Protective role of interlekin-1 alpha gene polymorphism in Chinese Han population with sporadic Parkinson's disease

Parkinson's disease is the second most common neurodegenerative disorders after Alzheimer's disease in the elderly. Abundant evidence showed that proinflammatory factors were involved in the pathogenesis of sporadic Parkinson's disease (SPD). Interleukin-1 (IL-1) is a cytokine that plays an important role in neurodegenerative disease. Previous association studies between genetic polymorphisms of IL-1 alpha and PD have showed conflicting results and no such study was done in Chinese. We recruited 533 SPD patients and 530 controls in Chinese Han population to investigate the association of IL-1alpha C-899T allele and risk for PD. Real-time PCR was used to detect the polymorphism, and multiple logistic regression, Chi square test and survival analysis were performed to explore the association. The distribution of IL-1alpha alleles was significantly different between the cases and controls, and the T allele was associated with a reduced risk of PD (OR: 0.72, 95%CI: 0.54-0.97, rho = 0.033). However, survival analysis showed that the T allele did not delay the onset age of PD (T allele vs. non-T allele log rank: chi2 = 0.14, p = 0.70). Our data suggest that the T allele carriers have less inclination to have PD in Chinese Han population.     

Lack of association of polymorphism in miRNA-196a2 with Parkinson's disease risk in a Chinese population

MicroRNAs (miRNAs) are a new class of non-protein coding RNA molecules, which participate in diverse biological pathways. We hypothesized that miRNA-196a2 polymorphism is associated with the risk of Parkinson's disease (PD) in a Chinese population. In a case-control study of 549 PD patients and 736 control subjects frequency matched by age and gender, we genotyped the single-nucleotide polymorphism (SNP) rs11614913 (T>C) in miRNA-196a2, whose target mRNA was alpha-synuclein, and assessed its association with risk of PD by TaqMan Genotyping method. No association was found for the miR-196a2 rs11614913 CT/CC genotype (odds ratio (OR), 0.879, 95% confidence interval (CI), 0.681-1.135 for CT genotype; OR, 1.085, 95% CI, 0.793-1.484 for CC genotype) with risk of PD, compared with the TT genotype. These results suggest that SNP rs11614913 in miRNA-196a2 may not contribute to the susceptibility to PD.     

Mitochondrial translation initiation factor 3 gene polymorphism associated with Parkinson's disease

Mitochondrial dysfunction occurs early in late-onset sporadic Parkinson's disease (PD), but the mitochondrial protein network mediating PD pathogenesis is largely unknown. Mutations in the mitochondrial serine-threonine kinase PINK1 have recently been shown to cause the early-onset autosomal recessive PARK6 variant of PD. We have now tested a candidate interactor protein of PINK1, the mitochondrial translation initiation factor 3 (MTIF3) for involvement in PD pathogenesis. In two independent case-control collectives, the c.798C>T polymorphism of the MTIF3 gene showed allelic association with PD, with a maximal significance of p=0.0073. An altered function of variant MTIF3 may affect the availability of mitochondrial encoded proteins, lead to oxidative stress and create vulnerability for PD.     

No association between polymorphism of serotonin transporter gene and depression in Parkinson's disease in Chinese

Depressive symptoms affect 40% to 50% of Parkinson's disease (PD) patients, and adversely impact their quality of life. The decrease of serotonin (5-HT) in the synaptic cleft is commonly considered as the cause of depression. The reuptake of 5-HT released into the synaptic cleft is mediated by the 5-HT transporter (5-HTT). Many studies have focused on the relationship between the 5-HTT-linked polymorphic region (5-HTTLPR) and depression. The present study is to investigate the association between the polymorphisms in the promoter of the 5-HTT gene (including 5-HTTLPR and rs25531), which determine either a higher or lower 5-HT uptake, and risk for depression of PD. Three hundred six idiopathic PD patients were recruited randomly from hospital clinic and the Center for Epidemiological Studies Depression Scale (CES-D) was used as the diagnosis or rating scale for depression. Polymerase Chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used and the patients’ genotypes were divided as L_A, L_G, S_A, and S_G. We found no evidence for an association between variants of 5-HTTLPR and rs25531 alleles, and depressive symptoms in Chinese PD patients.     

