Genetic Variants and Related Biomarkers in Sporadic Alzheimer's Disease.
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ABSTRACT:
SUBMITTER: Guerreiro R
PROVIDER: S-EPMC4317514 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BACKGROUND:The complement component (3b/4b) receptor 1 gene (CR1) gene has been proved to affect the susceptibility of Alzheimer's disease (AD) in different ethnic and districts groups. However, the effect of CR1 genetic variants on amyloid ? (A?) metabolism of AD human is still unclear. Hence, the aim of this study was to investigate genetic influences of CR1 gene on A? metabolism. METHODS:All data of AD patients and normal controls (NC) were obtained from alzheimer's disease neuroimaging initiative database (ADNI) database. In order to assess the effect of each single nucleotide polymorphism (SNP) of CR1 on A? metabolism, the PLINK software was used to conduct the quality control procedures to enroll appropriate SNPs. Moreover, the correlation between CR1 genotypes and A? metabolism in all participants were estimated with multiple linear regression models. RESULTS:After quality control procedures, a total of 329 samples and 83 SNPs were enrolled in our study. Moreover, our results identified five SNPs (rs10494884, rs11118322, rs1323721, rs17259045 and rs41308433), which were linked to A? accumulation in brain. In further analyses, rs17259045 was found to decrease A? accumulation among AD patients. Additionally, our study revealed the genetic variants in rs12567945 could increase CSF A?42 in NC population. CONCLUSIONS:Our study had revealed several novel SNPs in CR1 genes which might be involved in the progression of AD via regulating A? accumulation. These findings will provide a new basis for the diagnosis and treatment AD.
| S-EPMC7488421 | biostudies-literature
Project description:Cerebrospinal fluid (CSF) levels of amyloid-β 42 (Aβ42) and tau have been evaluated as endophenotypes in Alzheimer's disease (AD) genetic studies. Although there are sex differences in AD risk, sex differences have not been evaluated in genetic studies of AD endophenotypes. We performed sex-stratified and sex interaction genetic analyses of CSF biomarkers to identify sex-specific associations. Data came from a previous genome-wide association study (GWAS) of CSF Aβ42 and tau (1527 males, 1509 females). We evaluated sex interactions at previous loci, performed sex-stratified GWAS to identify sex-specific associations, and evaluated sex interactions at sex-specific GWAS loci. We then evaluated sex-specific associations between prefrontal cortex (PFC) gene expression at relevant loci and autopsy measures of plaques and tangles using data from the Religious Orders Study and Rush Memory and Aging Project. In Aβ42, we observed sex interactions at one previous and one novel locus: rs316341 within SERPINB1 (p = 0.04) and rs13115400 near LINC00290 (p = 0.002). These loci showed stronger associations among females (β = - 0.03, p = 4.25 × 10-8; β = 0.03, p = 3.97 × 10-8) than males (β = - 0.02, p = 0.009; β = 0.01, p = 0.20). Higher levels of expression of SERPINB1, SERPINB6, and SERPINB9 in PFC was associated with higher levels of amyloidosis among females (corrected p values < 0.02) but not males (p > 0.38). In total tau, we observed a sex interaction at a previous locus, rs1393060 proximal to GMNC (p = 0.004), driven by a stronger association among females (β = 0.05, p = 4.57 × 10-10) compared to males (β = 0.02, p = 0.03). There was also a sex-specific association between rs1393060 and tangle density at autopsy (pfemale = 0.047; pmale = 0.96), and higher levels of expression of two genes within this locus were associated with lower tangle density among females (OSTN p = 0.006; CLDN16 p = 0.002) but not males (p ≥ 0.32). Results suggest a female-specific role for SERPINB1 in amyloidosis and for OSTN and CLDN16 in tau pathology. Sex-specific genetic analyses may improve understanding of AD's genetic architecture.
