Butyrylcholinesterase K variant is genetically associated with late onset Alzheimer's disease in Northern Ireland

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that has been associated, sometimes controversially, with polymorphisms in a number of genes. Recently the butyrylcholinesterase K variant (BCHE K) allele has been shown to act in synergy with the apolipoprotein E epsilon4 (APOE epsilon4) allele to promote risk for AD. Most subsequent replicative studies have been unable to confirm these findings. We have conducted a case-control association study using a clinically well defined group of late onset AD patients (n=175) and age and sex matched control subjects (n=187) from the relatively genetically homogeneous Northern Ireland population to test this association. The BCHE genotypes of patients were found to be significantly different from controls (chi(2)=23.68, df=2, p<0.001). The frequency of the K variant allele was also found to differ significantly in cases compared to controls (chi(2)=16.39, df=1, p<0.001) leading to an increased risk of AD in subjects with this allele (OR=3.50, 95% CI 2. 20-6.07). This risk increased in subjects 75 years and older (OR=5. 50, 95% CI 2.56-11.87). At the same time the APOE epsilon4 associated risk was found to decrease from 6.70 (95% CI 2.40-19.04) in 65-74 year olds to 3.05 (95% CI 1.34-6.95) in those subjects 75 years and older. However, we detected no evidence of synergy between BCHE K and APOE epsilon4. The results from this study suggest that possession of the BCHE K allele constitutes a significant risk for AD in the Northern Ireland population and, furthermore, this risk increases with increasing age.     

Association between apolipoprotein E polymorphism and Alzheimer disease in Tehran, Iran

Epsilon 4 allele of apolipoprotein E (APOE-epsilon4) is a major risk factor for Alzheimer's disease (AD). The association of APOE allele frequencies with AD remains unknown in developing countries. We examined the frequency of APOE alleles in 105 patients with AD and 129 cognitively normal subjects of similar age and sex (control group), in Tehran, Iran. The APOE-epsilon4 allele frequency was significantly higher in the AD subjects than in the control group (21% versus 6.2%, p < 0.001). In addition, the OR for APOE-epsilon4 heterozygous and homozygous subjects were 3.2 (p = 0.001) and 12.75 (p = 0.01), respectively. The OR was not uniform across age groups. The AD subjects carrying one or two APOE-epsilon4 allele showed earlier age-at-onset (p < 0.001). These data suggest that the APOE-epsilon4 allele increase the risk for AD in Tehran population in a dose and age-dependent manner. Although the APOE-epsilon2 allele frequency was lower in the AD subjects than in the control group (0.95% versus 2.7%, p = 0.15), APOE-epsilon2 was not associated with the onset of AD in Tehran's population. The OR for epsilon2 allele in AD subjects was 0.34 (p = 0.21). The genotype frequencies for epsilon3, epsilon4, and epsilon2 alleles in control subjects were 91.2, 6.1, and 2.7%, respectively. These values were similar to that reported for Turkish, Greece, Japanese, Spanish, and Moroccan populations, but they were significantly different from the reported values for the other ethnic populations. This observation emphasizes the importance of geographical location and ethnical background of the subjects in the study of APOE genotypes and their association with AD.     

Exploration of 16 candidate genes identifies the association of IDE with Alzheimer's disease in Han Chinese

Alzheimer's disease (AD) has a complex pattern of inheritance and many genes have recently been reported to contribute to the disease susceptibility. We selected 106 SNPs within 16 candidate genes and performed a multistage association study using 4 sample sets consisting of 731 AD patients and 738 control subjects to identify genetic factors for AD in Han Chinese. A single nucleotide polymorphism (SNP) in the insulin degrading enzyme gene (IDE), rs3781239, showed a significant association with AD. The C allele increased the risk of AD 1.72-fold than the G allele (odds ratio [OR] = 1.72, 95% confidence interval [CI] = 1.17-2.53, p = 0.006) and CC carriers had a 4.89-fold higher risk for AD than that of the carriers with CG and GG genotypes (odds ratio = 4.89, 95% CI = 1.85-12.91, p = 0.001). Moreover, the CC genotype was significantly associated with earlier age at onset (p = 0.001, hazard ratio [HR] = 2.09, 95% CI = 1.38-3.18). Our data suggest that the polymorphism of IDE is associated with susceptibility to Alzheimer's disease in Han Chinese.     

