Publications by authors named "Kynon J M Benjamin"

Motivation: Local ancestry inference is a powerful technique in genetics, revealing population history and the genetic basis of diseases. It is particularly valuable for improving eQTL discovery and fine-mapping in admixed populations. Despite the widespread use of the RFMix software for local ancestry inference, large-scale genomic studies face challenges of high memory consumption and processing times when handling RFMix output files.

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Article Synopsis
  • Ancestral differences in genomic variation influence gene expression, with most studies focusing on European samples or adjusting for ancestry, rather than specifically examining it.
  • This study explored how genetic ancestry impacts gene expression and DNA methylation in brain tissue from admixed Black American individuals, revealing ancestry-related genes primarily involved in immune response and vascular tissue rather than neurons.
  • The identified ancestry-associated differentially expressed genes (DEGs) contribute to heritability for various conditions like ischemic stroke, Parkinson's, and Alzheimer's, highlighting significant differences in gene expression based on genetic ancestry and its implications for brain-related illnesses.
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Schizophrenia is a complex neuropsychiatric disorder with sexually dimorphic features, including differential symptomatology, drug responsiveness, and male incidence rate. Prior large-scale transcriptome analyses for sex differences in schizophrenia have focused on the prefrontal cortex. Analyzing BrainSeq Consortium data (caudate nucleus: n = 399, dorsolateral prefrontal cortex: n = 377, and hippocampus: n = 394), we identified 831 unique genes that exhibit sex differences across brain regions, enriched for immune-related pathways.

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Objective: Schizophrenia is a brain disorder that originates during neurodevelopment and has complex genetic and environmental etiologies. Despite decades of clinical evidence of altered striatal function in affected patients, studies examining its cellular and molecular mechanisms in humans are limited. To explore neurodevelopmental alterations in the striatum associated with schizophrenia, the authors established a method for the differentiation of induced pluripotent stem cells (iPSCs) into ventral forebrain organoids (VFOs).

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Motivation: Advances in technology have generated larger omics datasets with potential applications for machine learning. In many datasets, however, cost and limited sample availability result in an excessively higher number of features as compared to observations. Moreover, biological processes are associated with networks of core and peripheral genes, while traditional feature selection approaches capture only core genes.

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Article Synopsis
  • * Ancestry-associated differentially expressed genes (DEGs) are linked to immune response and vascular tissue, contributing to heritability for conditions like ischemic stroke, Parkinson's disease, and Alzheimer's disease, while showing less influence on psychiatric traits.
  • * The study reveals that both genetic variation and environmental factors (like DNA methylation) shape gene expression differences across ancestry, impacting the risk of brain illnesses in diverse populations.
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Most studies of gene expression in the brains of individuals with schizophrenia have focused on cortical regions, but subcortical nuclei such as the striatum are prominently implicated in the disease, and current antipsychotic drugs target the striatum's dense dopaminergic innervation. Here, we performed a comprehensive analysis of the genetic and transcriptional landscape of schizophrenia in the postmortem caudate nucleus of the striatum of 443 individuals (245 neurotypical individuals, 154 individuals with schizophrenia and 44 individuals with bipolar disorder), 210 from African and 233 from European ancestries. Integrating expression quantitative trait loci analysis, Mendelian randomization with the latest schizophrenia genome-wide association study, transcriptome-wide association study and differential expression analysis, we identified many genes associated with schizophrenia risk, including potentially the dopamine D2 receptor short isoform.

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X-linked Dystonia-Parkinsonism (XDP) is an inherited, X-linked, adult-onset movement disorder characterized by degeneration in the neostriatum. No therapeutics alter disease progression. The mechanisms underlying regional differences in degeneration and adult onset are unknown.

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Despite extensive genetic and neuroimaging studies, detailed cellular mechanisms underlying schizophrenia and bipolar disorder remain poorly understood. Recent progress in single-cell RNA sequencing (scRNA-seq) technologies enables identification of cell-type-specific pathophysiology. However, its application to psychiatric disorders is challenging because of methodological difficulties in analyzing human brains and the confounds due to a lifetime of illness.

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Article Synopsis
  • The study created induced pluripotent stem (iPS) cell lines using fibroblasts from the dura mater of four deceased individuals who had low genetic risk for psychiatric disorders like schizophrenia and bipolar disorder.
  • The fibroblasts were reprogrammed into iPS cells using specific genetic factors delivered through episomal vectors.
  • All iPS cell lines maintained the same genetic profile as the original brain tissues, expressed markers indicating pluripotency, and demonstrated the ability to differentiate into all three embryonic germ layers.
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