Rare Variants and Transcriptomics in Alzheimer disease.
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ABSTRACT:
SUBMITTER: Humphries C
PROVIDER: S-EPMC4097329 | biostudies-literature | 2014 Jun
REPOSITORIES: biostudies-literature
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Project description:ObjectiveTo study the association between ABCA7 rare coding variants and Alzheimer disease (AD) in a case-control setting.MethodsWe conducted a whole exome analysis among 484 French patients with early-onset AD and 590 ethnically matched controls.ResultsAfter collapsing rare variants (minor allele frequency ≤1%), we detected an enrichment of ABCA7 loss of function (LOF) and predicted damaging missense variants in cases (odds ratio [OR] 3.40, 95% confidence interval [CI] 1.68-7.35, p = 0.0002). Performing a meta-analysis with previously published data, we found that in a combined sample of 1,256 patients and 1,347 controls from France and Belgium, the OR was 2.81 (95% CI 1.89-4.20, p = 3.60 × 10(-7)).ConclusionsThese results confirm that ABCA7 LOF variants are enriched in patients with AD and extend this finding to predicted damaging missense variants.
| S-EPMC4898320 | biostudies-literature
Project description:Global analysis of RNA from 3 rare skin disease patients extracted from queratinocites and 2 healthy controls (analysis done in triplicate)
2019-08-01 | E-MTAB-3513 | biostudies-arrayexpress
Project description:ObjectiveThe aim of this study was to identify variants associated with familial late-onset Alzheimer disease (AD) using whole-genome sequencing.MethodsSeveral families with an autosomal dominant inheritance pattern of AD were analyzed by whole-genome sequencing. Variants were prioritized for rare, likely pathogenic variants in genes already known to be associated with AD and confirmed by Sanger sequencing using standard protocols.ResultsWe identified 2 rare ABCA7 variants (rs143718918 and rs538591288) with varying penetrance in 2 independent German AD families, respectively. The single nucleotide variant (SNV) rs143718918 causes a missense mutation, and the deletion rs538591288 causes a frameshift mutation of ABCA7. Both variants have previously been reported in larger cohorts but with incomplete segregation information. ABCA7 is one of more than 20 AD risk loci that have so far been identified by genome-wide association studies, and both common and rare variants of ABCA7 have previously been described in different populations with higher frequencies in AD cases than in controls and varying penetrance. Furthermore, ABCA7 is known to be involved in several AD-relevant pathways.ConclusionsWe conclude that both SNVs might contribute to the development of AD in the examined family members. Together with previous findings, our data confirm ABCA7 as one of the most relevant AD risk genes.
| S-EPMC5863691 | biostudies-literature
Project description:ObjectivesMore than 30 different rare mutations, including copy number variants (CNVs), in the amyloid precursor protein gene (APP) cause early-onset familial Alzheimer disease (EOFAD), whereas the contribution of common APP variants to disease risk remains controversial. In this study we systematically assessed the role of both rare and common APP DNA variants in Alzheimer disease (AD) families.MethodsFamilies with EOFAD genetically linked to the APP region were screened for missense mutations and locus duplications of APP. Further, using genome-wide DNA microarray data, we examined the APP locus for CNVs in a total of 797 additional early- and late-onset AD pedigrees. Finally, 423 single nucleotide polymorphisms (SNPs) in the APP locus, including 2 promoter polymorphisms previously associated with AD risk, were tested in up to 4,200 individuals from multiplex AD families.ResultsAnalyses of 8 21q21-linked families revealed one family carrying a nonsynonymous mutation in exon 17 (Val717Leu) and another family with a partially penetrant 3.5-Mb locus duplication encompassing APP. CNV analysis in the APP locus revealed an additional family carrying a fully penetrant 380-kb duplication, merely spanning APP. Last, contrary to previous reports, association analyses of more than 400 different SNPs in or near APP failed to show significant effects on AD risk.ConclusionOur study shows that APP mutations and locus duplications are a very rare cause of EOFAD and that the contribution of common APP variants to AD susceptibility is insignificant. Furthermore, duplications of APP may not be fully penetrant, possibly indicating the existence of hitherto unknown protective genetic factors.
