Turgay Isbir

Angiotensin converting enzyme I/D, angiotensinogen T174M-M235T and angiotensin II type 1 receptor A1166C gene polymorphisms in Turkish hypertensive patients

Essential hypertension is a multifactorial disease in which genetic and enviromental factors play an important role. These factors differ in each population. As there are no existing data for the Turkish population, we investigated four Renin Angiotensin System (RAS) gene polymorphisms, the angiotensin converting enzyme (ACE), angiotensinogen (AGN) M235T/T174M and angiotensin II type 1 receptor A1166C polymorphism in 109 hypertensive and 86 normotensive Turkish subjects. Polymerase Chain Reaction (PCR) and Restriction Fragment Length Polymorphism (RFLP), and agarose gel electrophoresis tecniques were used to determine these polymorphism. The frequencies of person that carry ACE D allel (DD+ID) was significantly higher in hypertensive group (99.1%) than controls (80%) (P<0.000). M235T TT genotype was also found significantly higher in hypertensives than control group (20% vs 2.7%; P<0.001). The frequency of AGN 174M allele was higher in the hypertensive group than control subjects (8.76% vs 4.81%). Frequency of ATR1 C allele (AC+CC genotypes) was found higher hypertensives than controls (39.4% vs 25.9%; P = 0.054). Our results suggest that an interaction exists between the RAS genes and hypertension in Turkish population.

ANGIOTENSIN-I CONVERTING ENZYME GENE POLYMORPHISM IN TURKISH TYPE 2 DIABETIC PATIENTS

Non-insulin dependent diabetes mellitus is often associated with some complications such as nephropathy, retinopathy and neuropathy. Genes of the renin angiotensin system are potential candidate genes for diabetic complications. We investigated the relationship between angiotensin converting enzyme (ACE) gene polymorphism in type 2 diabetic patients with and without diabetic nephropathy. Seventy five patients (25 type 2 diabetic patients with nephropathy, 50 type 2 diabetic patients without nephropathy) and 37 healthy controls were studied. Gene polymorphism of ACE was determined by PCR (polymerase chain reaction) amplification using allele-spesific primers. The frequencies of ACE DD, ID and II genoypes among the patients with type 2 diabetic patients were found 48%, 42%, 10% whereas in control subjects, 27%, 60%, 13% respectively. Type 2 diabetic patients carrying DD genotype without nephropathy increased 1.77 fold than control subjects (P < 0.05). There is no significant correlation between diabetic nephropathy and ACE gene polymorphism. But we found that ACE DD genotype increased significantly in type 2 diabetic patients compared to control subjects (P < 0.05).

Association between manganese superoxide dismutase polymorphism and risk of lung cancer

Manganese superoxide dismutase (MnSOD) is one of the major enzymes responsible for the defense against oxidative damage due to reactive oxygen species (ROS) in the mitochondria. C-->T substitution in the MnSOD gene (SOD2) produces an Ala-->Val change at amino acid 16, in the mitochondrial targeting sequence of the MnSOD precursor. This seems to reduce transport of the enzyme into mitochondria, decreasing its defense capacity against oxidative stress. The present case-control study was conducted to investigate the association of SOD2 genetic polymorphism with individual susceptibility to lung cancer. Ala16Val polymorphisms were determined using polymerase chain reaction, restriction fragment length polymorphism mapping, and agarose gel electrophoresis techniques in 100 lung cancer patients and 50 healthy control subjects. The frequency of the Val allele (OR=1.297, 95% CI=1.095-1.536) and the Val/Val genotype (OR=7.00, 95% CI=2.282-21.476) was significantly higher in lung cancer patients than in control subjects. There was a combined effect of Val/Val genotype as a genetic factor with smoking as an environment factor (OR=2.24). The increase in risk of lung cancer was lesser with this combined effect than with the Val/Val genotype alone. Thus, the Val/Val genotype of SOD2 may be associated with lung cancer in a Turkish population.

