Publications by authors named "Sharadha Sakthikumar"

A genomic understanding of the oncogenic processes and individual variability of human cancer has steadily fueled improvement in patient outcomes over the past 20 years. Mutations within tumour tissues are routinely assessed through clinical genomic diagnostic assays by academic and commercial laboratories to facilitate diagnosis, prognosis and effective treatment stratification. The application of genomics has unveiled a wealth of mutation-based biomarkers in canine cancers, suggesting that the transformative principles that have revolutionized human cancer medicine can be brought to bear in veterinary oncology.

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Background: Growing evidence from dogs and humans supports the abundance of mutation-based biomarkers in tumors of dogs. Increasing the use of clinical genomic diagnostic testing now provides another powerful data source for biomarker discovery.

Hypothesis: Analyzed clinical outcomes in dogs with cancer profiled using SearchLight DNA, a cancer gene panel for dogs, to identify mutations with prognostic value.

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Current knowledge of cancer genomics remains biased against noncoding mutations. To systematically search for regulatory noncoding mutations, we assessed mutations in conserved positions in the genome under the assumption that these are more likely to be functional than mutations in positions with low conservation. To this end, we use whole-genome sequencing data from the International Cancer Genome Consortium and combined it with evolutionary constraint inferred from 240 mammals, to identify genes enriched in noncoding constraint mutations (NCCMs), mutations likely to be regulatory in nature.

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The accrual of cancer mutation data and related functional and clinical associations have revolutionised human oncology, enabling the advancement of precision medicine and biomarker-guided clinical management. The catalogue of cancer mutations is also growing in canine cancers. However, without direct high-powered functional data in dogs, it remains challenging to interpret and utilise them in research and clinical settings.

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Article Synopsis
  • Thousands of genomic regions related to heritable human diseases have been identified, but understanding their biological significance remains challenging due to unclear functional importance.
  • An analysis using single-base phyloP scores from 240 mammals revealed that 3.3% of the human genome is significantly constrained, suggesting these areas are likely functionally important.
  • The study found that constrained positions correlate with variants that account for more common disease heritability than other functional annotations, indicating a need for further exploration of the human genome's regulatory landscape in relation to diseases.
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Although thousands of genomic regions have been associated with heritable human diseases, attempts to elucidate biological mechanisms are impeded by a general inability to discern which genomic positions are functionally important. Evolutionary constraint is a powerful predictor of function that is agnostic to cell type or disease mechanism. Here, single base phyloP scores from the whole genome alignment of 240 placental mammals identified 3.

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Objective: To evaluate the diagnostic, prognostic, and therapeutic utility of a cancer genomic diagnostic assay (SearchLight DNA; Vidium Animal Health) for diagnostically ambiguous cancer cases.

Animals: 69 privately owned dogs with ambiguous cancer diagnoses and for which the genomic assay was performed.

Procedures: Genomic assay reports generated between September 28, 2020, and July 31, 2022, for dogs with malignancy or suspected malignancy were reviewed to determine the assay's clinical utility defined as providing diagnostic clarity, prognostic information, and/or therapeutic options.

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Biological features of neoplastic disease affecting mammary gland tissue are shared between canines and humans. Research performed in either species has translational value and early phase clinical trials performed in canines with spontaneous disease could be informative for human trials. The purpose of this study was to investigate the somatic genetic aberrations occurring in canine mammary neoplasia by exome capture and next generation sequencing.

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The wheat leaf rust fungus, Puccinia triticina Erikss., is a worldwide pathogen of tetraploid durum and hexaploid wheat. Many races of P.

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Background: Glioblastoma (GBM) has one of the worst 5-year survival rates of all cancers. While genomic studies of the disease have been performed, alterations in the non-coding regulatory regions of GBM have largely remained unexplored. We apply whole-genome sequencing (WGS) to identify non-coding mutations, with regulatory potential in GBM, under the hypothesis that regions of evolutionary constraint are likely to be functional, and somatic mutations are likely more damaging than in unconstrained regions.

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Angiosarcoma is a highly aggressive cancer of blood vessel-forming cells with few effective treatment options and high patient mortality. It is both rare and heterogenous, making large, well-powered genomic studies nearly impossible. Dogs commonly suffer from a similar cancer, called hemangiosarcoma, with breeds like the golden retriever carrying heritable genetic factors that put them at high risk.

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Osteosarcoma is a debilitating bone cancer that affects humans, especially children and adolescents. A homologous form of osteosarcoma spontaneously occurs in dogs, and its differential incidence observed across breeds allows for the investigation of tumor mutations in the context of multiple genetic backgrounds. Using whole-exome sequencing and dogs from three susceptible breeds (22 golden retrievers, 21 Rottweilers, and 23 greyhounds), we found that osteosarcoma tumors show a high frequency of somatic copy-number alterations (SCNA), affecting key oncogenes and tumor-suppressor genes.

