Publications by authors named "Eric R Gamazon"

Root causal genes correspond to the first gene expression levels perturbed during pathogenesis by genetic or non-genetic factors. Targeting root causal genes has the potential to alleviate disease entirely by eliminating pathology near its onset. No existing algorithm has been designed to discover root causal genes from observational data alone.

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Introduction: Approaches for risk stratification in diverticulitis have emphasized lifestyle factors, with a possible emerging role for molecular signatures. We aimed to evaluate whether plasma proteomic profiles complement dietary and genetic factors in diverticulitis risk stratification.

Materials And Methods: This UK Biobank study derived a plasma proteomic risk score for severe diverticulitis (operative or recurrent inpatient disease).

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Striking disparities in lung cancer exist, with Black/African American individuals disproportionately affected by lung cancer, yet the genetic architecture in African ancestry individuals is poorly understood. We aimed to address this by performing a comprehensive genetic association study of lung cancer, incorporating local ancestry, across 6,490 African ancestry individuals (2,390 individuals with lung cancer and 4,100 control subjects). We identified a single genome-wide significant (p < 5 × 10) locus, 15q25.

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Familial Adult Myoclonic Epilepsy type 3 (FAME3) is a rare autosomal dominant disorder characterized by cortical tremor and epilepsy, caused by a noncoding pentanucleotide repeat expansion (TTTTA/TTTCA) in the MARCHF6 gene. Conventional genetic testing often fails to detect this expansion due to its repetitive structure and intronic location. We evaluated a 61-year-old woman with refractory myoclonic and generalized tonic-clonic seizures, whose prior genetic testing-including exome and genome sequencing-was non-diagnostic.

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Pressure overload initiates a series of alterations in the human heart that predate macroscopic organ-level remodeling and downstream heart failure. We study aortic stenosis through integrated proteomic, tissue transcriptomic, and genetic methods to prioritize targets causal in human heart failure. First, we identify the circulating proteome of cardiac remodeling in aortic stenosis, specifying known and previously-unknown mediators of fibrosis, hypertrophy, and oxidative stress, several associated with interstitial fibrosis in a separate cohort (N = 145).

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We characterized circulating extracellular vesicles (EVs) in obese and lean humans, identifying transcriptional cargo differentially expressed in obesity (277 unique genes; false discovery rate < 10%). Since circulating EVs may have broad origin, we compared this obesity EV transcriptome with expression from human visceral-adipose-tissue-derived EVs from freshly collected and cultured biopsies from the same obese individuals, observing high concordance. Using a comprehensive set of adipose-specific epigenomic and chromatin conformation assays, we found that the differentially expressed transcripts from the EVs were those regulated in adipose by body mass index-associated SNPs (p < 5 × 108) from a large-scale genome-wide association study (GWAS).

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Context: Efforts to characterize the shared molecular risk factors that contribute to obesity and the downstream disease sequelae it triggers have been limited.

Objective: We aimed to identify functional genes with evidence for both causal and consequential effects on obesity related traits and their downstream sequalae using integrated genomic and proteomic data.

Methods: We investigated the association of obesity related traits with 2,912 plasma proteins in 259 individuals from the Cameron County Hispanic Cohort (CCHC) with validation of results in ∼45,000 participants from UK Biobank (UKBB).

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Article Synopsis
  • The study investigates metabolic signatures related to insulin action and secretion in Indigenous Americans (IAs) and their link to diabetes.
  • Researchers analyzed data from nearly 2,000 IAs, looking at factors like glucose disposal rates and endogenous glucose production to identify connections with diabetes risk.
  • The findings indicate that specific metabolic profiles are strongly associated with diabetes onset, highlighting the role of fat and amino acid metabolism in a young population of IAs, and linking these profiles to genetic pathways involved in type 2 diabetes.
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Here, we present a multi-omics study of type 2 diabetes and quantitative blood lipid and lipoprotein traits conducted to date in Hispanic/Latino populations (n = 63,184). We conduct a meta-analysis of 16 type 2 diabetes and 19 lipid trait GWAS, identifying 20 genome-wide significant loci for type 2 diabetes, including one novel locus and novel signals at two known loci, based on fine-mapping. We also identify sixty-one genome-wide significant loci across the lipid/lipoprotein traits, including nine novel loci, and novel signals at 19 known loci through fine-mapping.