| S-EPMC3324321 | biostudies-literature
Project description:ImportanceThe APOE ε2 and APOE ε4 alleles are the strongest protective and risk-increasing, respectively, genetic variants for late-onset Alzheimer disease (AD). However, the mechanisms linking APOE to AD-particularly the apoE protein's role in AD pathogenesis and how this is affected by APOE variants-remain poorly understood. Identifying missense variants in addition to APOE ε2 and APOE ε4 could provide critical new insights, but given the low frequency of additional missense variants, AD genetic cohorts have previously been too small to interrogate this question robustly.ObjectiveTo determine whether rare missense variants on APOE are associated with AD risk.Design, setting, and participantsAssociation with case-control status was tested in a sequenced discovery sample (stage 1) and followed up in several microarray imputed cohorts as well as the UK Biobank whole-exome sequencing resource using a proxy-AD phenotype (stages 2 and 3). This study combined case-control, family-based, population-based, and longitudinal AD-related cohorts that recruited referred and volunteer participants. Stage 1 included 37 409 nonunique participants of European or admixed European ancestry, with 11 868 individuals with AD and 11 934 controls passing analysis inclusion criteria. In stages 2 and 3, 475 473 participants were considered across 8 cohorts, of which 84 513 individuals with AD and proxy-AD and 328 372 controls passed inclusion criteria. Selection criteria were cohort specific, and this study was performed a posteriori on individuals who were genotyped. Among the available genotypes, 76 195 were excluded. All data were retrieved between September 2015 and November 2021 and analyzed between April and November 2021.Main outcomes and measuresIn primary analyses, the AD risk associated with each missense variant was estimated, as appropriate, with either linear mixed-model regression or logistic regression. In secondary analyses, associations were estimated with age at onset using linear mixed-model regression and risk of conversion to AD using competing-risk regression.ResultsA total of 544 384 participants were analyzed in the primary case-control analysis; 312 476 (57.4%) were female, and the mean (SD; range) age was 64.9 (15.2; 40-110) years. Two missense variants were associated with a 2-fold to 3-fold decreased AD risk: APOE ε4 (R251G) (odds ratio, 0.44; 95% CI, 0.33-0.59; P = 4.7 × 10-8) and APOE ε3 (V236E) (odds ratio, 0.37; 95% CI, 0.25-0.56; P = 1.9 × 10-6). Additionally, the cumulative incidence of AD in carriers of these variants was found to grow more slowly with age compared with noncarriers.Conclusions and relevanceIn this genetic association study, a novel variant associated with AD was identified: R251G always coinherited with ε4 on the APOE gene, which mitigates the ε4-associated AD risk. The protective effect of the V236E variant, which is always coinherited with ε3 on the APOE gene, was also confirmed. The location of these variants confirms that the carboxyl-terminal portion of apoE plays an important role in AD pathogenesis. The large risk reductions reported here suggest that protein chemistry and functional assays of these variants should be pursued, as they have the potential to guide drug development targeting APOE.
| S-EPMC9157381 | biostudies-literature
Project description:Rare variants in the phospholipase D3 gene (PLD3) were associated with increased risk for late-onset Alzheimer disease (LOAD). We identified a missense mutation in PLD3 in whole-genome sequence data of a patient with autopsy confirmed Alzheimer disease (AD) and onset age of 50 years. Subsequently, we sequenced PLD3 in a Belgian early-onset Alzheimer disease (EOAD) patient (N = 261) and control (N = 319) cohort, as well as in European EOAD patients (N = 946) and control individuals (N = 1,209) ascertained in different European countries. Overall, we identified 22 rare variants with a minor allele frequency <1%, 20 missense and two splicing mutations. Burden analysis did not provide significant evidence for an enrichment of rare PLD3 variants in EOAD patients in any of the patient/control cohorts. Also, meta-analysis of the PLD3 data, including a published dataset of a German EOAD cohort, was not significant (P = 0.43; OR = 1.53, 95% CI 0.60-3.31). Consequently, our data do not support a role for PLD3 rare variants in the genetic etiology of EOAD in European EOAD patients. Our data corroborate the negative replication data obtained in LOAD studies and therefore a genetic role of PLD3 in AD remains to be demonstrated.