Association between apolipoprotein E polymorphism and serum lipid and apolipoprotein levels with Alzheimer's disease

We have recently demonstrated that apolipoprotein E (APOE)-varepsilon4 allele is a risk factor for Alzheimer disease (AD) in Tehran, Iran. The current study specifically aimed to examine whether APOE polymorphism in association with serum lipids-apolipoprotein level is a risk factor for AD in a population from Tehran, Iran. APOE polymorphism and plasma lipids, apoA1, apoB and lipoprotein (a) (Lp(a)) levels were determined in 94 AD patients and 111matched controls. Our study demonstrated a significant association between APOE polymorphism and the level of plasma lipids and apolipoprotein with AD in this population. The AD subjects had significantly lower apoA1 (p<0.001) and HDL-C (p<0.01) and higher apoB (p=0.01) and LDL-C (p=0.02) levels than that of the control group. The AD subjects carrying APOE-varepsilon4 allele had lower plasma apoA1 (t=5.2, p<0.002) and HDL-C level (t=2.7, p=0.01) but had higher plasma apoB (t=-5.4, p<0.002), LDL-C (t=-4.6, p=0.005) and total cholesterol (TC) (t=-2.7, p=0.01) than that of the non APOE-varepsilon4 carriers. These results indicated that AD patients with APOE-varepsilon4 allele has a distinct plasma lipid profile and carrier of this allele with low levels of apoA1 and HDL-C may be more susceptible to AD.     

Screening of two mutations at exon 3 of the apolipoprotein E gene (sites 28 and 42) in a sample of patients with sporadic late-onset Alzheimer's disease

The search for further variation at the APOE gene in a sample of patients with sporadic late-onset Alzheimer's disease (AD) and related controls revealed two different mutations in the exon 3 of the gene. One, the Leu28-->Pro, always found on an APOE e(*)4 allele, was present in five of the 94 patients and in 1 of the 157 controls. The other, Thr42-->Ala, found on an e(*)3 allele, was observed in only one AD patient, who also carried the Leu28-->Pro, but in none of the controls.In the AD patient group the allele e(*)4(-), corresponding to Leu28-->Pro, showed a frequency of 0.027, compared with only 0.003 in the controls. Compared to E3/3 and E3/2 genotypes, the risk of developing AD associated with the genotypes carrying the e(*)4 allele, the well-established risk allele for AD onset, was observed to be high (OR=3.16; 95% CI=1.62-6.20; P=0.0009), but the risk associated with genotypes carrying the Leu28-->Pro mutation was higher still (OR=10.95; 95% CI=1.25-95.75; P=0.015). The higher risk associated with this mutation was assessed by meta-analysis carried out using the data of three patient groups from a previously published study Kamboh et al. and from our study. The results indicated that, compared with all the other APOE genotypes, those carrying the Leu28-->Pro mutation were at a substantially higher risk of developing AD (OR=4.25; 95% CI=1.21-14.97).     

Genetic association of the APP binding protein 2 gene (APBB2) with late onset Alzheimer disease

Alzheimer disease (AD) is a complex neurodegenerative disorder predisposed by multiple genetic factors. Mutations in amyloid beta precursor protein (APP) are known to be associated with autosomal dominant, early onset familial AD and possibly also late onset AD (LOAD). A number of genes encoding proteins capable of binding to APP have been identified, but their contribution to AD pathobiology remains unclear. Conceivably, mutations in these genes may play a role in affecting AD susceptibility, which appears to be substantiated by some genetic studies. Here we report results of the first genetic association study with APBB2, an APP binding protein (also known as FE65L), and LOAD, in three independently collected case-control series totaling approximately 2,000 samples. Two SNPs were significantly associated with LOAD in two sample series and in meta-analyses of all three sample sets (for rs13133980: odds ratio [OR](hom)=1.36 [95% CI: 1.05-1.75], OR(het)=1.32 [95% CI: 1.04-1.67], minor allele frequency=43%, P=0.041; and for hCV1558625: OR(hom)=1.37 [95% CI: 1.06-1.77], OR(het)=1.02 [95% CI: 0.82-1.26], minor allele frequency=48%, P=0.026). One of these SNPs, located in a region conserved between the human and mouse genome, showed a significant interaction with age of disease onset. For this marker, the association with LOAD was most pronounced in subjects with disease onset before 75 years of age (OR(hom)=2.43 [95% CI: 1.61-3.67]; OR(het)=2.15 [95% CI: 1.46-3.17]; P=0.00006) in the combined sample set. Our data raise the possibility that genetic variations in APBB2 may affect LOAD susceptibility.     