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The biological functions of extragenic enhancer RNAs and their impact on disease risk remain relatively underexplored. In this work, we develop in silico models of genetically regulated expression of enhancer RNAs across 49 cell and tissue types, characterizing their degree of genetic control. Leveraging the estimated genetically regulated expression for enhancer RNAs and canonical genes in a large-scale DNA biobank (N > 70,000) and high-resolution Hi-C contact data, we train a deep learning-based model of pairwise three-dimensional chromatin contact frequency for enhancer-enhancer and enhancer-gene pairs in cerebellum and whole blood.

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Our understanding of the influence of ancestral background on genetically determined expression remains limited, especially when gene expression models are applied to studies from different or multiple populations. We performed transcriptome wide association studies (TWAS) in 6 different psychiatric conditions, leveraging gene expression models trained in cohorts with different proportions of African, European, and Indigenous American genetic ancestries. For comparison we repeated each TWAS using a model trained in individuals of predominantly European ancestry.

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Current genetic discovery methods are largely restricted to profiling circulating molecules or genetic architecture, limited in use of tissue-based molecular genetics to identify pathogenic and therapeutic targets. Here, we leverage a multi-level genetic discovery platform integrating population-level proteomics with functional genomic analyses based on human coronary artery tissue to reveal determinants of coronary disease susceptibility. Using aptamer-based proteomics (~7,000 aptamers) across ~3,000 individuals, we first identified the circulating proteome of prevalent and incident coronary artery calcium (CAC), a sensitive marker of subclinical coronary artery disease (CAD), with causal implication in calcified plaque formation or disease phenotypes via parallel genetic approaches (Mendelian randomization, MR) and proteome-wide association (PWAS).

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Allograft rejection following solid-organ transplantation is a major cause of graft dysfunction and mortality. Current approaches to diagnosis rely on histology, which exhibits wide diagnostic variability and lacks access to molecular phenotypes that may stratify therapeutic response. Here, we leverage image-based spatial transcriptomics at sub-cellular resolution in longitudinal human cardiac biopsies to characterize transcriptional heterogeneity in 62 adult and pediatric heart transplant (HT) recipients during and following histologically-diagnosed rejection.

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Polygenic severe obesity (body mass index [BMI] ≥40 kg/m) has increased, especially in Hispanic/Latino populations, yet we know little about the underlying mechanistic pathways. We analyzed whole-blood multiomics data to identify genes differentially regulated in severe obesity in Mexican Americans from the Cameron County Hispanic Cohort. Our RNA sequencing analysis identified 124 genes significantly differentially expressed between severe obesity cases (BMI ≥40 kg/m) and controls (BMI <25 kg/m); 33% replicated in an independent sample from the same population.

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Single-cell transcriptome data can provide insights into how genetic variation influences biological processes involved in human physiology and disease. However, the identification of gene-level associations in distinct cell types faces several challenges, including the limited reference resources from population-scale studies, data sparsity in single-cell RNA sequencing, and the complex cell state pattern of expression within individual cell types. Here, we develop genetic models of cell-type-specific and cell-state-adjusted gene expression in mid-brain neurons undergoing differentiation from induced pluripotent stem cells.

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Hepatic steatosis is a central phenotype in multi-system metabolic dysfunction and is increasing in parallel with the obesity pandemic. We use a translational approach integrating clinical phenotyping and outcomes, circulating proteomics, and tissue transcriptomics to identify dynamic, functional biomarkers of hepatic steatosis. Using multi-modality imaging and broad proteomic profiling, we identify proteins implicated in the progression of hepatic steatosis that are largely encoded by genes enriched at the transcriptional level in the human liver.