| S-EPMC5057316 | biostudies-literature
Project description:High-throughput sequencing of RNA from olfactory epithelium of mice modeling Alzheimer's disease with olfactory deficits. We sequenced cDNA libararies from the main olfactory epithelium (MOE) of nine mice from 3 strains (C57BL/6, T43 with P201S mutation, 129S5): 3 groups consists of 9 mice. RNA was extracted using a Qiagen RNAeasy kit and standard methods. All nine RNA samples were multiplexed together and sequenced in three lanes on the Illumina HiSeq platform. This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/ or email dl5@sanger.ac.uk
2012-07-02 | E-ERAD-160 | biostudies-arrayexpress
Project description:Alzheimer’s disease (AD) is an age-related neurodegenerative progressive disorder affecting 10% of people over 65. Less than 5% of patients have known causal genetic mutations while the exact cause of AD for the majority of patients, especially the late onset form, is unknown. Large scale epigenomic studies revealed that disease associated SNPs are highly enriched in cell-type-specific cis-regulatory elements. In AD, SNPs are more significantly enriched in the regulatory regions of myeloid lineages rather than the neuronal cells. However, how AD SNPs affect microglia enhancers, and more interestingly differentially affect state-specific enhancers such as activated upon stimulation, e.g. viral infection, remain largely unexplored. In this study we identified cis-regulatory elements in both resting and IFN-beta stimulated microglia and further functionally characterized how regulatory SNPs lead to immune response dysregulation in the pathogenesis of AD.
2023-07-31 | GSE207629 | GEO
Project description:Alzheimer’s disease (AD) is an age-related neurodegenerative progressive disorder affecting 10% of people over 65. Less than 5% of patients have known causal genetic mutations while the exact cause of AD for the majority of patients, especially the late onset form, is unknown. Large scale epigenomic studies revealed that disease associated SNPs are highly enriched in cell-type-specific cis-regulatory elements. In AD, SNPs are more significantly enriched in the regulatory regions of myeloid lineages rather than the neuronal cells. However, how AD SNPs affect microglia enhancers, and more interestingly differentially affect state-specific enhancers such as activated upon stimulation, e.g. viral infection, remain largely unexplored. In this study we identified cis-regulatory elements in both resting and IFN-beta stimulated microglia and further functionally characterized how regulatory SNPs lead to immune response dysregulation in the pathogenesis of AD.
2023-07-31 | GSE207628 | GEO
Project description:Alzheimer’s disease (AD) is an age-related neurodegenerative progressive disorder affecting 10% of people over 65. Less than 5% of patients have known causal genetic mutations while the exact cause of AD for the majority of patients, especially the late onset form, is unknown. Large scale epigenomic studies revealed that disease associated SNPs are highly enriched in cell-type-specific cis-regulatory elements. In AD, SNPs are more significantly enriched in the regulatory regions of myeloid lineages rather than the neuronal cells. However, how AD SNPs affect microglia enhancers, and more interestingly differentially affect state-specific enhancers such as activated upon stimulation, e.g. viral infection, remain largely unexplored. In this study we identified cis-regulatory elements in both resting and IFN-beta stimulated microglia and further functionally characterized how regulatory SNPs lead to immune response dysregulation in the pathogenesis of AD.
2023-07-31 | GSE206480 | GEO