Publications by authors named "Mitchell Machiela"

Previous epidemiological studies have reported increased risks of certain cancers in relation to pesticide exposures. Although the biologic mechanisms underlying these associations are not well understood, altered telomere length has been hypothesized to play a role. We examined associations between occupational use of specific pesticides and leukocyte telomere length in the Biomarkers of Exposure and Effect in Agriculture study, a molecular epidemiological investigation of pesticide applicators in Iowa and North Carolina.

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Background: Mosaic loss of the Y chromosome (mLOY) in circulating leukocytes is the most frequently detected age-related chromosomal mosaic event in men. Current mLOY detection approaches use genotyping arrays and employ a phase-based approach that identifies B allele frequency (BAF) deviations in the pseudo-autosomal region (PAR) shared between the X and Y chromosome. As some widely used genotyping arrays lack sufficient probe coverage of the PAR, methods for accurately measuring mLOY utilizing the median log R ratio across the male-specific region of Y chromosome (mLRR_Y) are needed for detecting mLOY on these platforms.

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The chromosome 5p15.33 region, which encodes telomerase reverse transcriptase (TERT), harbors multiple germline variants identified by genome-wide association studies (GWAS) as risk for some cancers but protective for others. Here, we characterize a variable number tandem repeat within TERT intron 6, VNTR6-1 (38-bp repeat unit), and detect a strong link between VNTR6-1 alleles (Short: 24-27 repeats, Long: 40.

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We conducted a multiancestry genome-wide association study of prostate-specific antigen (PSA) levels in 296,754 men (211,342 European ancestry, 58,236 African ancestry, 23,546 Hispanic/Latino and 3,630 Asian ancestry; 96.5% of participants were from the Million Veteran Program). We identified 318 independent genome-wide significant (P ≤ 5 × 10) variants, 184 of which were novel.

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Obesity strongly increases the risk of cardiometabolic diseases, yet the underlying mediators of this relationship are not fully understood. Given that obesity strongly influences circulating protein levels, we investigated proteins mediating the effects of obesity on coronary artery disease, stroke and type 2 diabetes. By integrating two-step proteome-wide Mendelian randomization, colocalization, epigenomics and single-cell RNA sequencing, we identified five mediators and prioritized collagen type VI α3 (COL6A3).

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Mosaic loss of Y (mLOY) is the most common somatic chromosomal alteration detected in human blood. The presence of mLOY is associated with altered blood cell counts and increased risk of Alzheimer disease, solid tumors, and other age-related diseases. We sought to gain a better understanding of genetic drivers and associated phenotypes of mLOY through analyses of whole-genome sequencing (WGS) of a large set of genetically diverse males from the Trans-Omics for Precision Medicine (TOPMed) program.

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Genome-wide association studies (GWAS) of melanoma risk have identified 68 independent signals at 54 loci. For most loci, specific functional variants and their respective target genes remain to be established. Capture-HiC is an assay that links fine-mapped risk variants to candidate target genes by comprehensively mapping cell-type specific chromatin interactions.

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The chromosome 5p15.33 region, which encodes telomerase reverse transcriptase (TERT), harbors multiple germline variants identified by genome-wide association studies (GWAS) as risk for some cancers but protective for others. We characterized a variable number tandem repeat within intron 6 (VNTR6-1, 38-bp repeat unit) and observed a strong association between VNTR6-1 alleles (Short: 24-27 repeats, Long: 40.

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Deletion of the long q arm of chromosome 22 (22qDEL) is the most frequently identified recurrent somatic copy number alteration observed in papillary thyroid carcinoma (PTC). Since its role in PTC is not fully understood, we conducted a pooled analysis of genomic characteristics and clinical correlates in 1094 primary tumors from four published PTC genomic studies. The majority of PTC cases with 22qDEL exhibited arm-level loss of heterozygosity (86%); nearly all PTC cases with 22qDEL had losses in 22q12 and 13, which together constitute 70% of the q arm.

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Background: Mosaic loss of chromosome Y (mLOY) in leukocytes of men reflects genomic instability from aging, smoking, and environmental exposures. A similar mosaic loss of chromosome X (mLOX) occurs among women. However, the associations between mLOY, mLOX, and risk of incident heart diseases are unclear.

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Background: Risk factors including smoking, alcohol intake, physical activity (PA), and sleep patterns have been associated with cancer risk. Clonal hematopoiesis (CH), including mosaic chromosomal alterations and clonal hematopoiesis of indeterminate potential, is linked to increased hematopoietic cancer risk and could be used as common preclinical intermediates for the better understanding of associations of risk factors with rare hematologic malignancies.

Methods: We analyzed cross-sectional data from 478,513 UK Biobank participants without hematologic malignancies using multivariable-adjusted analyses to assess the associations between lifestyle factors and CH types.