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var. is the causative agent of cryptococcal meningitis, a significant source of mortality in immunocompromised individuals, typically human immunodeficiency virus/AIDS patients from developing countries. Despite the worldwide emergence of this ubiquitous infection, little is known about the global molecular epidemiology of this fungal pathogen.

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The pathogenic species of are a major cause of mortality owing to severe infections in immunocompromised as well as immunocompetent individuals. Although antifungal treatment is usually effective, many patients relapse after treatment, and in such cases, comparative analyses of the genomes of incident and relapse isolates may reveal evidence of determinative, microevolutionary changes within the host. Here, we analyzed serial isolates cultured from cerebrospinal fluid specimens of 18 South African patients with recurrent cryptococcal meningitis.

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Leaf rust is one of the most common and damaging diseases of wheat, and is caused by an obligate biotrophic basidiomycete, (). In the present study, 20 isolates from Australia, comprising 10 phenotype-matched pairs with contrasting pathogenicity for , were analyzed using whole genome sequencing. Compared to the reference genome of the American isolate 1-1 BBBD Race 1, an average of 404,690 single nucleotide polymorphisms (SNPs) per isolate was found and the proportion of heterozygous SNPs was above 87% in the majority of the isolates, demonstrating a high level of polymorphism and a high rate of heterozygosity.

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The genus includes two species of thermally dimorphic fungi that cause paracoccidioidomycosis, a neglected health-threatening human systemic mycosis endemic to Latin America. To examine the genome evolution and the diversity of spp., we conducted whole-genome sequencing of 31 isolates representing the phylogenetic, geographic, and ecological breadth of the genus.

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Unlabelled: Cryptococcus gattii is a fungal pathogen of humans, causing pulmonary infections in otherwise healthy hosts. To characterize genomic variation among the four major lineages of C. gattii (VGI, -II, -III, and -IV), we generated, annotated, and compared 16 de novo genome assemblies, including the first for the rarely isolated lineages VGIII and VGIV.

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Article Synopsis
  • Candida albicans, a common fungus in the human gut, shows significant genetic diversity when analyzed through genomic and phenotypic methods on 21 clinical isolates.
  • The study found variations in chromosome structure and gene expression, with some strains exhibiting aneuploidy, which impacted their growth and fitness.
  • One isolate, P94015, displayed unique traits linked to a mutation in the EFG1 gene, resulting in changes that shifted its behavior from being pathogenic to more commensal.
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Advances in modern sequencing technologies allow us to generate sufficient data to analyze hundreds of bacterial genomes from a single machine in a single day. This potential for sequencing massive numbers of genomes calls for fully automated methods to produce high-quality assemblies and variant calls. We introduce Pilon, a fully automated, all-in-one tool for correcting draft assemblies and calling sequence variants of multiple sizes, including very large insertions and deletions.

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Blastomyces dermatitidis is a dimorphic fungal pathogen that primarily causes blastomycosis in the midwestern and northern United States and Canada. While the genes controlling sexual development have been known for a long time, the genes controlling sexual reproduction of B. dermatitidis (teleomorph, Ajellomyces dermatitidis) are unknown.

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Paracoccidioides is a fungal pathogen and the cause of paracoccidioidomycosis, a health-threatening human systemic mycosis endemic to Latin America. Infection by Paracoccidioides, a dimorphic fungus in the order Onygenales, is coupled with a thermally regulated transition from a soil-dwelling filamentous form to a yeast-like pathogenic form. To better understand the genetic basis of growth and pathogenicity in Paracoccidioides, we sequenced the genomes of two strains of Paracoccidioides brasiliensis (Pb03 and Pb18) and one strain of Paracoccidioides lutzii (Pb01).

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Rust fungi are some of the most devastating pathogens of crop plants. They are obligate biotrophs, which extract nutrients only from living plant tissues and cannot grow apart from their hosts. Their lifestyle has slowed the dissection of molecular mechanisms underlying host invasion and avoidance or suppression of plant innate immunity.

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Article Synopsis
  • Fusarium species are significant fungi that cause plant diseases and produce toxins.
  • Our study compared the genomes of three different Fusarium species, highlighting unique genomic regions in Fusarium oxysporum that are linked to its ability to cause disease.
  • We found that the transfer of specific genomic regions can convert non-pathogenic strains into pathogens, suggesting that the evolution of pathogenicity in these fungi is influenced by the exchange of genetic material.
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Candida species are the most common cause of opportunistic fungal infection worldwide. Here we report the genome sequences of six Candida species and compare these and related pathogens and non-pathogens. There are significant expansions of cell wall, secreted and transporter gene families in pathogenic species, suggesting adaptations associated with virulence.

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