Dinucleotide repeat polymorphism in the third intron of the NRAMP2/DMT1 gene

Nramp1 (natural resistance-associated macrophage protein 1), encoding a polytropic integral membrane protein, was isolated as a candidate of the mouse Lsh/Ity/Bcg locus, which regulates macrophage activation for antimicrobial activity against intracellular pathogens. The NRAMP2 gene was cloned from human genome as a homologue of NRAMP1. We found a polymorphic dinucleotide repeat in the third intron of the NRAMP2 gene. This polymorphism will be a useful genetic marker to study disease associated with susceptibility to infection with intracellular pathogens. Received: August 13, 1999 / Accepted: August 19, 1999     

Extremely rare incidence of the UBQLN1 polymorphism (UBQ-8i) in Taiwan Chinese with Alzheimer's disease

Recently, a single nucleotide polymorphism (SNP, A → G) in intron 8 of UBQLN 1 at the rs12344615 site (UBQ-8i) on chromosome 9q22 was associated with a higher risk of late-onset Alzheimer's disease (AD). Here, we aimed to investigate whether an association exists between the UBQ-8i polymorphism and AD in Taiwan Chinese. Initially, we included 100 late-onset AD patients and 100 gender- and age-matched non-demented (ND) control participants. The UBQ-8i polymorphism site was successfully determined in 91 AD and 96 ND individuals using the dye terminator nucleotide sequencing technique. Among the 187 participants, we did not detect any subject carrying the G allele. This finding is in agreement with the report listed in the NCBI SNP Reference Assembly, which states that <1% of Asians carry this SNP. The APOE ?4 allele, an established AD genetic risk factor, was overrepresented in the AD cohort. We conclude from these results that the UBQ-8i polymorphism of the UBQLN1 gene is extremely rare in Taiwan Chinese and unlikely to play a significant role in the risk of AD in Taiwan Chinese.     

Association of GST M1 null polymorphism with Parkinson's disease in a Chilean population with a strong Amerindian genetic component

We have studied the association of a null mutation of Glutathione Transferase M1 (GST M1*0/0) with Parkinson's disease (MIM 168600) in a Chilean population with a strong Amerindian genetic component. We determined the genotype in 349 patients with idiopathic Parkinson's disease (174 female and 175 male; 66.84+/-10.7 years of age), and compared that to 611 controls (457 female and 254 male; 62+/-13.4 years of age). A significant association of the null mutation in GST M1 with Parkinson's disease was found (p=0.021), and the association was strongest in the earlier age range. An association of GSTM1*0/0 with Parkinson's disease supports the hypothesis that Glutathione Transferase M1 plays a role in protecting astrocytes against toxic dopamine oxidative metabolism, and most likely by preventing toxic one-electron reduction of aminochrome.     

Correlation of tau gene polymorphism with age at onset of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease and its prevalence increases with age. The microtubule-associated protein tau (MAPT) is thought to be implicated in the pathogenesis of PD. Association of the MAPT H1 haplotype with PD in Caucasians has been extensively studied, however, the results were inconsistent. In this study, we investigated whether MAPT gene variants contribute to the pathogenesis process including the age at onset in Japanese PD. Promoter region of MAPT gene was analyzed to find polymorphisms in Japanese population. Two single nucleotide polymorphisms (SNPs), C-639T and Del-568TIns, in promoter region were found. C-639T was novel. Unlike Caucasians, the −226C and −45A alleles consisting of the H1 haplotype were monomorphic in Japanese population. Association analysis was performed using 240 PD and 191 controls in these SNPs. No significant association was observed between these SNPs and PD. Haplotype analysis also showed no significant association (P = 0.72). However, the age at onset showed significant correlation with the genotypes of Del-568TIns in PD samples when analyzed by Kendall rank correlation test (Kendall tau = −0.098, P = 0.0243). These results suggested that MAPT gene variants may modify the pathogenesis process of PD.     