APOE, ACT and CHRNA7 genes in the conversion from amnestic mild cognitive impairment to Alzheimer's disease

We have investigated whether the -86 C/T promoter polymorphism in CHRNA7 gene, the signal peptide polymorphism of the alpha1-antichymotripsin (ACT) gene or the APOE genotype are associated with an increased risk of mild cognitive impairment (MCI) or affect the risk of evolution to Alzheimer's disease (AD). We have followed up 89 patients with initial diagnoses of amnestic MCI for 49 months. Patients were separated into three groups: 27 subjects who remained with MCI, 40 that converted to AD before 20 months and 22 that converted to AD after. To assess the risk associated to each genotype a control group (n=90) without cognitive impairment was included. APOE4 allele was associated with an increased risk of MCI (OR: 6.04, 95% CI: 2.76-3.23; p<0.001) but did not have an effect on the probability of evolving AD. ACT or CHRNA7 genotypes were not associated with MCI but both appear to modify the risk of progression to dementia in opposing manners: ACT polymorphism increasing the risk to evolve to AD before 20 months (HR=2.03; 95% CI: 1-4.6; p=0.06) and CHRNA7 polymorphism protecting from evolution to dementia. Cox regression model demonstrated that ACT genotype confers a higher risk of rapid evolution to dementia than age or years of schooling. We conclude that APOE is a risk gene for amnestic MCI and that ACT and CHRNA7 may act in these patients as modifier genes for the time of progression to AD.     

Using CSF biomarkers to replicate genetic associations in Alzheimer's disease

Defining cases and controls on the basis of biomarkers rather than clinical diagnosis may reduce sample sizes required for genetic studies. The aim of this study was to assess whether characterizing case/control status on the basis of cerebrospinal fluid (CSF) profile would increase power to replicate known genetic associations for Alzheimer's disease (AD). Independent of clinical diagnosis, Alzheimer's Disease Neuroimaging Initiative (ADNI) subjects with 2 CSF biomarkers for AD (Aβ1-42 < 192 pg/mL and tau phosphorylated at threonine 181 (p-tau) > 23 pg/mL, "CSF-positive") were compared with those without CSF evidence for AD (Aβ1-42 > 192 pg/mL and 181-phosphorylated tau < 23 pg/mL, "CSF-negative"). Minor allele frequency (MAF) and odds ratios (ORs) between these 2 groups were calculated for 7 single-nucleotide polymorphisms (SNPs) of interest. Two hundred thirty-two individuals were CSF-positive and 94 CSF-negative. There were no differences in age (74.7 ± 7.2 vs. 75.0 ± 6.5 years, p = 0.7), but significant differences in Mini Mental State Examination (MMSE) (25.9 ± 2.6 vs. 28.2 ± 1.7, p < 0.001) between the CSF-positive and CSF-negative groups. Significant differences in MAF (p < 0.05, uncorrected) were seen for CR1 (rs1408077; OR, 1.59; 95% confidence interval [CI], 1.01-2.49), PICALM (rs541458; OR, 0.68, 95% CI, 0.47-0.98), TOMM40 (rs2075650; OR, 4.30; 95% CI, 2.61-7.06); and possession of 1 or more APOE ε4 alleles (OR, 9.84; 95% CI, 5.48-17.67). These results suggest that using biomarkers of AD pathology to define case and control status may increase power in genetic association studies.     

Mitochondrial haplogroup H and Alzheimer's disease--is there a connection?

