Publications by authors named "Logan Walker"

Article Synopsis
  • Known genetic risk factors account for about one-third of familial endometrial cancer cases, but the link between rare germline copy number variants (CNVs) and cancer risk is not well understood.
  • A study analyzed DNA from over 4,000 endometrial cancer patients and nearly 18,000 controls, finding that the cancer group had a significantly higher number of CNVs.
  • The research identified 141 gene loci potentially related to endometrial cancer risk, highlighting a specific area (16p11.2) with recurrent deletions that could help further investigations into genetic susceptibility.
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RNAscope staining of breast cancer tissue allows pathologists to deduce genetic characteristics of the cancer by inspection at the microscopic level, which can lead to better diagnosis and treatment. Chromogenic RNAscope staining is easy to fit into existing pathology workflows, but manually analyzing the resulting tissue samples is time consuming. There is also a lack of peer-reviewed, performant solutions for automated analysis of chromogenic RNAscope staining.

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Article Synopsis
  • The ClinGen Hereditary Breast, Ovarian, and Pancreatic Cancer Variant Curation Expert Panel (HBOP VCEP) created specific guidelines for interpreting variants in the ATM gene, modifying the American College of Medical Genetics and Association for Molecular Pathology (ACMG/AMP) guidelines.
  • A pilot study testing 33 variants showed strong agreement between the VCEP classifications and existing ClinVar data, though some conflicting interpretations were clarified.
  • Overall, the modified rules led to 85% of the variants being classified more definitively, significantly enhancing the reliability of genetic interpretations related to the ATM gene.
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  • The ENIGMA research consortium focuses on determining the clinical significance of variants in hereditary breast and ovarian cancer genes, specifically BRCA1 and BRCA2, and evolved from an external expert panel to an internal Variant Curation Expert Panel (VCEP) to enhance alignment with FDA recognized classification processes.
  • The VCEP reviewed existing classification criteria and utilized statistical methods to assess evidence strength, testing new specifications on variants and updating documentation for better user clarity.
  • Analysis led to refined classifications for variants—resolving uncertainties and maintaining confidence in others—while revealing gaps in both ENIGMA's research and ACMG/AMP criteria, ultimately improving the classification process for BRCA1 and BRCA2 variants.
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The ClinGen Hereditary Breast, Ovarian and Pancreatic Cancer (HBOP) Variant Curation Expert Panel (VCEP) is composed of internationally recognized experts in clinical genetics, molecular biology and variant interpretation. This VCEP made specifications for ACMG/AMP guidelines for the ataxia telangiectasia mutated () gene according to the Food and Drug Administration (FDA)-approved ClinGen protocol. These gene-specific rules for were modified from the American College of Medical Genetics and Association for Molecular Pathology (ACMG/AMP) guidelines and were tested against 33 variants of various types and classifications in a pilot curation phase.

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The American College of Medical Genetics and Genomics (ACMG)/Association for Molecular Pathology (AMP) framework for classifying variants uses six evidence categories related to the splicing potential of variants: PVS1, PS3, PP3, BS3, BP4, and BP7. However, the lack of guidance on how to apply such codes has contributed to variation in the specifications developed by different Clinical Genome Resource (ClinGen) Variant Curation Expert Panels. The ClinGen Sequence Variant Interpretation Splicing Subgroup was established to refine recommendations for applying ACMG/AMP codes relating to splicing data and computational predictions.

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The American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) framework for classifying variants uses six evidence categories related to the splicing potential of variants: PVS1 (null variant in a gene where loss-of-function is the mechanism of disease), PS3 (functional assays show damaging effect on splicing), PP3 (computational evidence supports a splicing effect), BS3 (functional assays show no damaging effect on splicing), BP4 (computational evidence suggests no splicing impact), and BP7 (silent change with no predicted impact on splicing). However, the lack of guidance on how to apply such codes has contributed to variation in the specifications developed by different Clinical Genome Resource (ClinGen) Variant Curation Expert Panels. The ClinGen Sequence Variant Interpretation (SVI) Splicing Subgroup was established to refine recommendations for applying ACMG/AMP codes relating to splicing data and computational predictions.