Vitamin D receptor gene polymorphism and its association with Parkinson's disease in Chinese Han population

Vitamin D plays an important role in neurodegenerative disorders as a crucial neuro-immunomodulator, and accumulating data have provided evidence for that vitamin D receptor (VDR) gene is a candidate gene for susceptibility to Parkinson's disease (PD). In this study, we performed a case-control study to demonstrate whether the risk for the development of onset of sporadic PD might be influenced by VDR gene polymorphisms in a Chinese cohort. Two hundred and sixty PD patients and 282 matched-healthy controls were genotyped for two representative single nucleotide polymorphisms (SNPs) in VDR gene (FokI C/T and BsmI G/A) by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis in. Results from our study revealed that FokI C allele carriers were likely to associate with an increased risk of PD (P = 0.004) as well as early-onset PD (EOPD) (P = 0.010). Moreover, the frequency of FokI C allele was significantly increased in PD group and late-onset PD (LOPD) group relative to the control groups respectively (P = 0.023 and P = 0.033, respectively). For BsmI polymorphisms, no significant difference in genotype or allele distribution was found between PD patients and the controls, as well as gender- and age-related differences between PD patients and the controls subgroup. This study demonstrated a possible association between the VDR FokI T/C polymorphism and PD, indicating that VDR polymorphisms may well change genetic susceptibility to sporadic PD in a Han Chinese population.     

Serotonin transporter polymorphic region 5-HTTLPR modulates risk for Parkinson's disease

The association between the serotonin transporter gene (SLC6A4) polymorphisms, that is, 5-HTTLPR and rs25531, and Parkinson's disease (PD) remains to be further defined. We investigated this relationship in a Chinese cohort that comprised 504 PD patients and 504 controls. A total of 8 haplotypes and 14 genotypes of SLC6A4 were found in this population including a new variant of 5-HTTLPR, that is, 20_G. Our results presented that 5-HTTLPR was associated with an aggravated risk for PD (p = 0.005). The rs25531 alone is not associated with PD susceptibility. However, in a sub-classification based on the impact of 5-HTTLPR and rs25531 on 5-HTT expression, we observed a significant difference in 5-HTT expressing distribution in the cohort, accompanied by an apparently lower level of 5-HTT high expressing group, that is, the L_AL_A genotype, in the PD patients. Taken together, our data provide novel insight in support that the SLC6A4 polymorphisms, particularly 5-HTTLPR, and the serotonergic system are associated with PD etiology.     

Interactions between rs5498 polymorphism in the ICAM1 gene and traditional risk factors influence susceptibility to coronary artery disease

Coronary artery disease (CAD) depends on multiple genetic and environmental factors. Adhesion molecules are markers of endothelium dysfunction. Intercellular adhesion molecule-1 (ICAM-1) interacts with leukocyte integrins and promotes atherosclerotic process at the surface of endothelial cells. The aim of the study was to assess the association between ICAM1 rs5498 polymorphism and CAD and to establish whether there are any interactions between this polymorphism and traditional risk factors in determining the risk of CAD. We studied 191 cases with angiographically documented CAD and 203 controls with no signs of cardiovascular diseases. The ICAM1 polymorphism was genotyped using PCR–RFLP method. Data were analyzed with the STATISTICA 7.1 and EpiInfo 6 softwares. We did not observe significant differences in the distribution of genotypes and alleles of rs5498 between cases and controls. We only found a tendency to a higher prevalence of G allele carriers (AG + GG) in patients compared to controls (68 vs. 64%, P = 0.399). A synergistic effect of G allele carrier-state and smoking that had influenced the risk of CAD [synergy index multiplicative (SIM = 2.09)] was observed. Smoking carriers of G allele compared to non-smoking AA were more prevalent in CAD group (39.8%) than among controls (13.3%, P < 0.0001, OR 4.81). Moreover, there was also a synergistic effect between G allele carrier-state and an elevated level of triacylglycerols (TG) (SIM = 1.28) increasing the risk of CAD. There is a synergistic interaction between rs5498 genotype and smoking that increases the risk of CAD.     

