Publications by authors named "J. Nicholas Cochran"

Article Synopsis
  • Latin America's genetic diversity offers a unique opportunity to study Alzheimer's disease (AD) and frontotemporal dementia (FTD), with a focus on identifying related genetic variations.
  • The study involved 2,162 participants from six countries who underwent extensive genomic sequencing and analysis to detect genetic factors linked to these dementias.
  • Results highlighted a mix of American, African, and European ancestries, discovered 17 pathogenic variants, and revealed specific genetic variations tied to AD and FTD inheritance patterns in affected families.
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Introduction: Variants of uncertain significance (VUS) surged with affordable genetic testing, posing challenges for determining pathogenicity. We examine the pathogenicity of a novel VUS P93S in Annexin A11 (ANXA11) - an amyotrophic lateral sclerosis/frontotemporal dementia-associated gene - in a corticobasal syndrome kindred. Established ANXA11 mutations cause ANXA11 aggregation, altered lysosomal-RNA granule co-trafficking, and transactive response DNA binding protein of 43 kDa (TDP-43) mis-localization.

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Unlabelled: Tau reduction is a promising therapeutic strategy for Alzheimer's disease. In numerous models, tau reduction via genetic knockout is beneficial, at least in part due to protection against hyperexcitability and seizures, but the underlying mechanisms are unclear. Here we describe the generation and initial study of a new conditional Tau model to address these mechanisms.

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Alzheimer's disease (AD) is the leading cause of dementia and lacks highly effective treatments. Tau-based therapies hold promise. Tau reduction prevents amyloid-β-induced dysfunction in preclinical models of AD and also prevents amyloid-β-independent dysfunction in diverse disease models, especially those with network hyperexcitability, suggesting that strategies exploiting the mechanisms underlying Tau reduction may extend beyond AD.

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Tauopathies are a group of neurodegenerative diseases defined by abnormal aggregates of tau, a microtubule-associated protein encoded by MAPT. MAPT expression is near absent in neural progenitor cells (NPCs) and increases during differentiation. This temporally dynamic expression pattern suggests that MAPT expression could be controlled by transcription factors and cis-regulatory elements specific to differentiated cell types.

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As genetic testing has become more accessible and affordable, variants of uncertain significance (VUS) are increasingly identified, and determining whether these variants play causal roles in disease is a major challenge. The known disease-associated Annexin A11 (ANXA11) mutations result in ANXA11 aggregation, alterations in lysosomal-RNA granule co-trafficking, and TDP-43 mis-localization and present as amyotrophic lateral sclerosis or frontotemporal dementia. We identified a novel VUS in ANXA11 (P93S) in a kindred with corticobasal syndrome and unique radiographic features that segregated with disease.

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Article Synopsis
  • * A study applied a polygenic hazard score to early-onset AD patients and found that their scores were similar to those of late-onset patients, suggesting that genetic factors associated with late-onset AD do not explain early-onset cases.
  • * The research indicates that early-onset AD has a distinct genetic makeup compared to late-onset AD, highlighting the need for further investigation into unique genetic factors related to early-onset AD.
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Women have a higher incidence of Alzheimer's disease (AD), even after adjusting for increased longevity. Thus, there is an urgent need to identify the molecular networks that underpin the sex-associated risk of AD. Recent efforts have identified as a key regulator of tau phosphorylation signaling pathway is the only gene, to date, that when deleted can cause both tau and Aβ-related pathologies in an age-dependent manner.

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Objective: GM2 gangliosidosis is usually fatal by 5 years of age in its 2 major subtypes, Tay-Sachs and Sandhoff disease. First reported in 1881, GM2 gangliosidosis has no effective treatment today, and children succumb to the disease after a protracted neurodegenerative course and semi-vegetative state. This study seeks to further develop adeno-associated virus (AAV) gene therapy for human translation.

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Article Synopsis
  • - The study analyzed genomic data from 100 patients with early-onset or atypical dementia, including 68 newly described cases, predominantly composed of white, non-Hispanic individuals.
  • - Among the cohort, 53% had a returnable genetic variant, with 5 patients identified as having pathogenic variants according to established medical criteria.
  • - A comparison of polygenic risk scores revealed that early-onset Alzheimer's patients had higher scores than those with late-onset Alzheimer's, indicating both rare and common genetic factors contribute to the risk of early-onset neurodegenerative diseases.
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Background: Tauopathies are a group of neurodegenerative diseases driven by abnormal aggregates of tau, a microtubule associated protein encoded by the gene. expression is absent in neural progenitor cells (NPCs) and increases during differentiation. This temporally dynamic expression pattern suggests that expression is controlled by transcription factors and cis-regulatory elements specific to differentiated cell types.

