Selcuk Dasdemir

DNA Repair Genes in Parkinson's Disease

AIMS There is a growing interest in the understanding of a possible role of DNA repair systems in ageing and neurodegenerative diseases after DNA damage is observed in the brain of individuals affected by neurodegenerative diseases. In the light of these findings, we investigated whether DNA repair gene polymorphisms (XRCC1 Arg399Gln, XRCC3 Thr241Met XPD Lys751Gln, XPG Asp1104His, APE1 Asp148Glu, and HOGG1 Ser326Cys) account for an increased risk of Parkinsons disease (PD). METHODS The present analyses are based on 60 case subjects with PD and 108 unrelated healthy controls. Genotyping of DNA repair gene polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism. RESULTS We, for the first time, demonstrated the positive association of APE1, XRCC1, and XRCC3 DNA repair gene variants with PD risk. In our study, the frequencies of Glu/Glu genotype in APE1, Gln+ genotype of XRCC1, and Thr+ genotype of XRCC3 are higher in patients than in controls (p=0.028, p=0.002 and p=0.046, respectively). CONCLUSIONS In conclusion, our findings have suggested that APE1, XRCC1, and XRCC3 genetic variants may be a risk factor by increasing oxidative stress that might cause the loss of dopaminergic cells in the substantiata nigra and locus caeruleus, leading to abnormal signal transmittion, and ultimately, the development of PD. In addition, generation of reactive oxygen species from dopamine might affect the other DNA repair pathway proteins that we did not examine in the current study. Further studies with larger sample groups are necessary to clarify the role of DNA repair genes and the development of PD.

Association Between Polymorphisms of DNA Repair Genes and Risk of Schizophrenia

AIMS DNA repair gene polymorphisms have recently been implicated as potential pathogenic contributors of mental disorders. The aims of our study were to investigate the participation of nucleotide and base excision repair mechanisms in schizophrenia and to identify novel candidate DNA repair susceptibility genes. MATERIALS AND METHODS For these purposes, we genotyped apurinic/apyrimidinic endonuclease 1 (APE1), human 8-oxoguanine DNA N-glycosylase 1 (hOGG1), X-ray repair cross-complementation group 1 (XRCC1), XRCC3, xeroderma pigmentosum group D (XPD), and xeroderma pigmentosum group G (XPG) genes in schizophrenia subjects, their healthy relatives, and unrelated healthy controls. RESULTS Carriers of XRCC1 glutamine (Gln), XRCC3 threonine (Thr), hOGG1 cysteine (Cys), and XPD lysine (Lys) alleles were significantly more frequent among the cohort of schizophrenia patients than in controls. In contrast, the frequencies of XRCC3 methionine (Met) and XPD Gln allele carriers and hOGG1 serine (Ser)/Ser genotype carriers were higher among controls than in patients, suggesting a possible protective role for these gene variants against schizophrenia. Moreover, healthy relatives had significantly higher frequencies of XRCC3 Thr+ and XPD Lys+ genotypes than unrelated healthy controls. Minor allele frequencies, haplotypes, and overtransmitted alleles of DNA repair genes were also identified. CONCLUSION Our findings support XRCC1, XRCC3, hOGG1, and XPD as risk genes for schizophrenia and suggest that altered DNA repair functions may be involved in schizophrenia pathophysiology.

Cox-2 gene variants in migraine.

PURPOSE Migraine is a multifactorial and complex disorder, and any clear diagnostic marker to assess the status of the migraineurs has not been established, yet. Nonsteroidal anti-inflammatory drugs reduce production of prostanoids including PGE2 by inhibiting COX-1 and/or COX-2, and thereby suppress inflammatory pain in patients suffering from rheumatoid arthritis, osteoarthritis, and migraine. Thus, COX-2 regulation is important in the pathogenesis and treatment of migraine. We prospectively investigated COX-2-765G→C and COX-2-1195A→G gene polymorphisms which may account for an increased risk of migraine. METHODS The present analyses are based on 144 case subjects with migraine disease and 123 non-case subjects. Genotyping of COX-2 gene polymorphisms (COX-2-765G→C, COX-2-1195A→G) was detected by PCR-RFLP. RESULTS We, for the first time, demonstrated positive association of COX-2 gene variants with an increased risk for development of migraine. Carriers of COX-2-765 C+ genotype in controls were higher than in the patients (57.7% and 36.1% respectively; P<0.0001) and the frequencies of G+ genotype in patients were higher than in the controls (97.9% and 88.6% respectively; P: 0.002). In addition, frequencies of COX-2-765 GG and GC genotypes in patients were higher than in the controls (P<0.0001, P<0.0001 respectively). It seems that COX-2-765 G+ genotype had increased and COX-2-765 C+ genotype had decreased risk for migraine. In COX-2-1195 polymorphism only AG genotype was statistically significantly different in patients than in the controls (P<0.05). CONCLUSIONS Our findings have suggested that COX-2-765 G+ genotype could facilitate the development of migraine disease.

