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    Item type:Publication,
    Comprehensive Analysis of Genetic Contributions to Alzheimer’s Disease and Frontotemporal Dementia in Admixed Latin American Populations
    (Wiley, 2024-12)
    Juliana Acosta‐Uribe
    ;
    Stefanie Danielle Pina Escudero
    ;
    J. Nicholas Cochran
    ;
    Jared W Taylor
    ;
    Caroline Warly Solsberg
    <jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Most research initiatives have emerged from high‐income countries (HIC), leaving a gap in understanding the disease’s genetic basis in diverse populations like those in Latin American countries (LAC). ReDLat tackles this gap, focusing on LAC’s unique genetics and socioeconomic factors to identify specific Alzheimer’s Disease (AD) and Frontotemporal Dementia (FTD) risk factors in Mexico, Colombia, Peru, Chile, Argentina, and Brazil.</jats:p></jats:sec><jats:sec><jats:title>Method</jats:title><jats:p>We employed a comprehensive genetic analysis approach, integrating Whole Genome Sequencing (WGS), Exome Sequencing, and SNP arrays to understand the cohort’s unique genetic architecture. We conducted ancestry analysis and searched for disease‐causing variants with mendelian inheritance, genome‐wide association studies (GWAS), rare variant enrichment, and evaluation of Polygenic Risk Scores (PRS).</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>We recruited and genotyped an initial cohort of 1046 participants with AD, 423 with FTD, and 855 healthy controls (HC) between 2020 and 2023. Analysis is ongoing, and we expect to sequence ∼600 additional samples in the coming months. Ancestry analysis revealed tri‐continental admixture, except for Brazil, which showed an additional Asian component (Figure 1). Top candidate gene rare variant enrichment associations (SKAT p &lt; 0.05) were <jats:italic>TREM2</jats:italic> for FTD and <jats:italic>ABCA7</jats:italic> and <jats:italic>ABCA1</jats:italic> for AD. GWAS identified a robust association with the <jats:italic>APOE</jats:italic> locus on chromosome 19 in AD vs. HC.. We tested an AD PRS developed in European populations by Bellenguez et al (2020). on our cohort using 83 single‐nucleotide polymorphisms.. The PRS modestly distinguishes between all patients and HC (p = 2.4 × 10^‐12), AD vs. HC (p = 2.2 × 10^‐12), and even FTD vs. HC (p = 4.3 × 10^‐5), albeit with modest separation between groups, as expected for its application in a genetically admixed population.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>Our findings represent a pivotal step in understanding the genetic landscape of AD and FTD in admixed populations. They underscore the importance of including diverse populations in genetic research, paving the way for future studies. These findings have the potential to inform more personalized approaches to the diagnosis and treatment of neurodegenerative diseases in diverse global populations, as well as identify novel targets for therapeutic development.</jats:p></jats:sec>
      3
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    Item type:Publication,
    The first genome‐wide association study in the Argentinian and Chilean populations identifies shared genetics with Europeans in Alzheimer's disease
    (2023)
    Maria Carolina Dalmasso
    ;
    Itziar de Rojas
    ;
    Natividad Olivar
    ;
    Carolina Muchnik
    ;
    Bárbara Angel
    <jats:title>Abstract</jats:title><jats:sec><jats:title>INTRODUCTION</jats:title><jats:p>Genome‐wide association studies (GWAS) are fundamental for identifying loci associated with diseases. However, they require replication in other ethnicities.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>We performed GWAS on sporadic Alzheimer's disease (AD) including 539 patients and 854 controls from Argentina and Chile. We combined our results with those from the European Alzheimer and Dementia Biobank (EADB) in a meta‐analysis and tested their genetic risk score (GRS) performance in this admixed population.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>We detected apolipoprotein E ε4 as the single genome‐wide significant signal (odds ratio  = 2.93 [2.37–3.63], <jats:italic>P</jats:italic> = 2.6 × 10<jats:sup>−23</jats:sup>). The meta‐analysis with EADB summary statistics revealed four new loci reaching GWAS significance. Functional annotations of these loci implicated endosome/lysosomal function. Finally, the AD‐GRS presented a similar performance in these populations, despite the score diminished when the Native American ancestry rose.</jats:p></jats:sec><jats:sec><jats:title>DISCUSSION</jats:title><jats:p>We report the first GWAS on AD in a population from South America. It shows shared genetics modulating AD risk between the European and these admixed populations.</jats:p></jats:sec><jats:sec><jats:title>Highlights</jats:title><jats:p><jats:list list-type="bullet"> <jats:list-item><jats:p>This is the first genome‐wide association study on Alzheimer's disease (AD) in a population sample from Argentina and Chile.</jats:p></jats:list-item> <jats:list-item><jats:p>Trans‐ethnic meta‐analysis reveals four new loci involving lysosomal function in AD.</jats:p></jats:list-item> <jats:list-item><jats:p>This is the first independent replication for <jats:italic>TREM2L</jats:italic>, <jats:italic>IGH‐gene‐cluster</jats:italic>, and <jats:italic>ADAM17</jats:italic> loci.</jats:p></jats:list-item> <jats:list-item><jats:p>A genetic risk score (GRS) developed in Europeans performed well in this population.</jats:p></jats:list-item> <jats:list-item><jats:p>The higher the Native American ancestry the lower the GRS values.</jats:p></jats:list-item> </jats:list></jats:p></jats:sec>
    Scopus© Citations 3  1
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    Item type:Publication,
    Genome Sequencing Variations in the Octodon degus, an Unconventional Natural Model of Aging and Alzheimer's Disease
    (2022)
    Michael J. Hurley
    ;
    Claudio Urra
    ;
    B. Maximiliano Garduno
    ;
    Agostino Bruno
    ;
    Allison Kimbell
    <jats:p>The degu (<jats:italic>Octodon degus</jats:italic>) is a diurnal long-lived rodent that can spontaneously develop molecular and behavioral changes that mirror those seen in human aging. With age some degu, but not all individuals, develop cognitive decline and brain pathology like that observed in Alzheimer's disease including neuroinflammation, hyperphosphorylated tau and amyloid plaques, together with other co-morbidities associated with aging such as macular degeneration, cataracts, alterations in circadian rhythm, diabetes and atherosclerosis. Here we report the whole-genome sequencing and analysis of the degu genome, which revealed unique features and molecular adaptations consistent with aging and Alzheimer's disease. We identified single nucleotide polymorphisms in genes associated with Alzheimer's disease including a novel apolipoprotein E (<jats:italic>Apoe</jats:italic>) gene variant that correlated with an increase in amyloid plaques in brain and modified the <jats:italic>in silico</jats:italic> predicted degu APOE protein structure and functionality. The reported genome of an unconventional long-lived animal model of aging and Alzheimer's disease offers the opportunity for understanding molecular pathways involved in aging and should help advance biomedical research into treatments for Alzheimer's disease.</jats:p>
      3Scopus© Citations 12