Single nucleotide polymorphisms in base-excision repair genes hOGG1, APE1 and XRCC1 do not alter risk of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with a poorly understood etiology. There is considerable evidence that oxidative stress occurs in AD and increased DNA damage has been found in brain tissues and leukocytes of AD patients. Base excision repair (BER) is the major pathway responsible for removing oxidative DNA damage. Polymorphisms in DNA-repair genes have been associated with the increased risk of several age-related disorders including various types of cancer and could also be related to the etiology of AD. We conducted a case-control study including 91 patients with AD and age- and sex-matched 93 control subjects to examine the role of single nucleotide polymorphisms of BER genes, hOGG1 (Ser326Cys), APE1 (Asp148Glu) and XRCC1 (Arg280His and Arg399Gln) as a risk factor for AD. The frequencies of the hOGG1-Ser326Cys, APE1-Asp148Glu and XRCC1-Arg280His and XRCC1-Arg399Gln variant alleles in our control group were 0.23, 0.31, 0.10 and 0.33, respectively. No significant association was observed between the variant alleles of hOGG1-Ser326Cys (OR=1.32, 95% CI=0.83-2.11), APE1-Asp148Glu (OR=1.08, 95% CI=0.70-1.68), XRCC1-Arg280His (OR=0.53, 95% CI=0.24-1.14) and XRCC1-Arg399Gln (OR=1.05, 95% CI=0.68-1.63) and AD. Our results suggest that the polymorphic variants of these BER genes are not independent risk factors for AD.     

Analysis of LINGO1 (rs9652490) polymorphism in sporadic Parkinson's disease in a Polish population,and a meta-analysis

Recently, a variant in LINGO1 (also denominated as LRRN6A) rs9652490:A>G gene has been found to associate with increased risk of essential tremor (ET). Because ET and Parkinson's disease (PD) may be ethiologically related, we proceeded to conduct an analysis of the SNP in PD population. In the current study LINGO1 rs9652490:A>G polymorphism was evaluated in a cohort of 162 Polish patients diagnosed with PD and 177 controls by means of MALDI-TOF mass spectrometry. Any significant differences in rs9652490 genotype or allele frequencies between the studied groups were noted. Our findings demonstrate that LINGO1 SNP (rs9652490) is not associated with sporadic PD in our Polish cohort. A meta-analysis of the available data suggests protective role of rs9652490GG genotype (OR 0.70, 95% CI: 0.51–0.96, p = 0.028).     

NEDD9 rs760678 polymorphism and the risk of Alzheimer's disease: A meta-analysis

The NEDD9 rs760678 polymorphism has been extensively investigated for association to Alzheimer's disease (AD), however, results of different studies have been inconsistent. The objective of this study is to assess the relationship of NEDD9 rs760678 polymorphism and AD risk by using meta-analysis. Systematic searches of electronic databases Pubmed and Embase, as well as hand searching of the references of identified articles were performed. Statistical analyses were performed using software Revman 4.2 and STATA 11.0. A total of 4436 cases and 4420 controls in 11 case–control studies were included. The results indicated that the homozygote GG had a 13% decreased risk of AD, when compared with the C allele carriers (CC + CG) (OR = 0.87, 95%CI = 0.77–0.99, P = 0.04 for GG vs. CG + CC). In the subgroup analysis by ethnicity, significant decreased risk was associated with homozygote GG or G allele carriers in Caucasians (OR = 0.84, 95%CI = 0.74–0.96, P = 0.008 for GG vs. CG + CC; OR = 0.79, 95%CI = 0.69–0.91, P = 0.001 for GG vs. CC; OR = 0.90, 95%CI = 0.84–0.96, P = 0.002 for G vs. C), but not in Asians. This meta-analysis suggests that the GG genotype of NEDD9 rs760678 polymorphism would be a protective factor for AD in Caucasians but not in Asians. To further evaluate the effect of gene–gene and gene–environmental interactions between NEDD9 rs760678 polymorphism and the risk of AD, more studies with larger number of subjects are required.     

