Publications by authors named "Charles Gu"

Background Gene-environment interactions may enhance our understanding of hypertension. Our previous study highlighted the importance of considering psychosocial factors in gene discovery for blood pressure (BP) but was limited in statistical power and population diversity. To address these challenges, we conducted a multi-population genome-wide association study (GWAS) of BP accounting for gene-depressive symptomatology (DEPR) interactions in a larger and more diverse sample.

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Large-scale whole-genome sequencing (WGS) studies have improved our understanding of the contributions of coding and noncoding rare variants to complex human traits. Leveraging association effect sizes across multiple traits in WGS rare variant association analysis can improve statistical power over single-trait analysis, and also detect pleiotropic genes and regions. Existing multi-trait methods have limited ability to perform rare variant analysis of large-scale WGS data.

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Large-scale gene-environment interaction (GxE) discovery efforts often involve analytical compromises for the sake of data harmonization and statistical power. Refinement of exposures, covariates, outcomes, and population subsets may be helpful to establish often-elusive replication and evaluate potential clinical utility. Here, we used additional datasets, an expanded set of statistical models, and interrogation of lipoprotein metabolism via nuclear magnetic resonance (NMR)-based lipoprotein subfractions to refine a previously discovered GxE modifying the relationship between physical activity (PA) and HDL-cholesterol (HDL-C).

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Article Synopsis
  • * We found 17 genetic loci associated with sleep duration impacting lipid levels, with 10 of them being newly identified and linked to sleep-related disturbances in lipid metabolism.
  • * The research points to potential drug targets that could lead to new treatments for lipid-related issues in individuals with sleep problems, highlighting the connection between sleep patterns and cardiovascular health.
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  • Clonal hematopoiesis (CH) occurs when genetically identical blood cells expand, often influenced by genetic mutations linked to blood cancers; however, many cases happen without known driver mutations.
  • Researchers analyzed 51,399 genomes to study a specific type of CH (CH-LPMneg) without detectable leukemia-related mutations, developing a new method (GEM rate) to estimate mutation burden without paired samples.
  • Through their study, they identified seven genes linked to CH-LPMneg and found that alterations in hematopoietic stem cell (HSC) behavior may drive this mutation burden, while a broader analysis revealed relationships between GEM and the expression of 404 genes.
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Although both short and long sleep duration are associated with elevated hypertension risk, our understanding of their interplay with biological pathways governing blood pressure remains limited. To address this, we carried out genome-wide cross-population gene-by-short-sleep and long-sleep duration interaction analyses for three blood pressure traits (systolic, diastolic, and pulse pressure) in 811,405 individuals from diverse population groups. We discover 22 novel gene-sleep duration interaction loci for blood pressure, mapped to 23 genes.

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Clonal hematopoiesis of indeterminate potential (CHIP), whereby somatic mutations in hematopoietic stem cells confer a selective advantage and drive clonal expansion, not only correlates with age but also confers increased risk of morbidity and mortality. Here, we leverage genetically predicted traits to identify factors that determine CHIP clonal expansion rate. We used the passenger-approximated clonal expansion rate method to quantify the clonal expansion rate for 4,370 individuals in the National Heart, Lung, and Blood Institute (NHLBI) Trans-Omics for Precision Medicine (TOPMed) cohort and calculated polygenic risk scores for DNA methylation aging, inflammation-related measures and circulating protein levels.

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We construct non-linear machine learning (ML) prediction models for systolic and diastolic blood pressure (SBP, DBP) using demographic and clinical variables and polygenic risk scores (PRSs). We developed a two-model ensemble, consisting of a baseline model, where prediction is based on demographic and clinical variables only, and a genetic model, where we also include PRSs. We evaluate the use of a linear versus a non-linear model at both the baseline and the genetic model levels and assess the improvement in performance when incorporating multiple PRSs.

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Human induced pluripotent stem cells (hiPSCs) are frequently used to study disease-associated variations. We characterized transcriptional variability from a hiPSC-derived cardiomyocyte (hiPSC-CM) study of left ventricular hypertrophy (LVH) using donor samples from the HyperGEN study. Multiple hiPSC-CM differentiations over reprogramming events (iPSC generation) across 7 donors were used to assess variabilities from reprogramming, differentiation, and donor LVH status.