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G6PC3 deficiency is a monogenic immunometabolic disorder that causes severe congenital neutropenia type 4. Patients display heterogeneous extra-hematological manifestations, contributing to delayed diagnosis. Here, we investigated the origin and functional consequence of the G6PC3 c.

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We characterized circulating extracellular vesicles (EVs) in obese and lean humans, identifying transcriptional cargo differentially expressed in obesity. Since circulating EVs may have broad origin, we compared this obesity EV transcriptome to expression from human visceral adipose tissue derived EVs from freshly collected and cultured biopsies from the same obese individuals. Using a comprehensive set of adipose-specific epigenomic and chromatin conformation assays, we found that the differentially expressed transcripts from the EVs were those regulated in adipose by BMI-associated SNPs from a large-scale GWAS.

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Article Synopsis
  • Microvascular dysfunction contributes to insulin resistance, particularly in individuals with a genetic variant (G allele) that reduces CD36 expression, impacting blood vessel function and glucose disposal.* -
  • Through various experimental methods, the study found that while CD36-deficient mice and humans showed improved insulin-stimulated glucose disposal, they had issues with blood volume response and vascular compliance, indicating a paradoxical relationship between microvascular resistance and insulin sensitivity.* -
  • The findings suggest that while CD36 deficiency may enhance glucose disposal efficiency, it simultaneously hampers the microvasculature's response to insulin, affecting oxygen delivery and energy metabolism in muscle and heart tissues.*
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Article Synopsis
  • NeuroimaGene is an R package that helps researchers find connections between genes and brain features related to mental health issues.
  • It allows users to study how specific genes affect brain structure and function and to visualize their findings easily.
  • By combining genetic data with brain imaging, the package improves our understanding of how genes influence brain health and diseases.
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The ability to track disease without tissue biopsy in patients is a major goal in biology and medicine. Here, we identify and characterize cardiomyocyte-derived extracellular vesicles in circulation (EVs; "cardiovesicles") through comprehensive studies of induced pluripotent stem cell-derived cardiomyocytes, genetic mouse models, and state-of-the-art mass spectrometry and low-input transcriptomics. These studies identified two markers (, ) enriched on cardiovesicles for biotinylated antibody-based immunocapture.

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  • Research highlights the genetic factors linked to schizophrenia (SCZ) through brain expression quantitative trait loci (eQTLs), primarily focusing on European populations, which limits insights into diverse populations.
  • A comparative analysis across African Americans, Europeans, and East Asians revealed distinct eQTL patterns, with over 343,000 eQTLs unique to non-European groups, largely driven by differences in allele frequency.
  • This study suggests that increasing diversity in genetic ancestry, rather than just sample size, can enhance understanding of SCZ's genetic basis and aid in identifying risk genes associated with the disorder.
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The Bone Morphogenetic Protein (BMP) signaling pathway is vital in neural progenitor cell proliferation, specification, and differentiation. The BMP signaling antagonist Gremlin 2 (Grem2) is the most potent natural inhibitor of BMP expressed in the adult brain; however its function remains unknown. To address this knowledge gap, we have analyzed mice lacking Grem2 via homologous recombination ( ).

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Background: Long QT syndrome is a lethal arrhythmia syndrome, frequently caused by rare loss-of-function variants in the potassium channel encoded by . Variant classification is difficult, often because of lack of functional data. Moreover, variant-based risk stratification is also complicated by heterogenous clinical data and incomplete penetrance.

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Objective: Polygenic risk scores (PRS) for diverticular disease must be evaluated in diverse cohorts. We sought to explore shared genetic predisposition across the phenome and to assess risk stratification in individuals genetically similar to European, African and Admixed-American reference samples.

Methods: A 44-variant PRS was applied to the Research Program.

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