alleles were comparable between patients and controls, 4G/4G carriers had reduced risk of stroke compared with other genotypes (odds ratio [OR] = 0.54; 95% confidence interval [CI] = 0.31-0.95). The 4G/-844A haplotype also was more closely associated with reduced stroke risk (OR = 0.43; 95% CI = 0.20-0.97) than 5G/-844A or 4G/-844G haplotypes. Regression analysis demonstrated that 4G homozygosity (OR = 0.176), hypertension (OR = 6.288), and body mass index (OR = 1.325) were independent predictors of stroke. The protective effect of 4G allele against stroke suggests involvement of PAI-1 4G/5G polymorphism in stroke through a mechanism not related to fibrinolysis, possibly involving altered plaque stabilization, and/or through antagonism of tPA effects.

Association of apolipoprotein E gene polymorphism with ischemic stroke involving large-vessel disease and its relation to serum lipid levels.

A relationship between apolipoprotein E (Apo E) genotype and stroke was previously suggested, but with inconsistent results. We investigated the relationships among serum lipid levels, Apo E alleles and genotypes, and stroke risk factors in 216 stroke patients and 282 age- and sex-matched controls. Fasting blood samples were collected for total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride level determination and for genomic DNA extraction. Apo was genotyped by polymerase chain reaction-restriction fragment length polymorphism (Cfo I) analysis. Increasing levels of total cholesterol, LDL-C, HDL-C, and triglycerides were associated with elevated stroke risk and was more pronounced in Apo E4-carrying subjects than in E3- and/or E2-carrying subjects. Apo 3 was significantly lower (0.546 vs 0.736; P < .001), whereas Apo 4 was higher in the stroke patients (0.370 vs 0.181; P < .001); Apo 2 was present at low but comparable frequencies. The prevalence of E3/E3 was lower and that of E4-containing phenotypes (E3/E4 and homozygous E4/E4) was higher in the stroke patients. The prevalence of the E4-containing phenotypes were significantly higher in ischemic versus hemorrhagic (P < .001) and in small-vessel versus large-vessel stroke cases (P < .001), and was associated with increased need for statin drugs (P = .040). Logistic regression models, after adjusting for potentially confounding variables including lipid profile, age, and sex, showed an significant association of apo 4 genotype with risk of stroke (P = .033). Our findings indicate that Apo 4 is an independent risk factor associated with an altered lipid profile in this study population.

Gene frequencies of human platelet alloantigens in Bahraini Arabs.

Human platelet antigens (HPA) are implicated in the pathophysiology of certain hematological disorders, and as varied distribution of HPA-1 alleles and genotypes were reported fordifferent countries and ethnic populations, we determined the distribution of HPA-1, -2, -3, -4, and -5 alleles, genotypes and haplotypes for 194 healthy Bahraini subjects by polymerase chain reaction with sequence specific primers. The distribution of the HPA polymorphisms was in Hardy-Weinberg equilibrium. Allele frequencies of 0.76 and 0.24 (HPA-1a and -1b), 0.77 and 0.23 (HPA-2a and -2b), 0.57 and 0.43 (HPA-3a and -3b), 0.93 and 0.07 (HPA-4a and -4b), and 0.86 and 0.13 (HPA-5a and -5b) were seen. With the exception of HPA-3a/a (30.4%), the frequencies of homozygous HPA-1a/a (56.8%), 2a/a (60.1%), 4a/a (87.2%), and 5a/a (75.7%) were higher than those of heterozygous (a/b) or homozygous (b/b) variants. Our results provide basic information for further studies of the HPA system polymorphism, which in turn will be instrumental in understanding and treating immune-mediated platelet disorders.

Association of factor V gene polymorphisms (Leiden; Cambridge; Hong Kong and HR2 haplotype) with recurrent idiopathic pregnancy loss in Tunisia. A case-control study.

Inherited thrombophilia has been shown to be linked with fetal loss. We performed a case-control study on the association between thrombosis-related polymorphisms in the factor V (FV) gene (Leiden, Cambridge, Hong Kong; HR2 haplotype) and idiopathic recurrent pregnancy loss (RPL) in Tunisian women. A total of 348 women with RPL, and 203 control women were studied, corresponding to 1,250 pregnancy losses and 1,200 successful pregnancies. FV Leiden was seen in 19.4% of patients (4.3% in the homozygous state) and in 5.5% of controls. The prevalence of the FV HR2 haplotype was similar in patients and controls, but with 7 homozygous patients for 1 control. FV Cambridge and Hong Kong were absent from both patients and controls. The study of all pregnancy losses evidenced that the frequency of the factor V Leiden polymorphism was zero in women who had mis-carried before 7 weeks of gestation, and then sharply increased to a plateau. After categorization of pregnancy losses (before 8 weeks of gestation; weeks 8 and 9; weeks 10 to 12; from the 13th week of gestation onwards), heterozygous and homozygous factor V Leiden polymorphisms, and homozygous FV HR2 haplotype, were associated with significant and independent risks of pregnancy loss during weeks 8 and 9, which increased during weeks 10 to 12, then culminated after week 12. In Tunisian women with idiopathic RPL, factor V Leiden polymorphism and homozygous FV HR2 haplotype are not a risk factor for very early pregnancy loss, before 8 weeks of gestation, but are thereafter associated with significant clinical risks, which gradually increase from the 8th week onwards.