We evaluated the involvement of the major Caucasian-specific mitochondrial haplogroups (H, I, J, K, T, U, V, W and X), haplogroup clusters (HV, UK, TJ, IWX) and two functional mtSNPs (4216, 4917) in the pathogenesis of Alzheimer's disease (AD) in the Polish population. The frequency distribution of mtDNA haplogroups was non-randomly associated with APOE4 status (chi(2)=73.17, df=1, p<0.0001, OR=5.97, 95% CI 3.90-9.12), however, no haplogroup-specific neutralizing of the APOE4 allele influence was detected. Multivariate analysis suggested the opposite-APOE4 status could modulate the effect of mtDNA haplogroups. We found that HV cluster is significantly associated with the risk of AD, regardless of the APOE4 status (OR=1.59, 95% CI, 1.04-2.44, p=0.032). Contrary to the previous studies, we report no evidence for the involvement of haplogroup U, K, J or T in AD risk. We conclude that further analysis of subtypes of haplogroup H would be necessary to decipher the relation of HV cluster with AD.     

Association of RFC1 A80G and MTHFR C677T polymorphisms with Alzheimer's disease

We examined polymorphisms in reduced folate carrier gene (RFC1) and methylenetetrahydrofolate reductase gene (MTHFR) for association with sporadic AD (SAD) in Chinese population. Significant associations of RFC1 A80G G allele and GG genotype with SAD (p=0.008, OR=1.312, 95%CI=1.072-1.605, and p=0.042, OR=1.383, 95%CI=1.012-1.890) were found. Further stratification of total samples by APOE epsilon4 carrier status, age/age at onset and gender revealed that RFC1 A80G G allele was an APOE epsilon4-independent risk factor for late-onset AD, and it might increase the risk of AD in females. No significant associations of MTHFR C677T allele and genotype with AD were observed in total samples, but significant associations of T allele and TT genotype with AD (p=0.031, OR=1.586, 95%CI=1.042-2.414, and p=0.028, OR=2.250, 95%CI=1.074-4.712) were identified in APOE epsilon4 carrier subgroup, suggesting that MTHFR 677 T allele and APOE epsilon4 allele may synergistically act to increase AD risk. No significant effect of RFC1 G80A and MTHFR C677T polymorphisms on plasma folate and homocysteine levels was detected.     

Investigation of association of 13 polymorphisms in eight genes in southeastern African American Alzheimer disease patients as compared to age-matched controls

Alzheimer disease (AD) is an emotionally devastating and exceptionally costly disease. Apolipoprotein E (APOE) is a major risk factor gene for AD regardless of age of onset or family history. However, this association may not be as strong or consistent in ethnic groups such as African Americans, raising the possibility of other modifier gene(s). In a group of African American AD patients, a significantly increased risk of AD was associated with two E4 alleles (OR = 5.6; 95% CI = 1.5-21.0) or one E4 allele (OR = 2.5; 95% CI = 1.3-5.0) when compared to E3/E3 genotype, and there was a significant lowering of age of onset for affecteds with E4/E4 genotype as compared to one E2 allele (P = 0.02) or all others (P = 0.03). We also found a significant increase in age of onset with the -308 #2 (A) allele of TNF when compared to AD cases with no #2 allele. A significant increase in age was also demonstrated with the #2 allele (99 base pairs) of the microsatellite TNFa, located approximately 10.5 kb upstream of TNF. When these two alleles were combined with the TNF -238G (#1) allele to give a haplotype, the significant increase in age was still demonstrated. Polymorphisms in the APOE promoter and six other candidate genes did not appear to demonstrate any significant association with our African American AD patients. Our results confirm the established association of APOE4 to AD observed in several ethnic groups, including African Americans. In addition, TNF appears to have some modifying effect in AD, primarily on age of onset, or it could be in linkage disequilibrium with a modifier locus nearby.     

