Browsing by Author "Vardarajan, Badri"

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    Genetic variants and functional pathways associated with resilience to Alzheimer’s disease
    (Oxford, 2020-08-25) Dumitrescu, Logan; Mahoney, Emily R; Mukherjee, Shubhabrata; Lee, Michael L; Bush, William S; Engelman, Corinne D; Lu, Qiongshi; Fardo, David W; Trittschuh, Emily H; Mez, Jesse; Kaczorowski, Catherine; Hernandez Saucedo, Hector; Widaman, Keith F; Buckley, Rachel; Properzi, Michael; Mormino, Elizabeth; Yang, Hyun-Sik; Harrison, Tessa; Hedden, Trey; Nho, Kwangsik; Andrews, Shea J; Tommet, Doug; Hadad, Niran; Sanders, R Elizabeth; Ruderfer, Douglas M; Gifford, Katherine A; Moore, Annah M; Cambronero, Francis; Zhong, Xiaoyuan; Raghavan, Neha S.; Vardarajan, Badri; Pericak-Vance, Margaret A.; Farrer, Lindsay A.; Wang, Li-San; Cruchaga, Carlos; Schellenberg, Gerard; Cox, Nancy J.; Haines, Jonathan L,; Keene, C. Dirk; Saykin, Andrew J.; Larson, Eric B.; Sperling, Reisa A.; Mayeux, Richard; Bennett, David A.; Schneider, Julie A.; Crane, Paul K.; Jefferson, Angela L.; Hohman, Timothy J.; Radiology and Imaging Sciences, School of Medicine
    Approximately 30% of older adults exhibit the neuropathological features of Alzheimer’s disease without signs of cognitive impairment. Yet, little is known about the genetic factors that allow these potentially resilient individuals to remain cognitively unimpaired in the face of substantial neuropathology. We performed a large, genome-wide association study (GWAS) of two previously validated metrics of cognitive resilience quantified using a latent variable modelling approach and representing better-than-predicted cognitive performance for a given level of neuropathology. Data were harmonized across 5108 participants from a clinical trial of Alzheimer’s disease and three longitudinal cohort studies of cognitive ageing. All analyses were run across all participants and repeated restricting the sample to individuals with unimpaired cognition to identify variants at the earliest stages of disease. As expected, all resilience metrics were genetically correlated with cognitive performance and education attainment traits (P-values < 2.5 × 10−20), and we observed novel correlations with neuropsychiatric conditions (P-values < 7.9 × 10−4). Notably, neither resilience metric was genetically correlated with clinical Alzheimer’s disease (P-values > 0.42) nor associated with APOE (P-values > 0.13). In single variant analyses, we observed a genome-wide significant locus among participants with unimpaired cognition on chromosome 18 upstream of ATP8B1 (index single nucleotide polymorphism rs2571244, minor allele frequency = 0.08, P = 2.3 × 10−8). The top variant at this locus (rs2571244) was significantly associated with methylation in prefrontal cortex tissue at multiple CpG sites, including one just upstream of ATPB81 (cg19596477; P = 2 × 10−13). Overall, this comprehensive genetic analysis of resilience implicates a putative role of vascular risk, metabolism, and mental health in protection from the cognitive consequences of neuropathology, while also providing evidence for a novel resilience gene along the bile acid metabolism pathway. Furthermore, the genetic architecture of resilience appears to be distinct from that of clinical Alzheimer’s disease, suggesting that a shift in focus to molecular contributors to resilience may identify novel pathways for therapeutic targets.