Chemokine gene variants in schizophrenia

ABSTRACT Background Chemokines are known to play a major role in driving inflammation and immune responses in several neuroinflammatory diseases, including multiple sclerosis, Alzheimer’s disease and Parkinson’s disease. Inflammation has also been implicated in the pathogenesis of schizophrenia. Aim We aimed to investigate a potential link between chemokines and schizophrenia and analyze the role of MCP-1-A2518G, SDF-1-3’A, CCR5-delta32, CCR5-A55029G, CXCR4-C138T and CCR2-V64I gene polymorphisms in the Turkish population. Methods Genotyping was conducted by PCR-RFLP based on 140 patients and 123 unrelated healthy controls to show the relation between chemokine gene variants and schizophrenia risk. Results Frequencies of CCR5-A55029G A genotypes and CCR5-A55029G AG genotypes were found higher in patients than the controls and even also CCR2-V64I WT: CCR5-A55029G A and CCR2-V64I 64I: CCR5-A55029G A haplotypes significantly associated according to Bonferroni correction. However, no significant association was found for any of the other polymorphisms with the risk of schizophrenia. Conclusions Our findings suggest that CCR5-A55029G polymorphisms and CCR2-V64I WT: CCR5-A55029G A and CCR2-V64I 64I: CCR5-A55029G A haplotypes might have association with schizophrenia pathogenesis.

−765 G→C and −1195 A→G Promoter Variants of the Cyclooxygenase-2 Gene Decrease the Risk for Preeclampsia

Cyclooxygenase-2 (COX-2) is the inducible isoenzyme of COX that leads to increased production of prostaglandins and thromboxane, the mediators of inflammation. Controversial data regarding COX levels or activities in the placentas of women with preeclampsia have led us to examine whether a single nucleotide polymorphism (SNP) in the COX-2 gene is associated with the onset of preeclampsia. Two polymorphisms in the promoter region of COX-2 gene were examined by the polymerase chain reaction and restriction fragment length polymorphism in 128 controls and 74 preeclamptic patients. Genotype distribution and allelic frequencies for -765G→C polymorphism of COX-2 gene were significantly different between patients and controls (p=0.000 and p=0.042, respectively). The odds ratio (OR) for preeclampsia risk associated to the -765G allelic variant was 4.07 (95% confidence interval [CI]: 0.89-18.56). The AA genotype of the -1195 A→G variant was present at a significantly higher frequency among all preeclamptic subjects (p=0.000 χ(2): 13.4, OR: 3.44, 95% CI: 1.74-6.77). A moderate linkage was observed between the -765G and -1195A variants (D(0): 0.201; r(2): 0.003). These findings suggest that SNPs, -765G→C and -1195 A→G, on the promoter region of COX-2 gene may reduce the risk of preeclampsia, possibly by affecting the rate of gene expression.

The Effect of PAI-1 Gene Variants and PAI-1 Plasma Levels on Development of Thrombophilia in Patients With Klinefelter Syndrome

Klinefelter syndrome (KS) is a common sex chromosome-related abnormality seen among men. KS negatively affects spermatogenesis and testosterone production. It increases the risk of thrombosis but its molecular mechanism has not been well described yet. Elevated PAI-1 is a risk factor for thrombosis. The rs1799889 polymorphism located in the promoter region of the PAI-1 gene was detected in patients with deep venous thrombosis. In this study, the PAI-1 gene variant and its plasma levels in KS patients were examined. Forty-one KS patients (47, XXY) and 50 age-matched healthy controls participated. DNA was isolated from peripheral blood and a real-time PCR method was used to detect known SNPs in the PAI-1 gene. In addition, PAI-1 plasma levels were measured by using ELISA method. There was no significant difference between PAI-1 gene polymorphisms of KS patients and controls (p > .05). The significant difference was observed in PAI-1 plasma levels between two groups (high PAI-1 plasma level in KS patients compared to controls). The patients’ group mean was 55.13 and control group mean in PAI-1 level was 29.89 ng/ml (p = .020). Clinical features related to thromboembolism especially varicose veins were detected in KS patients frequently (p = .04). These results suggest that thromboembolism related to clinical features is seen more frequently in cases with KS, but it may not be dependent only on the PAI-1 gene polymorphism structure.