Risk of Alzheimer's disease is associated with a very low-density lipoprotein receptor genotype in Northern Ireland

The epsilon-4 allele of apolipoprotein E (APOE) is associated with increased risk of Alzheimer's disease (AD), but the pathogenic mechanism is unknown. The 5-repeat allele of a CGG repeat polymorphism in the 5' untranslated region of the very low-density lipoprotein receptor (VLDL-R) gene, a receptor for apoE, has been found to be associated with increased risk of AD in a Japanese population. Other groups have been unable to replicate this in American Caucasian populations. A case-control study utilizing a clinically well-defined group of late-onset AD patients (n = 108) and age- and sex-matched control subjects (n = 108) from Northern Ireland was performed to test this association in a relatively homogeneous population. The 9,9 genotype of the VLDL-R was found to be significantly increased in patients compared to controls (P = 0.003; Pcorr = 0.035), leading to an increased risk of AD to subjects with this genotype (OR = 3.9; 95% CI, 1.52-11.25). In contrast to results from the Japanese study, the 5-repeat allele was found to be significantly reduced in the patient group when compared to controls (P = 0.008; Pcorr = 0.047). The results from this study suggest that individuals who have the 9,9 genotype of the VLDL-R gene are at increased risk of AD in Northern Ireland.     

Estrogen receptor beta gene variants are associated with increased risk of Alzheimer's disease in women

We investigated the association of five intronic single-nucleotide polymorphism (SNP) at the estrogen receptor beta (ESR2) gene locus and the susceptibility of developing Alzheimer's disease (AD) in 387 subjects with clinically diagnosed probable AD and 467 cognitively normal individuals derived from eastern Finland. According to our results, variation in the ESR2 gene is associated with an increased risk of AD in women, whereas it does not contribute to the disease susceptibility in men. More specifically, in women, the allele T and the genotype T/T of two of the studied ESR2 gene SNPs (SNP2 and SNP3) were more frequent in AD women than in cognitively normal control women (P=0.012 and P=0.016, respectively). The ESR2 SNP2 T/T genotype and the SNP3 T/T genotype were associated with a significant, nearly two-fold increase in the risk of AD in women (OR=1.87, 95% CI=1.21-2.90), and remained significant after adjustment with the APOE genotype and age (OR=1.63, 95% CI, 1.00-1.68). The combined effect of the ESR2 SNP2 T/T or SNP3 T/T genotype and female gender increases the risk of the disease (OR=3.2, 95% CI=1.3-7.7). Consistent with these results, also the frequency of the haplotype containing the two above ESR2 gene risk alleles was elevated in AD women (P=0.027, OR=1.3, 95% CI=1.02-1.65). Results show that variation in ESR2 gene may be linked with increased AD susceptibility and furthermore, this association is gender specific.     

No association of ERCC1 C8092A and T19007C polymorphisms to cancer risk: a meta-analysis

ERCC1 (excision repair cross complementation group 1) is a subunit of the nucleotide excision repair complex, which can perform DNA strand incision correction of DNA damage. Association studies on the ERCC1 polymorphisms (C8092A and T19007C) in cancer had shown conflicting results. We performed a meta-analysis from all eligible case-control studies to assess the purported associations. Overall, the 19007C allele (3 853 patients and 4 349 controls) showed no significant effect on cancer risk compared to 19007T allele (P=0.39, odds ratio (OR)=0.95; 95% confidence interval (CI) 0.85-1.06, P(heterogeneity)=0.001) in all subjects. Meta-analysis under other genetic contrasts did not reveal any significant association of T19007C to cancer in all subjects, Caucasians and Asians. The 19007C allele (2 279 patients and 2 808 controls) showed no significant effect on lung cancer risk compared to 19007T allele (P=0.72, OR=0.94, 95% CI 0.69-1.29, P(heterogeneity)=0.0001) in all subjects. No significant effect of 8092A allele (3 865 patients and 3 750 controls) on cancer risk in all subjects (P=0.85, OR=1.01, 95% CI 0.94-1.08, P(heterogeneity)=0.92) and in Caucasians and Asians compare to 8092C. No evidences of association of C8092A (501 patients and 620 controls) to squamous cell carcinoma were found. The accumulated evidence indicated ERCC1 T19007C and C8092A might not be risk factors for cancer. Significant between-study heterogeneity existed in T19007C, which arose from a study showing significant protecting effect of 19007C allele compare to 19007T allele in smokers. More studies based on larger, stratified case-control population should be required to further evaluate the role of ERCC1 C8092A and T19007C polymorphisms in different cancer, especially in smokers.     