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    Genome-wide linkage analyses of non-Hispanic white families identify novel loci for familial late-onset Alzheimer's disease
    (Elsevier, 2016-01) Kunkle, Brian W.; Jaworski, James; Barral, Sandra; Vardarajan, Badri; Beecham, Gary W.; Martin, Eden R.; Cantwell, Laura S.; Partch, Amanda; Bird, Thomas D.; Raskind, Wendy H.; DeStefano, Anita L.; Carney, Regina M.; Cuccaro, Michael; Vance, Jeffrey M.; Farrer, Lindsay A.; Goate, Alison M.; Foroud, Tatiana; Mayeux, Richard P.; Schellenberg, Gerard D.; Haines, Jonathan L.; Pericak-Vance, Margaret A.; Department of Medical and Molecular Genetics, IU School of Medicine
    INTRODUCTION: Few high penetrance variants that explain risk in late-onset Alzheimer's disease (LOAD) families have been found. METHODS: We performed genome-wide linkage and identity-by-descent (IBD) analyses on 41 non-Hispanic white families exhibiting likely dominant inheritance of LOAD, and having no mutations at known familial Alzheimer's disease (AD) loci, and a low burden of APOE ε4 alleles. RESULTS: Two-point parametric linkage analysis identified 14 significantly linked regions, including three novel linkage regions for LOAD (5q32, 11q12.2-11q14.1, and 14q13.3), one of which replicates a genome-wide association LOAD locus, the MS4A6A-MS4A4E gene cluster at 11q12.2. Five of the 14 regions (3q25.31, 4q34.1, 8q22.3, 11q12.2-14.1, and 19q13.41) are supported by strong multipoint results (logarithm of odds [LOD*] ≥1.5). Nonparametric multipoint analyses produced an additional significant locus at 14q32.2 (LOD* = 4.18). The 1-LOD confidence interval for this region contains one gene, C14orf177, and the microRNA Mir_320, whereas IBD analyses implicates an additional gene BCL11B, a regulator of brain-derived neurotrophic signaling, a pathway associated with pathogenesis of several neurodegenerative diseases. DISCUSSION: Examination of these regions after whole-genome sequencing may identify highly penetrant variants for familial LOAD.
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    Gliovascular transcriptional perturbations in Alzheimer's disease reveal molecular mechanisms of blood brain barrier dysfunction
    (Springer Nature, 2024-06-20) İş, Özkan; Wang, Xue; Reddy, Joseph S.; Min, Yuhao; Yilmaz, Elanur; Bhattarai, Prabesh; Patel, Tulsi; Bergman, Jeremiah; Quicksall, Zachary; Heckman, Michael G.; Tutor-New, Frederick Q.; Demirdogen, Birsen Can; White, Launia; Koga, Shunsuke; Krause, Vincent; Inoue, Yasuteru; Kanekiyo, Takahisa; Cosacak, Mehmet Ilyas; Nelson, Nastasia; Lee, Annie J.; Vardarajan, Badri; Mayeux, Richard; Kouri, Naomi; Deniz, Kaancan; Carnwath, Troy; Oatman, Stephanie R.; Lewis-Tuffin, Laura J.; Nguyen, Thuy; Alzheimer’s Disease Neuroimaging Initiative; Carrasquillo, Minerva M.; Graff-Radford, Jonathan; Petersen, Ronald C.; Jack, Clifford R., Jr.; Kantarci, Kejal; Murray, Melissa E.; Nho, Kwangsik; Saykin, Andrew J.; Dickson, Dennis W.; Kizil, Caghan; Allen, Mariet; Ertekin-Taner, Nilüfer; Radiology and Imaging Sciences, School of Medicine
    To uncover molecular changes underlying blood-brain-barrier dysfunction in Alzheimer’s disease, we performed single nucleus RNA sequencing in 24 Alzheimer’s disease and control brains and focused on vascular and astrocyte clusters as main cell types of blood-brain-barrier gliovascular-unit. The majority of the vascular transcriptional changes were in pericytes. Of the vascular molecular targets predicted to interact with astrocytic ligands, SMAD3, upregulated in Alzheimer’s disease pericytes, has the highest number of ligands including VEGFA, downregulated in Alzheimer’s disease astrocytes. We validated these findings with external datasets comprising 4,730 pericyte and 150,664 astrocyte nuclei. Blood SMAD3 levels are associated with Alzheimer’s disease-related neuroimaging outcomes. We determined inverse relationships between pericytic SMAD3 and astrocytic VEGFA in human iPSC and zebrafish models. Here, we detect vast transcriptome changes in Alzheimer’s disease at the gliovascular-unit, prioritize perturbed pericytic SMAD3-astrocytic VEGFA interactions, and validate these in cross-species models to provide a molecular mechanism of blood-brain-barrier disintegrity in Alzheimer’s disease.