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Although both short and long sleep duration are associated with elevated hypertension risk, our understanding of their interplay with biological pathways governing blood pressure remains limited. To address this, we carried out genome-wide cross-population gene-by-short-sleep and long-sleep duration interaction analyses for three blood pressure traits (systolic, diastolic, and pulse pressure) in 811,405 individuals from diverse population groups. We discover 22 novel gene-sleep duration interaction loci for blood pressure, mapped to genes involved in neurological, thyroidal, bone metabolism, and hematopoietic pathways.

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Article Synopsis
  • Large-scale studies on gene-environment interactions often simplify outcomes and covariates to improve data consistency, which can hinder the understanding of complex relationships, such as those between physical activity and HDL cholesterol.* -
  • The study refined a previously identified interaction between the rs295849 genotype and physical activity on HDL cholesterol levels, using datasets from the Women's Genome Health Study, UK Biobank, and Multi-Ethnic Study of Atherosclerosis.* -
  • Findings showed that the interaction effect was stronger when looking at medium-sized HDL particles compared to total HDL cholesterol, highlighting variations based on gender and the specific lipid metrics used.*
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We construct non-linear machine learning (ML) prediction models for systolic and diastolic blood pressure (SBP, DBP) using demographic and clinical variables and polygenic risk scores (PRSs). We developed a two-model ensemble, consisting of a baseline model, where prediction is based on demographic and clinical variables only, and a genetic model, where we also include PRSs. We evaluate the use of a linear versus a non-linear model at both the baseline and the genetic model levels and assess the improvement in performance when incorporating multiple PRSs.

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Article Synopsis
  • Educational attainment is linked to cardiovascular health, and a large genomic study examined how it interacts with cholesterol and triglyceride levels in nearly 226,315 individuals across five population groups.
  • The study identified 18 new genetic variations related to lipid levels—nine for low-density lipoprotein (LDL), seven for high-density lipoprotein (HDL), and two for triglycerides (TG)—some of which interact with educational attainment.
  • Researchers also found five gene targets that potentially interact with FDA-approved drugs, suggesting a connection between genetics and drug responses related to lipid metabolism and overall health.
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  • Large-scale whole-genome sequencing (WGS) studies have enhanced our understanding of how rare genetic variants affect complex human traits through better analysis techniques.* -
  • Current methods for analyzing multiple traits are limited in their ability to handle rare variants in large WGS datasets, prompting the development of MultiSTAAR.* -
  • MultiSTAAR enables more powerful analysis by considering relatedness, population structure, and the correlation between traits, leading to the discovery of new genetic associations in lipid traits that single-trait analyses missed.*
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Objectives: Studies evaluating telemedicine critical care (TCC) have shown mixed results. We prospectively evaluated the impact of TCC implementation on risk-adjusted mortality among patients stratified by pre-TCC performance.

Design: Prospective, observational, before and after study.

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Article Synopsis
  • The study evaluates the effectiveness and shortcomings of polygenic risk scores (PRSs) in predicting various blood pressure (BP) phenotypes among different population groups, focusing on methods like "clumping-and-thresholding" (PRSice2) and LD-based (LDPred2).
  • It utilizes datasets from several biobanks, including MGB Biobank and UK Biobank, to train and validate PRSs based on self-reported race/ethnic backgrounds such as Asian, Black, Hispanic/Latino, and White.
  • Findings indicate that the PRS-CSx method, which combines weighted PRSs from multiple GWAS, provides the most accurate predictions across all racial/ethnic groups, with better effectiveness in females
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  • A study analyzed over 43,000 blood genomes and discovered 7,131 recurrent non-missense somatic mutations (RNMSMs) that frequently occur in at least 50 individuals, challenging the idea that such mutations are rare and insignificant.
  • RNMSMs were found to increase with age, averaging 27 mutations in individuals around 50 years old, and were linked to inherited genetic variations affecting immune functions.
  • The presence of specific RNMSMs was associated with blood cell traits similar to the effects of inherited genetic mutations, suggesting that these somatic mutations have significant implications for human health.
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Mutations in a diverse set of driver genes increase the fitness of haematopoietic stem cells (HSCs), leading to clonal haematopoiesis. These lesions are precursors for blood cancers, but the basis of their fitness advantage remains largely unknown, partly owing to a paucity of large cohorts in which the clonal expansion rate has been assessed by longitudinal sampling. Here, to circumvent this limitation, we developed a method to infer the expansion rate from data from a single time point.