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Characterizing the relationship between neuron spiking and the signals that electrodes record is vital to defining the neural circuits driving brain function and informing clinical brain-machine interface design. However, high electrode biocompatibility and precisely localizing neurons around the electrodes are critical to defining this relationship.Here, we demonstrate consistent localization of the recording site tips of subcellular-scale (6.

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Background: The mRNA splicing is regulated on multiple levels, resulting in the proper distribution of genes' transcripts in each cell and maintaining cell homeostasis. At the same time, the expression of alternative transcripts can change in response to underlying genetic variants, often missed during routine diagnostics.

Aim: The main aim of this study was to define the frequency of aberrant splicing in BRCA1 and BRCA2 genes in blood RNA extracted from ovarian cancer patients who were previously found negative for the presence of pathogenic alterations in the 25 most commonly analysed ovarian cancer genes, including BRCA1 and BRCA2.

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Modern high-throughput microscopy methods such as light-sheet imaging and electron microscopy are capable of producing petabytes of data inside of a single experiment. Storage of these large images, however, is challenging because of the difficulty of moving, storing, and analyzing such vast amounts of data, which is often collected at very high data rates (>1GBps). In this report, we provide a comparison of the performance of several compression algorithms using a collection of published and unpublished datasets including confocal, fMOST, and pathology images.

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The contribution of germline copy number variants (CNVs) to risk of developing cancer in individuals with pathogenic BRCA1 or BRCA2 variants remains relatively unknown. We conducted the largest genome-wide analysis of CNVs in 15,342 BRCA1 and 10,740 BRCA2 pathogenic variant carriers. We used these results to prioritise a candidate breast cancer risk-modifier gene for laboratory analysis and biological validation.

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Skipping of BRCA2 exon 3 (∆E3) is a naturally occurring splicing event, complicating clinical classification of variants that may alter ∆E3 expression. This study used multiple evidence types to assess pathogenicity of 85 variants in/near BRCA2 exon 3. Bioinformatically predicted spliceogenic variants underwent mRNA splicing analysis using minigenes and/or patient samples.

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The existence of "leukemia-initiating cells" (LICs) in chronic lymphocytic leukemia (CLL) remains controversial due to the difficulty in isolating and identifying the tumor-initiating cells. Here, we demonstrate a microchannel electroporation (MEP) microarray that injects RNA-detecting probes into single live cells, allowing the imaging and characterization of heterogeneous LICs by intracellular RNA expression. Using limited-cell FACS sequencing (LC-FACSeq), we can detect and monitor rare live LICs during leukemogenesis and characterize their differential drug sensitivity.

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An extreme chronic wound tissue microenvironment causes epigenetic gene silencing. An unbiased whole-genome methylome was studied in the wound-edge tissue of patients with chronic wounds. A total of 4,689 differentially methylated regions (DMRs) were identified in chronic wound-edge skin compared with unwounded human skin.

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In the spring of 2017, 2 adult lake sturgeon (LS) Acipenser fulvescens captured from the Wolf River, Wisconsin (USA), presented with multiple cutaneous plaques that, upon microscopic examination, indicated proliferative epidermitis. Ultrastructural examination of affected keratinocytes revealed particles in the nucleus having a morphology typical of herpesviruses. A degenerate PCR assay targeting the DNA polymerase catalytic subunit (pol) gene of large double-stranded DNA viruses generated amplicons of the anticipated size from skin samples, and sequences of amplicons confirmed the presence of a novel alloherpesvirus (lake sturgeon herpesvirus, LSHV) related to acipenserid herpesvirus 1 (AciHV1).

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The study of neuron morphology requires robust and comprehensive methods to quantify the differences between neurons of different subtypes and animal species. Several software packages have been developed for the analysis of neuron tracing results stored in the standard SWC format. The packages, however, provide relatively simple quantifications and their non-extendable architecture prohibit their use for advanced data analysis and visualization.