Gender-specific association of the PTPN22 C1858T polymorphism with achalasia

The protein tyrosine phosphatase N22 (PTPN22) gene encodes a lymphoid-specific phosphatase (LYP), a downregulator of T-cell activation. Because a functional PTPN22 polymorphism, C1858T, has been found to be associated with different autoimmune diseases, we aimed to elucidate the role of this variant in predisposition to achalasia. We performed a case-control study with 231 nonrelated Spanish patients of white ethnicity diagnosed with achalasia and in 554 healthy control subjects, all genotyped for PTPN22 C1858T using TaqMan chemistry. The frequency of the 1858T allele was higher in the achalasia patients than in the healthy controls (carriers of allele T vs CC: OR = 1.38, 95% confidence interval [95% CI] 0.88-2.16, p = 0.13). Moreover a different genotype distribution was found between female and male patients (carriers of allele T vs CC: OR = 2.06, 95% CI 0.96-4.42, p = 0.04) and also between female patients and controls (OR = 1.94, 95% CI 1.12-3.36, p = 0.01), but not between male patients and controls (OR = 0.94, 95% CI 0.50-1.77, p = 0.85). We conclude that the PTPN22 1858T allele is a susceptibility factor for Spanish women with achalasia.     

Lack of interaction between LRP1 and A2M polymorphisms for the risk of Alzheimer disease

Alzheimer disease (AD) has a heterogeneous aetiology, involving genetic and environmental factors. Low-density lipoprotein receptor-related protein 1 (LRP1), alpha-2-macroglobulin (A2M) and apolipoprotein E (APOE) are involved in molecular pathways leading to beta-amyloid deposition. Three polymorphic sites in these genes (APOE-?2/?3/?4, A2M-Ile/Val and LRP1-C/T) have been associated with AD, but the results were not univocal. We carried out a case-control study to investigate the association between these polymorphisms and the risk of developing AD and their possible interaction. We recruited 125 AD patients who fulfilled the diagnostic criteria proposed by NINCDS-ADRDA for probable or possible AD and 310 controls subjects. PCR was used to detect the polymorphisms. ORs and 95% CIs were estimated using logistic regression analysis. The OR for subjects carrying at least one allele Val (A2M-Val+) in their genotypes was 1.52 (95% CI 1.00–2.31; p = 0.05); for subjects carrying at least one allele C (LRP1-C+), 1.58 (95% CI 1.00–2.50; p = 0.05); for subjects carrying at least one allele ?4 (APOE-?4+), 3.1 (95%CI 1.87–5.00; p < 0.001). The coexistence of at least one allele Val (A2M-Val+) and one allele C (LRP1-C+) increased up two times the risk of AD (OR 2.32; 95% CI 1.23–4.35; p < 0.009). No evidence of significant interaction has been found between the studied polymorphisms (p > 0.05). In conclusion our study suggests that LRP1-C/T, A2M-Ile/Val and APOE-?2/?3/?4 polymorphisms are associated with AD.     

TNF polymorphisms in Alzheimer disease and functional implications on CSF beta-amyloid levels

Alzheimer disease (AD), vascular dementia, and stroke are all associated with inflammation though their respective initiating factors differ. Recently a polymorphism in the proinflammatory cytokine tumor necrosis factor (TNF), in association with apolipoprotein E (APOE), was reported to increase AD risk. Two SNPs, rs1799724 (-850C>T; NT_007592.14:g.22400733C>T) and rs1800629 (-308G>A; [NT_007592.14:g.22401282G>A]), and the APOE polymorphism were genotyped in 506 patients with sporadic AD and in 277 cognitively healthy controls. In a subset of 90 individuals we also investigated whether these SNPs exerted any functional effects on cerebrospinal fluid (CSF) beta-amyloid (Abeta) levels. The frequency of the rs1799724 genotypes and the rs1799724-T allele were significantly different in AD individuals (P=0.009; odds ratio [OR], 1.63; 95% confidence interval [CI], 1.13-2.34), while the rs1800629 SNP was not associated with AD. Significant interaction was observed between the rs1799724-T and APOE epsilon4 alleles in that the rs1799724-T allele significantly modified risk associated with possession of the epsilon4 allele only (epsilon4 in absence of rs1799724-T: OR, 2.92; 95% CI, 2.00-4.27; epsilon4 in presence of rs1799724-T: OR, 6.65; 95% CI, 3.26-13.55; P=0.03). Haplotyping analysis revealed a significant overrepresentation of an rs1799724-T/rs1800629-G haplotype in AD (P=0.012; OR, 1.60; 95% CI, 1.11-2.29), although to a lesser degree than rs1799724-T alone. Further, the rs1799724-T allele was found to be associated with lower levels of CSF Abeta42 (P=0.023), thus corroborating the genetic findings. Inheritance of the rs1799724-T allele appears to synergistically increase the risk of AD in APOEepsilon4 carriers and is associated with altered CSF Abeta42 levels. Further investigations are warranted to assess the significance of these novel findings.     

