Ferenc Somogyvári

Evaluation of the interactions of common genetic mutations in stroke subtypes

Abstract.Objective: Ischemic stroke is a frequent heterogeneous multifactorial disease that is affected by several genetic mutations and environmental factors. We hypothesised the clinical importance of the co-occurrence of common, unfavorable genetic mutations in the development of different stroke subtypes. Method and material: The Factor V Leiden G1691A (Leiden V), the prothrombin G20210A and the methylenetetrahydrofolate reductase C677T (MTHFR C677T) mutations and the angiotensin-converting enzyme I/D (ACE I/D) and apolipoprotein E (APOE) genotypes were examined by the PCR technique in 689 ischemic stroke patients and 652 stroke-free controls. Logistic regression models were used to estimate the relative risks of different stroke subtypes for different genotype combination patterns. Results: The ACE D/D genotype alone or in combination with the MTHFR 677T or the APOE 4 allele or with both was highly specific for small-vessel infarction. The Leiden V mutation alone or in different combination patterns with the ACE D, APOE 4 and MTHFR 677T alleles was specifically predisposed to large-vessel infarction. The APOE 4 allele alone was calculated to be a general, minor genetic risk factor for ischemic stroke. The MTHFR 677T allele alone was not a risk factor for any stroke subtype. In the different specific predisposition gene combinations, however, both the APOE 4 and MTHFR 677T alleles could increase the relative risk of the given stroke subgroup. Conclusions: Common mutations which alone are minor or non-significant risk factors for ischemic stroke can yield, in specific combination patterns, a highly significant, moderate genetic risk of specific stroke subtypes.

Association of beta-defensin 1 single nucleotide polymorphisms with Crohn's disease

Objective. It has been suggested that deficient defensin expression is associated with the chronic inflammation of Crohns disease. The regional localization of Crohns disease, ileal or colonic disease can be linked to different defensin profiles. As constitutive β-defensin 1 has a colonic expression, we considered it of interest to investigate single nucleotide polymorphisms (SNPs) of the β-defensin 1 gene (DEFB1) in Crohns disease. Material and methods. Three SNPs of the DEFB1 gene, DEFB1 G-20A (rs11362), DEFB1 C-44G (rs1800972) and DEFB1 G-52A (rs1799946), were genotyped either by Custom TaqMan® SNP genotyping assays or by restriction fragment length polymorphisms (RFLP) in 190 patients with Crohns disease and 95 Hungarian controls. Results. It was found that the G-20A and C-44G SNPs had a strong association with the colonic and ileocolonic localizations of the disease, respectively, but no association was detected for the ileal localization. A significantly higher frequency of the GA genotype of G-20A was observed among patients with colonic localization (60%) as compared with healthy controls (39%), with an odds ratio (OR) of 2.39. The GG genotype of C-44G SNP, which is regarded as a protective genotype, was much less frequent (4%) among patients than among controls (12%), OR 3.367. Conclusions. These results indicate that genetic variations in the DEFB1 gene encoding constitutive human β-defensin 1 may be associated with the risk for Crohns disease and may determine disease phenotype, e.g. colonic localization.

Evaluation of the modifying effects of unfavourable genotypes on classical clinical risk factors for ischaemic stroke

Objectives: Ischaemic stroke is a frequent heterogeneous multifactorial disease that is affected by a number of genetic mutations and environmental factors. We hypothesised the clinical importance of the interactions between common, unfavourable genetic mutations and clinical risk factors in the development of ischaemic stroke. Methods: The Factor V Leiden G1691A (Leiden V), the prothrombin G20210A, the methylenetetrahydrofolate reductase C677T (MTHFR C677T) mutations, the angiotensin converting enzyme I/D (ACE I/D), and apolipoprotein allele e4 (APO e4) genotypes were examined by the polymerase chain reaction (PCR) technique in 867 ischaemic stroke patients and 743 healthy controls. Logistic regression models were used to estimate the roles of the co-occurrences of the clinical risk factors and common genetic mutations in ischaemic stroke. Results: The Leiden V mutation in combination with hypertension or diabetes mellitus increased the risk of ischaemic stroke. We found synergistic effects between the ACE D/D and MTHFR 677TT genotypes and drinking or smoking. The presence of the APO e4 greatly facilitated the unfavourable effects of hypertension, diabetes mellitus, smoking, or drinking on the incidence of ischaemic stroke. Conclusion: In certain combinations, pairing of common unfavourable genetic factors, which alone confer only minor or non-significant risk, with clinical risk factors can greatly increase the susceptibility to ischaemic stroke.