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Article Synopsis
  • - The study focuses on a Colombian family with a specific genetic mutation related to early-onset Alzheimer's disease, aiming to find genetic factors that affect the age at which the disease manifests.
  • - Researchers analyzed genetic data from 340 individuals carrying the PSEN1 E280A mutation and found 13 genetic variants linked to Alzheimer's onset, with three significant variants associated with the gene clusterin.
  • - The identified genetic variants are suggested to influence biological processes related to Alzheimer’s, highlighting their possible importance in developing future therapies, especially given the strong existing mutation linked to the disease.
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Cell type-specific transcriptional differences between brain tissues from donors with Alzheimer's disease (AD) and unaffected controls have been well documented, but few studies have rigorously interrogated the regulatory mechanisms responsible for these alterations. We performed single nucleus multiomics (snRNA-seq plus snATAC-seq) on 105,332 nuclei isolated from cortical tissues from 7 AD and 8 unaffected donors to identify candidate -regulatory elements (CREs) involved in AD-associated transcriptional changes. We detected 319,861 significant correlations, or links, between gene expression and cell type-specific transposase accessible regions enriched for active CREs.

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We collected and analyzed genomic sequencing data from individuals with clinician- diagnosed early-onset or atypical dementia. Thirty-two patients were previously described, with sixty-eight newly described in this report. Of those sixty-eight, sixty-two patients reported Caucasian, non-Hispanic ethnicity and six reported as African American, non-Hispanic.

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Alzheimer's disease (AD), the leading cause of dementia, has an estimated heritability of approximately 70%. The genetic component of AD has been mainly assessed using genome-wide association studies, which do not capture the risk contributed by rare variants. Here, we compared the gene-based burden of rare damaging variants in exome sequencing data from 32,558 individuals-16,036 AD cases and 16,522 controls.

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Limited knowledge on dementia biomarkers in Latin American and Caribbean (LAC) countries remains a serious barrier. Here, we reported a survey to explore the ongoing work, needs, interests, potential barriers, and opportunities for future studies related to biomarkers. The results show that neuroimaging is the most used biomarker (73%), followed by genetic studies (40%), peripheral fluids biomarkers (31%), and cerebrospinal fluid biomarkers (29%).

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Article Synopsis
  • The Colombian population shows a unique genetic background due to a mix of Native American, Spanish, and African ancestries, influenced by past population bottlenecks caused by diseases.
  • Through genetic analysis of 900 individuals, including those with Alzheimer's and other neurodegenerative disorders, researchers identified how historical admixture has shaped the occurrence of disease-related mutations.
  • The study found 21 pathogenic variants related to neurodegenerative diseases, with significant variation in risk based on ancestry, highlighting the importance of demographic history in understanding genetic diseases in the Colombian population.
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Dementia is becoming increasingly prevalent in Latin America, contrasting with stable or declining rates in North America and Europe. This scenario places unprecedented clinical, social, and economic burden upon patients, families, and health systems. The challenges prove particularly pressing for conditions with highly specific diagnostic and management demands, such as frontotemporal dementia.

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Dravet syndrome (DS) is a developmental and epileptic encephalopathy that results from mutations in the Nav1.1 sodium channel encoded by SCN1A. Most known DS-causing mutations are in coding regions of SCN1A, but we recently identified several disease-associated SCN1A mutations in intron 20 that are within or near to a cryptic and evolutionarily conserved "poison" exon, 20N, whose inclusion is predicted to lead to transcript degradation.

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Cerebral cortical size and organization are critical features of neurodevelopment and human evolution, for which genetic investigation in model organisms can provide insight into developmental mechanisms and the causes of cerebral malformations. However, some abnormalities in cerebral cortical proliferation and folding are challenging to study in laboratory mice due to the absence of gyri and sulci in rodents. We report an autosomal recessive allele in domestic cats associated with impaired cerebral cortical expansion and folding, giving rise to a smooth, lissencephalic brain, and that appears to be caused by homozygosity for a frameshift in PEA15 (phosphoprotein expressed in astrocytes-15).

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Genome-wide association studies identified the locus as a leading modulator of genetic risk in Alzheimer's disease (AD). One limitation in understanding 's contribution to AD is its unknown function in the brain. AD-associated variants are generally noncoding and likely change expression.

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We conducted genome sequencing to search for rare variation contributing to early-onset Alzheimer's disease (EOAD) and frontotemporal dementia (FTD). Discovery analysis was conducted on 435 cases and 671 controls of European ancestry. Burden testing for rare variation associated with disease was conducted using filters based on variant rarity (less than one in 10,000 or private), computational prediction of deleteriousness (CADD) (10 or 15 thresholds), and molecular function (protein loss-of-function [LoF] only, coding alteration only, or coding plus non-coding variants in experimentally predicted regulatory regions).

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We assessed the results of genome sequencing for early-onset dementia. Participants were selected from a memory disorders clinic. Genome sequencing was performed along with repeat expansion testing.

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