| S-EPMC6280657 | biostudies-literature
Project description:BACKGROUND:Down syndrome (DS), caused by chromosome 21 trisomy, is associated with an ultra-high risk of dementia due to Alzheimer's disease (AD), driven by amyloid precursor protein (APP) gene triplication. Understanding relevant molecular differences between those with DS, those with sporadic AD (sAD) without DS, and controls will aid in understanding AD development in DS. We explored group differences in plasma concentrations of amyloid-? peptides and tau (as their accumulation is a characteristic feature of AD) and cytokines (as the inflammatory response has been implicated in AD development, and immune dysfunction is common in DS). METHODS:We used ultrasensitive assays to compare plasma concentrations of the amyloid-? peptides A?40 and A?42, total tau (t-tau), and the cytokines IL1?, IL10, IL6, and TNF? between adults with DS (n =?31), adults with sAD (n =?27), and controls age-matched to the group with DS (n =?27), and explored relationships between molecular concentrations and with age within each group. In the group with DS, we also explored relationships with neurofilament light (NfL) concentration, due to its potential use as a biomarker for AD in DS. RESULTS:A?40, A?42, and IL1? concentrations were higher in DS, with a higher A?42/A?40 ratio in controls. The group with DS showed moderate positive associations between concentrations of t-tau and both A?42 and IL1?. Only NfL concentration in the group with DS showed a significant positive association with age. CONCLUSIONS:Concentrations of A?40 and A?42 were much higher in adults with DS than in other groups, reflecting APP gene triplication, while no difference in the A?42/A?40 ratio between those with DS and sAD may indicate similar processing and deposition of A?40 and A?42 in these groups. Higher concentrations of IL1? in DS may reflect an increased vulnerability to infections and/or an increased prevalence of autoimmune disorders, while the positive association between IL1? and t-tau in DS may indicate IL1? is associated with neurodegeneration. Finally, NfL concentration may be the most suitable biomarker for dementia progression in DS. The identification of such a biomarker is important to improve the detection of dementia and monitor its progression, and for designing clinical intervention studies.
| S-EPMC6429702 | biostudies-literature
Project description:IntroductionA minority of patients with sporadic early-onset Alzheimer's disease (AD) exhibit de novo germ line mutations in the autosomal dominant genes such as APP, PSEN1, or PSEN2. We hypothesized that negatively screened patients may harbor somatic variants in these genes.MethodsWe applied an ultrasensitive approach based on single-molecule molecular inversion probes followed by deep next generation sequencing of 11 genes to 100 brain and 355 blood samples from 445 sporadic patients with AD (>80% exhibited an early onset, <66 years).ResultsWe identified and confirmed nine somatic variants (allele fractions: 0.2%-10.8%): two APP, five SORL1, one NCSTN, and one MARK4 variants by independent amplicon-based deep sequencing.DiscussionTwo of the SORL1 variant might have contributed to the disease, the two APP variants were interpreted as likely benign and the other variants remained of unknown significance. Somatic variants in the autosomal dominant AD genes may not be a common cause of sporadic AD, including early onset cases.
| S-EPMC6544509 | biostudies-literature
Project description:We aimed to identify new candidate genes potentially involved in early-onset Alzheimer's disease (EOAD). Exome sequencing was conducted on 45 EOAD patients with either a family history of Alzheimer's disease (AD, <65 years) or an extremely early age at the onset (≤55 years) followed by multiple variant filtering according to different modes of inheritance. We identified 29 candidate genes potentially involved in EOAD, of which the gene TYROBP, previously implicated in AD, was selected for genetic and functional follow-up. Using 3 patient cohorts, we observed rare coding TYROBP variants in 9 out of 1110 EOAD patients, whereas no such variants were detected in 1826 controls (p = 0.0001), suggesting that at least some rare TYROBP variants might contribute to EOAD risk. Overexpression of the p.D50_L51ins14 TYROBP mutant led to a profound reduction of TREM2 expression, a well-established risk factor for AD. This is the first study supporting a role for genetic variation in TYROBP in EOAD, with in vitro support for a functional effect of the p.D50_L51ins14 TYROBP mutation on TREM2 expression.
| S-EPMC5159294 | biostudies-literature
Project description:Late-onset Alzheimer's disease (LOAD) is the most common cause of late-onset dementia in western societies. Despite remarkable achievements in human genetics throughout the years, in particular technological advances in gene mapping and in statistical methods that relate genetic variants to disease, to date only a small proportion of the genetic contribution to LOAD can be explained leaving several remaining genetic risk factors to be identified. A possible explanation for the difficulty in gene identification is that LOAD is a multifactorial complex disorder with both genetic and environmental components. Multiple genes with small effects each ("quantitative trait loci"[QTLs]) are likely to contribute to the quantitative traits associated with the disease, such as memory performance, amyloid/tau pathology, or hippocampal atrophy. The motivation for identifying the genetics of LOAD is clear. Not only could it shed light on disease pathogenesis, but it may also provide potential targets for effective treatment, screening, and prevention. Here, we review the usefulness of genetic variation as diagnostic tools and biomarkers in LOAD and discuss the potentials and difficulties researchers face in designing appropriate studies for gene discovery.