Lack of an association between Paraoxonase 1 gene polymorphisms (Q192R, L55M) and Alzheimer's disease: a meta-analysis

The association between Paraoxonase 1 (PON1) gene polymorphisms (Q192R, L55M) and Alzheimer's disease (AD) risk has been reported inconsistent results. To assess the association between PON1 polymorphisms and AD risk, a meta-analysis was performed. Based on comprehensive searches of the PubMed, Embase, Web of Science, Weipu, and CBM databases, a total of 10 studies including 3081 AD cases and 3054 controls were identified. The pooled odds ratio (OR) with 95% confidence interval (95% CI) were performed. There was no significant association between PON1 Q192R polymorphism and AD risk in all comparison models (R vs. Q, OR=0.89, 95% CI=0.82-0.96; RR vs. QQ, OR=0.83, 95% CI=0.68-1.01; RR+RQ vs. QQ, OR=0.86, 95% CI=0.75-0.97; and RR vs. QR+QQ, OR=0.94, 95% CI=0.81-1.11). For the PON1 L55M polymorphism, lack of an association was also found (L vs. M, OR=0.95, 95% CI=0.86-1.05; LL vs. MM, OR=0.67, 95% CI=0.51-0.88; LL vs. ML+MM, OR=0.82, 95% CI=0.69-0.98; and LL+ML vs. MM, OR=0.75, 95% CI=0.58-0.96). On subgroup analysis by ethnicity, similar results were found. Conclusively, the present meta-analysis revealed that PON1 gene polymorphisms (Q192R, L55M) were unlikely to contribute to AD susceptibility.     

The relationship between tumour necrosis factor-α gene polymorphism and susceptibility and clearance of the persistent hepatitis B virus infection in a Chinese population: a meta-analysis

To date, many studies conducted in the Chinese population have determined the correlation between the tumour necrosis factor-α (TNF-α)-238G/A, -308G/A, -857C/T and -863C/A polymorphisms and persistent hepatitis B virus (HBV) infection. However, their results remain inconclusive. With the aim of confirming this correlation, we performed a meta-analysis of 19 studies. The dichotomous data are presented as the OR with a 95% CI. The results of our study indicate that carriers of the TNF-a-857T allele among the pooled Chinese population were more likely to show spontaneous clearance of HBV (T vs C: OR = 0.824, 95% CI = 0.713–0.953, p 0.009; TT vs CC: OR = 0.701, 95% CI = 0.507–0.970, p 0.032; TC vs CC: OR = 0.804, 95% CI = 0.683–0.947, p 0.009; TT + TC vs CC: OR = 0.835, 95% CI = 0.716–0.974, p 0.021). The TNF-a-308A allele was associated with significantly reduced persistent HBV infection risk in the Chinese (A vs G: OR = 0.585, 95% CI = 0.456–0.751, p 0.002; AG vs GG: OR = 0.519, 95% CI = 0.341–0.789, p <0.000; AA + AG vs GG: OR = 0.512, 95% CI = 0.339–0.772, p 0.001). Persistent HBV infection susceptibility is associated with the TNF-α-308G/A gene polymorphism in the Chinese population, whereas HBV clearance is associated with the TNF-α-857C/T gene polymorphism.