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Elevated TNF-α levels in serum and broncho-alveolar lavage fluid of acute lung injury patients correlate with mortality rates. We hypothesized that pharmacological plasma membrane potential (Em) hyperpolarization protects against TNF-α-induced CCL-2 and IL-6 secretion from human pulmonary endothelial cells through inhibition of inflammatory Ca-dependent MAPK pathways. Since the role of Ca influx in TNF-α-mediated inflammation remains poorly understood, we explored the role of L-type voltage-gated Ca (Ca) channels in TNF-α-induced CCL-2 and IL-6 secretion from human pulmonary endothelial cells.

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Though both genetic and lifestyle factors are known to influence cardiometabolic outcomes, less attention has been given to whether lifestyle exposures can alter the association between a genetic variant and these outcomes. The Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium's Gene-Lifestyle Interactions Working Group has recently published investigations of genome-wide gene-environment interactions in large multi-ancestry meta-analyses with a focus on cigarette smoking and alcohol consumption as lifestyle factors and blood pressure and serum lipids as outcomes. Further description of the biological mechanisms underlying these statistical interactions would represent a significant advance in our understanding of gene-environment interactions, yet accessing and harmonizing individual-level genetic and 'omics data is challenging.

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Article Synopsis
  • Tobacco and alcohol use contribute significantly to global mortality rates, with heritability playing a key role in these behaviors.
  • This study utilized genetic data from a diverse population of 3.4 million individuals, including 21% non-European ancestry, to identify genetic variants linked to tobacco and alcohol use.
  • Findings showed that while increased genetic diversity improved the identification of genomic loci, polygenic risk scores were less effective across different ancestries, underscoring the need for larger and more diverse genetic datasets for better predictive outcomes.
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Influenza-A virus (IAV) infects yearly an estimated one billion people worldwide, resulting in 300,000-650,000 deaths. Preventive vaccination programs and antiviral medications represent the mainstay of therapy, but with unacceptably high morbidity and mortality rates, new targeted therapeutic approaches are urgently needed. Since inflammatory processes are commonly associated with measurable changes in the cell membrane potential (Em), we investigated whether Em hyperpolarization via TREK-1 () K channel activation can protect against influenza-A virus (IAV)-induced pneumonia.

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Article Synopsis
  • - Human genetic studies show that shorter leukocyte telomere length (LTL) is linked to a higher risk of coronary artery disease (CAD), while the relationship between LTL and various cancers is less clear.
  • - Clonal hematopoiesis of indeterminate potential (CHIP), which involves the growth of blood cells with certain mutations, increases the risk for both blood cancers and CAD, with telomerase reverse transcriptase being a key genetic factor in CHIP.
  • - Research from the TOPMed program and UK Biobank reveals that longer genetically predicted LTL increases the likelihood of developing CHIP, which then leads to a decrease in measured LTL, providing insights into how these factors might contribute to CAD prevention.
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The role and biological significance of gene-environment interactions in human traits and diseases remain poorly understood. To address these questions, the CHARGE Gene-Lifestyle Interactions Working Group conducted series of genome-wide interaction studies (GWIS) involving up to 610,475 individuals across four ancestries for three lipids and four blood pressure traits, while accounting for interaction effects with drinking and smoking exposures. Here we used GWIS summary statistics from these studies to decipher potential differences in genetic associations and G×E interactions across phenotype-exposure-ancestry combinations, and to derive insights on the potential mechanistic underlying G×E through in-silico functional analyses.

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Psychological and social factors are known to influence blood pressure (BP) and risk of hypertension and associated cardiovascular diseases. To identify novel BP loci, we carried out genome-wide association meta-analyses of systolic, diastolic, pulse, and mean arterial BP taking into account the interaction effects of genetic variants with three psychosocial factors: depressive symptoms, anxiety symptoms, and social support. Analyses were performed using a two-stage design in a sample of up to 128,894 adults from 5 ancestry groups.

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