Apolipoprotein A5 gene promoter region T-1131C polymorphism associates with elevated circulating triglyceride levels and confers susceptibility for development of ischemic stroke

The possible pathogenic role of triglycerides (TG) in the development of ischemic stroke is still under extensive investigation. Recently, apolipoprotein (apo)A5 gene promoter region T-1131C polymorphism has been shown to associate with elevated serum TG levels. In the current work, a total of 302 subjects were classified as being large vessel-associated, small vessel-associated, or belonging to a mixed group of ischemic stroke-affected patients. The level of TG was increased in all groups (p<0.01). The apoA5-1131C allele frequency was approximately twofold in all groups of stroke patients compared with the controls (5 vs 10–12%; p<0.05); and the apoA5-1131C allele itself was also found to associate with increased TG levels in all groups. In a multivariate logistic regression analysis model adjusted for differences in age, gender, serum cholesterol, hypertension, pressence of diabetes mellitus, smoking and drinking habits, and ischemic heart disease, a significantly increased risk of developing stroke disease was found in patients carrying the apoA5-1131C allele (p<0.05; odds ratio OR=2.1 [1.3–4.7]); this association was also proven for all subtypes of the stroke. The results presented here suggest that the apoA5-1131C allele is an independent risk factor for the development of stroke. Being that apoA5 gene is under the control of the peroxisome proliferator-activated receptor α, theoretically, the current observations also can have long-term therapeutic consequences.

Evaluation of the roles of the Leiden V mutation and ACE I/D polymorphism in subtypes of ischaemic stroke

Objective The Leiden V mutation, which causes activated protein C resistance and thrombophilia, has been found to be a risk factor for venous thrombosis. The angiotensin converting enzyme (ACE) D allele indirectly exerts an unfavourable effect on the vasoregulatory system. In this study, the frequency of these mutations was analysed in different subtypes of ischaemic stroke. Method and material According to the clinical and radiological features 664 Hungarian patients who had suffered acute ischaemic stroke were divided into 3 subtypes: small and large vessel infarcts and a mixed type. In all 664 patients, the Leiden V mutation and ACE I/D polymorphism were examined by means of the PCR technique. The frequencies of the different genotypes for the Leiden V mutation and ACE I/D polymorphism in the 3 subgroups of stroke were compared with 199 stroke-free control subjects whose MRI findings were normal. Results No significant associations were found between the overall group of cerebral infarctions and the Leiden V, ACE I/D and ACE D/D genotypes. The ACE D/D genotype was significantly more common in the patients with small deep infarcts (40.3 %; p < 0.0005; OR 2.31, 95 % CI 1.49–3.57) than in the control group (22.6 %). The Leiden V mutation was significantly more common in patients with large infarcts (13.6 %; p < 0.025; OR 2.25, CI 1.16–4.34) than in the stroke-free control subjects (6.5 %). Conclusions The ACE D/D genotype possibly contributes to the occurrence of small-vessel infarcts rather than large vessel infarcts. The Leiden V mutation might predispose to large brain infarcts. Neither the Leiden V factor nor the ACE D/D genotype has been proved to be a risk factor for ischaemic stroke as a whole.

Specific APO E genotypes in combination with the ACE D/D or MTHFR 677TT mutation yield an independent genetic risk of leukoaraiosis

Objective – Ischaemic demyelination of the white matter of the brain is a frequent clinical entity. In the neuroimaging terms, it is referred to as leukoaraiosis. We earlier found that the co‐occurrence of the homozygous methylenetetrahydrofolate reductase (MTHFR) 677TT and angiotensin‐converting enzyme D/D (ACE D/D) genotypes yielded a highly significant moderate risk of leukoaraiosis. On the assumption of further genetic interactions, we have now investigated whether the different apolipoprotein E (APO E) genotypes, in pairwise combinations with the MTHFR 677TT or ACE D/D mutation, could lead to an increased risk of leukoaraiosis.

Evaluation of the roles of common genetic mutations in leukoaraiosis.

Objectives– Leukoaraiosis, a relatively frequent neuroimaging entity, is presumed to be primarily a vascular problem. However, it can be explained only in part by vascular risk factors. With the assumption of genetic susceptibility, the roles of common genetic polymorphisms and mutations in leukoaraiosis were examined in this study. Material and methods– A detailed clinical scrutiny of 843 Hungarian neurological patients with mild cognitive‐like complaints revealed 229 subjects with leukoaraiosis that was probably vascular in origin: 143 with leukoaraiosis alone (group 1), and 86 with leukoaraiosis plus cerebral infarction (group 2). In all 229 patients, the methylenetetrahydrofolate reductase C677T (MTHFR C677T) mutation and angiotensin‐converting enzyme (ACE I/D) polymorphism were examined by means of the PCR technique. The prevalences of the different genotypes for the examined mutations in the 2 groups were analysed in comparison with the data on 362 neuroimaging alteration‐free subjects as controls. Results– The ACE D/D genotype (38.37%, P<0.0005; OR 2.46, 95% CI, 1.49–4.08) and ACE D allele (61%; P<0.001) were more frequent in group 2 than in the control group (20.17%; 47%). Neither the homozygous nor the heterozygous MTHFR C677T mutation alone was found to be a risk factor for leukoaraiosis. The homozygous MTHFR C677T mutation combined with the ACE D/D genotype was significantly more frequent in group 1 (11.89%, P<0.0005; OR 4.75, 95% CI, 2.12–10.65), in group 2 (12.79%, P<0.0005; OR 5.16, 95% CI, 2.12–12.6) and in combined group 1+2 (12.23%, P<0.0005; OR 4.9, 95% CI, 2.33–10.3) than in the control group (2.76%). Conclusion– These data indicate that the contributions of the ACE D/D genotype and the homozygous MTHFR C677T mutation to leukoaraiosis should be taken into consideration not as major, but as additive factors. These findings draw attention to the fact that genetic polymorphisms that alone are insignificant can be risk factors for leukoaraiosis if they cluster in the same subjects.