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We performed a series of integrative analyses including transcriptome-wide association studies (TWASs) and proteome-wide association studies (PWASs) of renal cell carcinoma (RCC) to nominate and prioritize molecular targets for laboratory investigation. On the basis of a genome-wide association study (GWAS) of 29,020 affected individuals and 835,670 control individuals and prediction models trained in transcriptomic reference models, our TWAS across four kidney transcriptomes (GTEx kidney cortex, kidney tubules, TCGA-KIRC [The Cancer Genome Atlas kidney renal clear-cell carcinoma], and TCGA-KIRP [TCGA kidney renal papillary cell carcinoma]) identified 38 gene associations (false-discovery rate <5%) in at least two of four transcriptomic panels and identified 12 genes that were independent of GWAS susceptibility regions. Analyses combining TWAS associations across 48 tissues from GTEx identified associations that were replicable in tumor transcriptomes for 23 additional genes.

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Article Synopsis
  • * The newly developed multi-ancestry PRS showed a strong correlation with LUAD risk, indicating that individuals in the highest PRS percentile had significantly increased risk compared to those in the lowest.
  • * Findings suggest that those in the highest risk category have a lifetime risk of about 6.69%, and they reach the average population's 10-year risk for LUAD by age 41, highlighting the importance of multi-ancestry PRS for better risk assessment in this group.
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Background: Mosaic loss of chromosome Y (mLOY) in leukocytes of men reflects genomic instability from aging, smoking, and environmental exposures. A similar mosaic loss of chromosome X (mLOX) occurs among women. However, the associations between mLOY, mLOX, and risk of incident heart diseases are unclear.

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  • Childhood exposure to radioactive iodine from the Chornobyl accident increases the risk of papillary thyroid carcinoma (PTC), particularly in younger individuals.
  • A study of 428 PTC cases found that cervical lymph node metastases (cLNM) were more common in PTC with certain genetic fusions compared to mutations, and this frequency varied significantly by specific gene types.
  • Molecular profiling of the cLNM showed strong genetic concordance with primary PTCs and identified 17 differentially expressed genes, pointing to potential biological mechanisms in PTC metastasis that require further investigation.
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  • Mosaic loss of the X chromosome (mLOX) is a common genetic alteration in female leukocytes, found in 12% of a study involving 883,574 female participants, with around 2% of their leukocytes showing this alteration.
  • Female individuals with mLOX have a higher risk of developing myeloid and lymphoid leukemias, and genetic studies revealed 56 common variants linked to mLOX, pointing towards genes involved in chromosomal errors and diseases.
  • The research also found specific rare genetic variants that significantly increase the risk of mLOX and demonstrated how certain X chromosome alleles are preferentially retained, suggesting that both genetic predispositions and selective pressures play a role in the development and growth
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  • The study investigates the genetic factors influencing levels of prostate-specific antigen (PSA), which could enhance its effectiveness for prostate cancer screening among men.
  • Researchers conducted a transcriptome-wide association study (TWAS) using data from nearly 100,000 prostate cancer-free men, identifying 173 unique genes associated with PSA levels, with 151 resembling findings in another large dataset.
  • Further analysis revealed 20 genes that influenced PSA levels independently from identified genetic variants, with several showing a potential causal relationship and the need for additional research to understand these genetic influences better.
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Mosaic loss of Y (mLOY) is the most common somatic chromosomal alteration detected in human blood. The presence of mLOY is associated with altered blood cell counts and increased risk of Alzheimer's disease, solid tumors, and other age-related diseases. We sought to gain a better understanding of genetic drivers and associated phenotypes of mLOY through analyses of whole genome sequencing of a large set of genetically diverse males from the Trans-Omics for Precision Medicine (TOPMed) program.

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Here, in a multi-ancestry genome-wide association study meta-analysis of kidney cancer (29,020 cases and 835,670 controls), we identified 63 susceptibility regions (50 novel) containing 108 independent risk loci. In analyses stratified by subtype, 52 regions (78 loci) were associated with clear cell renal cell carcinoma (RCC) and 6 regions (7 loci) with papillary RCC. Notably, we report a variant common in African ancestry individuals ( rs7629500 ) in the 3' untranslated region of VHL, nearly tripling clear cell RCC risk (odds ratio 2.

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Motivation: The acquisition of somatic mutations in hematopoietic stem and progenitor stem cells with resultant clonal expansion, termed clonal hematopoiesis (CH), is associated with increased risk of hematologic malignancies and other adverse outcomes. CH is generally present at low allelic fractions, but clonal expansion and acquisition of additional mutations leads to hematologic cancers in a small proportion of individuals. With high depth and high sensitivity sequencing, CH can be detected in most adults and its clonal trajectory mapped over time.

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  • * Our findings showed a clear dose-response link where longer LTL and gTL were associated with an increased risk of lung cancer, especially adenocarcinoma, with strong associations noted among those who have never smoked.
  • * Mendelian Randomization analyses indicated a causal relationship, suggesting that longer telomere length significantly raises lung cancer risk (HR=1.87), particularly for adenocarcinoma (HR=2.45).
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The majority of disease-associated variants identified through genome-wide association studies are located outside of protein-coding regions. Prioritizing candidate regulatory variants and gene targets to identify potential biological mechanisms for further functional experiments can be challenging. To address this challenge, we developed FORGEdb ( https://forgedb.

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