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    Linkage analyses in Caribbean Hispanic families identify novel loci associated with familial late-onset Alzheimer's disease
    (Elsevier, 2015-12) Barral, Sandra; Cheng, Rong; Reitz, Christiane; Vardarajan, Badri; Lee, Joseph; Kunkle, Brian; Beecham, Gary; Cantwell, Laura S.; Pericak-Vance, Margaret A.; Farrer, Lindsay A.; Haines, Jonathan L.; Goate, Alison M.; Foroud, Tatiana; Boerwinkle, Eric; Schellenberg, Gerard D.; Mayeux, Richard; Department of Medical and Molecular Genetics, IU School of Medicine
    INTRODUCTION: We performed linkage analyses in Caribbean Hispanic families with multiple late-onset Alzheimer's disease (LOAD) cases to identify regions that may contain disease causative variants. METHODS: We selected 67 LOAD families to perform genome-wide linkage scan. Analysis of the linked regions was repeated using the entire sample of 282 families. Validated chromosomal regions were analyzed using joint linkage and association. RESULTS: We identified 26 regions linked to LOAD (HLOD ≥3.6). We validated 13 of the regions (HLOD ≥2.5) using the entire family sample. The strongest signal was at 11q12.3 (rs2232932: HLODmax = 4.7, Pjoint = 6.6 × 10(-6)), a locus located ∼2 Mb upstream of the membrane-spanning 4A gene cluster. We additionally identified a locus at 7p14.3 (rs10255835: HLODmax = 4.9, Pjoint = 1.2 × 10(-5)), a region harboring genes associated with the nervous system (GARS, GHRHR, and NEUROD6). DISCUSSION: Future sequencing efforts should focus on these regions because they may harbor familial LOAD causative mutations.
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    The National Institute on Aging Late-Onset Alzheimer’s Disease Family Based Study: A resource for genetic discovery
    (Wiley, 2022) Reyes-Dumeyer, Dolly; Faber, Kelley; Vardarajan, Badri; Goate, Alison; Renton, Alan; Chao, Michael; Boeve, Brad; Cruchaga, Carlos; Pericak-Vance, Margaret; Haines, Jonathan L.; Rosenberg, Roger; Tsuang, Debby; Sweet, Robert A.; Bennett, David A.; Wilson, Robert S.; Foroud, Tatiana; Mayeux, Richard; Medical and Molecular Genetics, School of Medicine
    Introduction: The National Institute on Aging Late-Onset Alzheimer's Disease Family Based Study (NIA-LOAD FBS) was established to study the genetic etiology of Alzheimer's disease (AD). Methods: Recruitment focused on families with two living affected siblings and a third first-degree relative similar in age with or without dementia. Uniform assessments were completed, DNA was obtained, as was neuropathology, when possible. Apolipoprotein E (APOE) genotypes, genome-wide single nucleotide polymorphism (SNP) arrays, and sequencing was completed in most families. Results: APOE genotype modified the age-at-onset in many large families. Novel variants and known variants associated with early- and late-onset AD and frontotemporal dementia were identified supporting an international effort to solve AD genetics. Discussion: The NIA-LOAD FBS is the largest collection of familial AD worldwide, and data or samples have been included in 123 publications addressing the genetic etiology of AD. Genetic heterogeneity and variability in the age-at-onset provides opportunities to investigate the complexity of familial AD.