Association of vitamin D receptor gene polymorphisms and Parkinson's disease in Hungarians

Vitamin D receptor (VDR) gene encodes a transcription factor that influences calcium homeostasis and immunoregulation, and may play a role in neurological disorders including Parkinsons disease (PD). The investigations of the association between VDR and PD in different populations revealed various results. In a present study 100 PD patients and 109 healthy controls from the Hungarian population were genotyped for four polymorphic sites (BsmI, ApaI, FokI and TaqI) in the VDR gene. The polymorphisms were determined by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). Our results demonstrate an association between the FokI C allele and PD; the frequency of the C allele was significantly higher in PD patients than in controls, suggesting that this polymorphism may have a role in the development of PD in these patients.

Coexistence of angiotensin II type-1 receptor A1166C and angiotensin-converting enzyme D/D polymorphism suggests susceptibility for small-vessel-associated ischemic stroke.

The renin-angiotensin system plays an important role in the maintenance of blood pressure homeostasis. The angiotensin-converting enzyme (ACE) converts angiotensin I into angiotensin II. Angiotensin II, which binds the angiotensin II type-1 receptor (AT1R), is a potent vasoconstrictor. On a pathophysiological basis, both ACE I/D and AT1R A1166C polymorphism lead to an enhanced activity of the angiotensin II-AT1R axis, thereby possibly contributing to circulatory disturbances. A mutually facilitatory effect may be presumed between the two polymorphisms. We examined whether this synergistic effect is involved in the evolution of different types of ischemic stroke. Genetic and clinical data on 308 consecutive patients with acutely developing ischemic stroke were analyzed. A total of 272 stroke and neuroimaging alteration-free subjects served as a control group. Univariate and logistic regression statistical approaches were used. The ACE D allele combined with the AT1R 1166C allele did not yield a risk of ischemic stroke. However, the co-occurrence of the homozygous ACE D/D and at least one AT1R 1166C allele was more frequent in the ischemic stroke group than in the control group (22.4 vs 11%, p<0.005, OR, 2.33; 95% CI, 1.46–3.7). After specific subgroup analysis, this synergistic association was even stronger for small-vessel ischemic stroke (OR, 3.44; 95% CI, 1.9–6.24; p<0.0005). Multivariate logistic regression analysis of the data confirmed this association (adjusted OR, 3.54, 95% CI, 1.88–7.16; p<0.0005). Our results demonstrate that ACE D/D and AT1R 1166C polymorphism were associated with the development of small-vessel ischemic stroke through a mutually facilitatory interplay between them. Genetic interactions might contribute to the altered functional network in renin-angiotensin system in vascular disorders.

Increased prevalence of platelet glycoprotein IIb/IIIa PLA2 allele in ischaemic stroke associated with large vessel pathology

INTRODUCTION Platelet glycoprotein IIb/IIIa is a membrane receptor with a central function in the platelet adhesion and ultimately in the thrombus formation. Two major variants of the gene encoding the IIIa subunit, called PLA1 (A1) and PLA2 (A2), have been identified in the general population. There are indications that the A2 allele can also be associated with acute thrombosis or stroke. The purpose of this study was to study the distribution of the A2 allele in different vascular subtypes of stroke disease. MATERIALS AND METHODS A total of 638 consecutive patients were analyzed and classified as having large vessel pathology (n=168) or a small vessel infarct (n=210). Localization of the vascular occlusions was deducted from analysis of the magnetic resonance imaging (MRI) scan results in stroke patients. The remainder patients were listed into a mixed vascular pathology group (n=167). Patients with other or poorly characterized stroke etiology were excluded from the study (n=93). RESULTS In the small vessel and mixed vascular pathology groups, the PLA2 allele frequency was similar to that in the controls. By contrast, PLA2 allele frequency was approximately two-fold higher in patients with large vessel pathology (23.3%) than in the stroke-free control subjects (11.7%, p<0.0005). Multivariate logistic regression analysis of data confirmed this association with an odds ratio (OR) of 2.9 (95% confidence interval [CI]: 1.6-4.9, p<0.0005). CONCLUSIONS These data suggest that the PLA2 allele is more frequent in brain infarcts associated with large-vessel occlusion.