Cholesterol ester transfer protein, apolipoprotein E and lipoprotein lipase genotypes in patients with coronary artery disease in the Turkish population

The aim of this study was to compare patients with coronary artery disease (CAD) to healthy objects, in order to explore a possible association between CAD and the variants in the gene encoding cholesterol ester transfer protein (CETP), apolipoprotein E (Apo E) and lipoprotein lipase (LPL). The relationship between CETP MspI, apo E and LPL PvuII gene polymorphisms and serum lipids were investigated in 173 patients with CAD and 111 healthy controls. The frequency of Apo ε4 (p < 0.05) and CETP M1 (p < 0.01) alleles were higher in the CAD group than in the control group. In the CAD group, those with the Msp M1 allele had higher levels of total cholesterol (TC) (p = 0026) and low‐density lipoprotein cholesterol (LDL‐C) than those with the Msp M2 allele. Subjects with an ε2 allele had the lowest levels of TC and LDL‐C, while subjects with the ε4 allele had the highest. In the control group, CETP, the Msp M2 allele was associated with a higher level of high‐density lipoprotein cholesterol (HDL‐C) (p = 0.012) than the Msp M1 allele. The distributions of LPL genotype and allele did not differ between the CAD and control groups. The present study demonstrates that the CETP Msp1 and Apo E gene polymorphisms are associated with variations in lipids in patients with CAD and healthy controls in Turkish population.

CCR2-64I is a risk factor for development of bladder cancer.

Chemokines are potent proinflammatory cytokines that are implicated in numerous inflammatory diseases. Proinflammatory gene polymorphisms lead to variations in the production and concentration of inflammatory proteins. We investigated a possible association between polymorphisms in chemokine and chemokine receptor genes (MCP-1 A-2518G and CCR2-V64I) and bladder cancer risk. Genotypes were determined by PCR-RFLP assays in 72 bladder cancer patients and 76 unrelated age-matched healthy controls. There were significant differences in the frequencies of the MCP-1 A-2518G (P = 0.012) and CCR2-V64I genotypes (P = 0.004) between the controls and patients. The MCP-1 A-2518G GG genotype frequencies for controls and cases were 0.039 and 0.11, respectively; individuals who had the GG genotype had a 3-fold increased risk of bladder cancer (P = 0.08). The CCR2-64I/64I genotype frequencies for controls and cases were 0.02 and 0.13, respectively; subjects carrying the 64I/64I genotype had a 5.9-fold increased risk of bladder cancer compared to the other genotypes. Individuals carrying the CCR2-V64I heterozygote or homozygous variant genotype (64I/64I + wt/64I) had a 2.9-fold increased risk of bladder cancer compared with the wild-type genotype (wt/wt). CCR2-V64I heterozygote or homozygous wild-type genotype (wt/wt + wt/64I) frequencies were significantly decreased in the patient group compared with controls. We conclude that CCR2-64I is a new risk factor for bladder cancer.

Apolopoprotein-E gene polymorphism and lipid profiles in Alzheimer's disease

In this study, the relationship between lipid profiles of sera and apolipoprotein E (apo E) gene polymorphism was investigated in 35 patients with Alzheimers disease (AD) and 29 healthy people. Apo E genotypes and allele frequencies of the AD patient group were: apo E2/3, 2 (5.7 percent); apo E2/4, 1 (2.9 percent); apo E3/3, 26 (74.3 percent); apo E3/4, 5 (14.3 percent); apo E4/4, 1 (2.9 percent); 2, 3(4.2 percent); 3, 59 (84.2 percent); 4, 8 (11.4 percent). The healthy groups apo E genotypes and allele frequencies were: apo E2/3, 1 (3.4 percent); apo E3/3, 27 (93.1 percent); apo E3/4, 1 (3.4 percent); 2, 1 (1.7 percent); 3, 56 (96.5 percent); 4, 1 (1.7 percent). In Alzheimers cases, 4 allele frequencies increased significantly as compared to the healthy group (p < 0.05). When the effects of the apo E isoforms on lipid profiles were evaluated, a relationship between apo E 4 allele and high total levels of serum cholesterol was found, whereas of apo E 2 allele was associated with the low total cholesterol of serum, although the difference was not statistically significant (p > 0.05). This study confirms the association of apo E 4 allele with lipid profiles in AD patients.

Association Between Angiotensin-Converting Enzyme Gene Polymorphism and Coronary Artery Disease

An insertion/deletion (I/D) polymorphism in the gene for angiotensin‐converting enzyme (ACE) is associated with myocardial infarction and other cardiac pathology. There is evidence for a role of the renin‐angiotensin system in cell growth and in the repair of damaged arterial walls, so the ACE gene is postulated to be a candidate gene affecting the important clinical problem of coronary artery disease (CAD). In view of the clinical importance of the ACE as a major marker of cardiovascular diseases, we investigated the I/D polymorphism of the ACE gene in Turkish CAD patients in comparison with control subjects to evaluate a possible association between CAD and the gene encoding ACE. Polymerase chain reaction, restriction fragment length polymorphism, and agarose gel electrophoresis techniques were used to determine the ACE genotype in 58 subjects. The frequencies of ACE D and ACE I allele among the patients with CAD were 62.26% and 37.73% and in the control subjects were 49.3% and 50.76%, respectively. The greater frequency of deletion allele (D) was in the CAD group than in the control subjects was significant (P < 0.01).