Interleukin-10 promoter polymorphisms in Chinese patients with Parkinson's disease

Interleukin-10 (IL-10), an important anti-inflammatory cytokine, may influence the risk for the development of onset of sparadic Parkinson's disease (PD) in the inflammatory process. In this study, two DNA polymorphisms at IL-10 gene promoter (-819 T/C and -592 A/C) were examined in 355 sporadic PD patients and 200 healthy controls in Han Chinese Population. For both polymorphisms, no significant difference in genotype or allele distribution was found between PD patients and the controls. For -819 T/C polymorphisms, there was significant difference in genotype distribution between EOPD (EOPD, <50 years of age) patients and each healthy-matched control subgroup (P=0.011), as well as between female PD patients and each healthy-matched control subgroup (P=0.024), For -592 A/C polymorphisms, there were no significant gender- and age-related differences in genotype distribution between PD patients and the controls subgroup. Results from our study revealed that the IL-10 promoter (-819 and -592) polymorphism is not a risk factor of sporadic Parkinson's disease, but the IL-10 promoter -819 polymorphism is a risk factor of EOPD and female PD patients in Han Chinese population.     

Alzheimer's disease and Parkinson's disease genome-wide association study top hits and risk of Parkinson's disease in Korean population

Alzheimer's disease (AD) and Parkinson's disease (PD) have overlapping clinical and pathological features, suggesting a common pathway for these 2 neurodegenerative disorders. Here we investigated the association of both AD and PD GWAS top hits with PD susceptibility. We selected 25 single nucleotide polymorphisms (SNPs) in 9 genes (ABCA7, APOE, BST1, CLU, CR1, LRRK2, PARK16, PICALM, and SNCA) that were genotyped in 1036 PD case patients and 1208 controls. Case patients and controls were all ethnic Koreans. Logistic regression analysis was performed to calculate age- and sex-adjusted odds ratios. None of the AD-susceptibility loci (ABCA7, APOE, CLU, CR1, and PICALM) showed statistically significant association with PD susceptibility. In contrast, we replicated associations of SNCA, LRRK2, BST1, and PARK16 with PD susceptibility in Koreans. Of those, the SNCA SNP rs11931074 showed the most significant association with PD susceptibility (adjusted odds ratio = 1.48; 95% confidence interval = 1.31–1.67; p = 2.20E-10). In a logistic regression analysis with SNPs coded under an additive model, there was no significant genetic interaction between the LRRK2 and the PARK16 locus gene RAB7L1 in PD risk. Our results confirm the associations of SNCA, LRRK2, BST1, and PARK16 with PD susceptibility and fail to show significant associations of AD genome-wide association study (GWAS) top hits with PD susceptibility in a Korean population.     

VEGF polymorphisms and serum VEGF levels in Parkinson's disease

Accumulated data within the recent years demonstrate that reduced levels of VEGF which is a well known angiogenic molecule might cause neurodegeneration in part by impairing neural tissue perfusion, vasoregulation and normal functioning of perivascular autonomic nerves. Additionally, VEGF has been reported to support neuroprotection in dopaminergic neurons by indirect and direct mechanisms and suppress apoptosis in dopaminergic neurons in vitro. The aim of the current study is first to demonstrate whether there is an association between the three common VEGF polymorphisms (−2578C/A, −634C/G and 936C/T) in the VEGF gene and idiopathic Parkinson's disease (IPD) which is a neurodegenerative disease caused by the progressive degeneration of nigrostriatal dopaminergic neurons, and second to see if the serum levels of VEGF is reduced in the patients with IPD. We screened the genotype and allele frequencies of three common functional polymorphisms of VEGF, namely −2578C/A, −634C/G and 936C/T in DNA samples of 126 patients with IPD and healthy control subjects and also we compared the median serum levels of VEGF between these two groups. No association was found between the inspected VEGF polymorphisms and IPD and also no difference was found between the serum VEGF levels of both groups. The current study failed to support the hypothesis that VEGF polymorphisms and/or reduced serum VEGF levels are likely contributors to the neurodegenerative process in IPD.     