| S-EPMC2819087 | biostudies-literature
Project description:In the current study, differentially expressed cells subpopulations in PBMCs and differentially expressed genes in B cells were identified with 4 AD patients and 2 controls by single-cell sequencing analysis. Some correlations were found among the Clinical Dementia Rating (CDR) score of AD patients, the number variation of B cells and the expression changes of marker genes as the disease developed. The indispensable function of B cell in AD progression was further validated using AD mice. Our results obtained proof-of-concept identification of possible pathogenic cell types and molecular biomarkers underlying AD, concealing the feasibility of predicting disease biomarkers in certain special types of cells rather than in the overall blood and an AD diagnostic or early warning kit based on this single-cell RNA sequencing is urgently needed. Here, a single-cell RNA sequencing analysis of PBMCs from 4 AD patients (2 at early stage, 2 at late stage) and 2 normal controls was performed to explore the differential cell subpopulations in PBMCs of AD patients. A significant decrease of B cells in the blood of AD patients was detected and its reduction was closely correlated with the Clinical Dementia Rating (CDR) score of AD patients. Functional experiments were performed in AD mice to verify the role of B cell in AD progression, and the results demonstrated B cell depletion markedly aggravated the cognitive function and augmented the Aβ burden in AD mice. Importantly, 18 genes were found to be specifically up-regulated and 7 genes down-regulated in B cell as the disease proceeded, among which several exhibited close correlation with AD.
2021-03-10 | GSE168522 | GEO
Project description:INTRODUCTION:Developing cross-validated multi-biomarker models for the prediction of the rate of cognitive decline in Alzheimer's disease (AD) is a critical yet unmet clinical challenge. METHODS:We applied support vector regression to AD biomarkers derived from cerebrospinal fluid, structural magnetic resonance imaging (MRI), amyloid-PET and fluorodeoxyglucose positron-emission tomography (FDG-PET) to predict rates of cognitive decline. Prediction models were trained in autosomal-dominant Alzheimer's disease (ADAD, n = 121) and subsequently cross-validated in sporadic prodromal AD (n = 216). The sample size needed to detect treatment effects when using model-based risk enrichment was estimated. RESULTS:A model combining all biomarker modalities and established in ADAD predicted the 4-year rate of decline in global cognition (R2 = 24%) and memory (R2 = 25%) in sporadic AD. Model-based risk-enrichment reduced the sample size required for detecting simulated intervention effects by 50%-75%. DISCUSSION:Our independently validated machine-learning model predicted cognitive decline in sporadic prodromal AD and may substantially reduce sample size needed in clinical trials in AD.
| S-EPMC7222030 | biostudies-literature
Project description: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 (A?1-42 < 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 (A?1-42 > 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 ?4 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.
| S-EPMC3150628 | biostudies-literature
Project description:Parkinson's disease (PD) is one of the most common neurodegenerative disorders. Accumulated evidence confirms that genetic factors play a considerable role in PD pathogenesis. To examine whether point variants or haplotypes are associated with PD development, genotyping of 35 variants in 22 PD-related genes was performed in a well-characterized cohort of 512 Han Chinese PD patients and 512 normal controls. Both Pearson's χ2 test and haplotype analysis were used to evaluate whether variants or their haplotypes were associated with PD in this cohort. The only statistically significant differences in genotypic and allelic frequencies between the patients and the controls were in the DnaJ heat shock protein family (Hsp40) member C10 gene (DNAJC10) variant rs13414223 (P = 0.004 and 0.002, respectively; odds ratio = 0.652, 95% confidence interval: 0.496-0.857). No other variants or haplotypes exhibited any significant differences between these two groups (all corrected P > 0.05). Our findings indicate that the variant rs13414223 in the DNAJC10 gene, a paralog of PD-related genes DNAJC6 and DNAJC13, may play a protective role in PD. This suggests it may be a PD-associated gene.
| S-EPMC5032117 | biostudies-literature