Association of pre-eclampsia with hyperhomocysteinaemia and methylenetetrahydrofolate reductase gene C677T polymorphism in a Turkish population.

Background:  Hyperhomocysteinaemia is a common finding in a wide variety of pathological conditions that exhibit endothelial disturbances. In the pathogenesis of pre‐eclampsia, endothelial cell activation or dysfunction has been proposed as a central feature, and the presence of hyperhomocysteinaemia in varying degrees has been detected. One of the known causes of hyperhomocysteinaemia is polymorphism in the methylenetetrahydrofolate reductase gene that lowers the activity of the enzyme.

Increased plasma levels of interleukin-6 and interleukin-8 in β -thalassaemia major

Several immunological defects can be found in patients with beta-thalassaemia, among which the impairment of neurophil and macrophage phagocytic and killing functions and the production of some cytokines are the most important. It is known that interleukin-6 (IL-6) and interleukin-8 (IL-8) are important components of the pro-inflammatory response. The plasma levels of these cytokines may be relevant in the pathophysiology of beta-thalassaemia. To assess this hypothesis, the plasma IL-6 and IL-8 concentrations in patients with beta-thalassaemia, were investigated. Fourteen patients with thalassaemia major were studied by evaluating body iron status, iron supply for erythropoiesis, and plasma IL-6 and IL-8 levels, together with 12 age-matched healthy controls. The plasma levels of IL-6 and IL-8 were determined by enzyme-linked immunosorbent assay (ELISA). Patients with beta-thalassaemia were found to have higher IL-8 concentrations than normal controls (p < 0.001) and plasma IL-6 concentrations increased significantly in the beta-thalassaemic patients compared with control subjects (p = 0.01). Serum ferritin levels of beta-thalassaemic patients were significantly higher than those of control groups (p < 0.05). IL-8 levels correlated with ferritin levels (r = 0.694; p < 0.05) and the total number of transfusions (r = 0.64; p < 0.05). Plasma IL-6 levels in beta-thalassaemic patients did not correlate with any clinical, haematological or biochemical parameters. It was also found that plasma IL-8 levels in the patients who had blood transfusions over 100 times were significantly higher than those of under 100 times (p < 0.05), whereas there was no statistical difference for IL-6. Markedly increased plasma IL-6 and IL-8 levels were documented in patients with beta-thalassaemia. Increased production of IL-6 and IL-8 might have contributed to abnormalities in iron metabolism and it is probably due to overstimulation of macrophages. Before a clinical value can be ascribed to these changes in plasma cytokine levels in beta-thalassaemia, the follow-up samples of larger series of patients with 8-thalassaemia should be evaluated.

Interaction between apolipoprotein-E and angiotensin-converting enzyme genotype in Alzheimer's disease

Both apolipoprotein-E (apo-E) 4 allele and angiotensinconverting enzyme (ACE) deletion (D) polymorphism have been associated with a high risk for coronary heart disease. Increased frequency of the 4 allele has also been reported in patients with late-onset of familial and sporadic Alzheimers disease (AD). The primary aim of this study is to examine the possible relationship between the ACE gene polymorphism and AD. The second aim of this study is to explore the relation of the ACE and apo-E genotypes with AD. Polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), and agarose gel electrophoresis techniques were used to determine the apo-E and ACE genotypes. The frequencies of ACE D and ACE insertion (I) allele among AD patients and controls were 55.7 percent versus 44.2 percent and 51.7 versus 48.2 percent, respectively. Apo-E allele frequencies in the AD group for 2, 3 and 4 were, 1.7 percent, 96.5 percent, and 1.7 percent, respectively. The apo-E allele frequencies of healthy groups for 2, 3 and 4 were 1 percent, 56 percent, and 1.7 percent, respectively. In conclusion ACE D and apo 4 allele were found to be more frequent in patients with Alzheimers disease than in the control group.