Significance and confounders of peripheral DJ-1 and alpha-synuclein in Parkinson's disease

DJ-1 and α-synuclein are leading biomarkers for Parkinson's disease diagnosis and/or monitoring disease progression. A few recent investigations have determined DJ-1 and α-synuclein levels in plasma or serum, a more convenient sample source than cerebrospinal fluid; but the results were variable or even contradictory. Besides limitations in detection technology and limited number of cases in some studies, inadequate control of several important confounders likely has contributed to these inconsistent results. In this study, the relative contribution of each blood component to blood DJ-1 and α-synuclein was evaluated, followed by quantification of plasma levels of both markers in a larger cohort of patients/subjects (∼300 cases) whose cerebrospinal fluid DJ-1 and α-synuclein levels have been determined recently. The results demonstrated that the DJ-1 and α-synuclein in blood resided predominantly in red blood cells (>95%), followed by platelets (1–4%), white blood cells and plasma (≤1%), indicating that variations in hemolysis and/or platelet contamination could have a significant effect on plasma/serum DJ-1 and α-synuclein levels. Nonetheless, after adjusting for the age, although there was a trend of decrease in DJ-1 and α-synuclein in patients with Parkinson's or Alzheimer's disease compared with healthy controls, no statistical difference was observed in this cohort between any groups, even when the extent of hemolysis and platelet contamination were controlled for. Additionally, no correlation between DJ-1 or α-synuclein and Parkinson's disease severity was identified. In conclusion, unlike in cerebrospinal fluid, total DJ-1 or α-synuclein in plasma alone is not useful as biomarkers for Parkinson's disease diagnosis or progression/severity.     

Regulation of DMT1 on Bone Microstructure in Type 2 Diabetes

Diabetic osteoporosis is gradually attracted people''s attention. However, the process of bone microstructure changes in diabetic patients, and the exact mechanism of osteoblast iron overload are unclear. Therefore, the present study aimed to explore the function of DMT1 in the pathological process of diabetic osteoporosis. We build the type two diabetes osteoporosis models with SD rats and Belgrade rats, respectively. Difference expression of DMT1 was detected by using the method of immunohistochemistry and western blotting. Detection of bone microstructure and biomechanics and iron content for each group of samples. We found that DMT1 expression in type 2 diabetic rats was higher than that in normal rats. The bone biomechanical indices and bone microstructure in the rat model deficient in DMT1 was significantly better than that in the normal diabetic model. The loss of DMT1 can reduce the content of iron in bone. These findings indicate that DMT1 expression was enhanced in the bone tissue of type 2 diabetic rats, and plays an important role in the pathological process of diabetic osteoporosis. Moreover, DMT1 may be a potential therapeutic target for diabetic osteoporosis.     

Genetic variation in BIN1 gene and Alzheimer's disease risk in Han Chinese individuals

Genome-wide association studies have identified the bridging integrator 1 (BIN1) gene as the most important genetic susceptibility locus in late-onset Alzheimer's disease (LOAD) after apolipoprotein E for individuals of European ancestry. To further characterize this association and to isolate the variants within BIN1 contributing to LOAD in Han Chinese individuals, we conducted a 2-step design study in our cohort of 1133 LOAD patients and 1159 control subjects. Sequencing analysis identified 44 variants within BIN1. Follow-up genotyping analysis revealed that a novel missense mutation P318L appeared to exert risk effect for development of LOAD; and rs67327804 was also significantly associated with LOAD risk even after adjusting for age, gender, and apolipoprotein E ε4 status. Haplotype analysis confirmed that the “GA” haplotype derived from single-nucleotide polymorphisms in rs67327804 and rs1060743 showed a 1.4-fold increased risk of LOAD. Our findings provided the first independent evidence that variants in BIN1 were significantly associated with LOAD in Han Chinese individuals.