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Article Synopsis
  • * Over three years, we created an engaging curriculum using Jupyter notebooks to teach introductory Python for data science, inspired by The Carpentries' method of bite-sized lessons and hands-on practice.
  • * We aim to share our open curriculum with the education community, encouraging educators to utilize and enhance our resources available on GitHub.
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Multipotent neural stem cells (NSCs) are found in several isolated niches of the adult mammalian brain where they have unique potential to assist in tissue repair. Modern transcriptomics offer high-throughput methods for identifying disease or injury associated gene expression signatures in endogenous adult NSCs, but they require adaptation to accommodate the rarity of NSCs. Bulk RNA sequencing (RNAseq) of NSCs requires pooling several mice, which impedes application to labor-intensive injury models.

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Germline copy number variants (CNVs) are pervasive in the human genome but potential disease associations with rare CNVs have not been comprehensively assessed in large datasets. We analysed rare CNVs in genes and non-coding regions for 86,788 breast cancer cases and 76,122 controls of European ancestry with genome-wide array data. Gene burden tests detected the strongest association for deletions in BRCA1 (P = 3.

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Dysregulated cellular differentiation is a hallmark of acute leukemogenesis. Phosphatases are widely suppressed in cancers but have not been traditionally associated with differentiation. In this study, we found that the silencing of protein phosphatase 2A (PP2A) directly blocks differentiation in acute myeloid leukemia (AML).

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Identifying the cellular origins and mapping the dendritic and axonal arbors of neurons have been century old quests to understand the heterogeneity among these brain cells. Current Brainbow based transgenic animals take the advantage of multispectral labeling to differentiate neighboring cells or lineages, however, their applications are limited by the color capacity. To improve the analysis throughput, we designed Bitbow, a digital format of Brainbow which exponentially expands the color palette to provide tens of thousands of spectrally resolved unique labels.

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RNAscope®, has emerged as an important in-situ hybridisation method to validate mRNA expression within single cells whilst preserving tissue morphology in histological samples. The aim of this research was to compare the utility of various open-source and commercial image analysis methods, to quantify mRNA transcripts identified by RNAscope within formalin fixed paraffin embedded (FFPE) histological samples and cell monolayer preparations. Examination of MLH1 expression from 10 histological FFPE colorectal cancer specimens using four image analysis tools (Colour Deconvolution, SpotStudio, WEKA and the LEICA RNA-ISH algorithm) showed the WEKA tool as having the greatest level of agreement with manual quantification.

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Purpose: Inherited variants in the cancer susceptibility genes, BRCA1 and BRCA2 account for up to 5% of breast cancers. Multiple gene expression studies have analysed gene expression patterns that maybe associated with BRCA12 pathogenic variant status; however, results from these studies lack consensus. These studies have focused on the differences in population means to identified genes associated with BRCA1/2-carriers with little consideration for gene expression variability, which is also under genetic control and is a feature of cellular function.

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Article Synopsis
  • The Drosophila type II neuroblast lineages serve as a model for studying neurogenesis and differentiation, similar to processes in human brain development.
  • Targeted single-cell mRNA sequencing of third instar larval brains reveals 17 maturation stage markers, 30 markers for stem cell origin, and at least 12 neuronal subtypes.
  • The study provides resources like annotated gene correlation tables and a web tool (MiCV) to enhance the analysis of scRNA-seq datasets, advancing molecular understanding of neural differentiation.
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Article Synopsis
  • - GWAS has found over 180 genetic variants linked to breast cancer risk, but their functional impacts remain unclear; the researchers propose that gene expression variability might highlight key susceptibility genes.
  • - The study conducted veQTL analysis using GTEx data, identifying 70 significant associations, with 55 specific to breast tissue, pointing to a connection between genetic variants and gene expression in breast cancer.
  • - Four key genes involved in hormone biosynthesis were found to have increased variability linked to a specific high-risk breast cancer allele (A/A) in the FTO gene, suggesting this genetic variant might disrupt hormonal regulation and increase breast cancer risk.
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