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Short tandem repeat (STR) analysis, such as the AmpFlSTR® Identifiler® Plus kit, is a standard, PCR-based human genotyping method used in the field of forensics. Misidentification of cell line and tissue DNA can be costly if not detected early; therefore it is necessary to have quality control measures such as STR profiling in place. A major issue in large-scale research studies involving archival formalin-fixed paraffin embedded (FFPE) tissues is that varying levels of DNA degradation can result in failure to correctly identify samples using STR genotyping. PCR amplification of STRs of several hundred base pairs is not always possible when DNA is degraded. The Sample ID Plus® panel from Sequenom allows for human DNA identification and authentication using SNP genotyping. In comparison to lengthy STR amplicons, this multiplexing PCR assay requires amplification of only 76-139 base pairs, and utilizes 47 SNPs to discriminate between individual samples. In this study, we evaluated both STR and SNP genotyping methods of sample identification, with a focus on paired FFPE tumor/normal DNA samples intended for next-generation sequencing (NGS). The ability to successfully validate the identity of FFPE samples can enable cost savings by reducing rework.

Prostate tumours are highly variable in their response to therapies, but clinically available prognostic factors can explain only a fraction of this heterogeneity. Here we analysed 200 whole-genome sequences and 277 additional whole-exome sequences from localized, non-indolent prostate tumours with similar clinical risk profiles, and carried out RNA and methylation analyses in a subset. These tumours had a paucity of clinically actionable single nucleotide variants, unlike those seen in metastatic disease. Rather, a significant proportion of tumours harboured recurrent non-coding aberrations, large-scale genomic rearrangements, and alterations in which an inversion repressed transcription within its boundaries. Local hypermutation events were frequent, and correlated with specific genomic profiles. Numerous molecular aberrations were prognostic for disease recurrence, including several DNA methylation events, and a signature comprised of these aberrations outperformed well-described prognostic biomarkers. We suggest that intensified treatment of genomically aggressive localized prostate cancer may improve cure rates. Genomic analyses of localized, non-indolent prostate cancer identify recurrent aberrations that can predict relapse, and also highlight differences between early prostate cancer and metastatic, castration-resistant disease. Genomics of localized prostate cancer Robert Bristow, Paul Boutros and colleagues report genomic analyses of localized, non-indolent prostate cancer, which is a common disease state at initial clinical presentation that shows intermediate risk and cure rates. The analyses include 200 whole-genome and 477 whole-exome sequences of localized prostate cancer tumours, and analyses of copy-number alterations, genomic rearrangements and methylation. The authors highlight differences in mutational profiles between localized intermediate risk and metastatic, castrate-resistant prostate cancer.

Paul Boutros, Robert Bristow and colleagues report a molecular analysis of the spatial heterogeneity of clinically localized, multifocal prostate cancer. They find that multifocal tumors are highly heterogeneous, and they identify a novel recurrent amplification of MYCL1 . Herein we provide a detailed molecular analysis of the spatial heterogeneity of clinically localized, multifocal prostate cancer to delineate new oncogenes or tumor suppressors. We initially determined the copy number aberration (CNA) profiles of 74 patients with index tumors of Gleason score 7. Of these, 5 patients were subjected to whole-genome sequencing using DNA quantities achievable in diagnostic biopsies, with detailed spatial sampling of 23 distinct tumor regions to assess intraprostatic heterogeneity in focal genomics. Multifocal tumors are highly heterogeneous for single-nucleotide variants (SNVs), CNAs and genomic rearrangements. We identified and validated a new recurrent amplification of MYCL , which is associated with TP53 deletion and unique profiles of DNA damage and transcriptional dysregulation. Moreover, we demonstrate divergent tumor evolution in multifocal cancer and, in some cases, tumors of independent clonal origin. These data represent the first systematic relation of intraprostatic genomic heterogeneity to predicted clinical outcome and inform the development of novel biomarkers that reflect individual prognosis.

Pancreatic cancer is not caused by a specific series of genetic alterations that occur sequentially but by one, or few, catastrophic events that result in simultaneous oncogenic genetic rearrangements, giving rise to highly aggressive tumours. Pancreatic cancer genome evolution Pancreatic cancer is a highly aggressive tumour type. With a view to examining the evolution of rapid tumour progression in this cancer, this paper presents an analysis of more than a hundred tumour-enriched whole-genome sequences from primary and metastatic pancreas cancers obtained from collaborating hospitals in Canada and the United States of America. Challenging a traditional model of progressive evolution based on ordered mutations in several genes, the authors find support for a role of complex rearrangements and chromothripsis in pancreatic cancer progression, which suggests that the genomic instability that marks this cancer may be explained by a punctuated equilibrium model. Pancreatic cancer, a highly aggressive tumour type with uniformly poor prognosis, exemplifies the classically held view of stepwise cancer development 1 . The current model of tumorigenesis, based on analyses of precursor lesions, termed pancreatic intraepithelial neoplasm (PanINs) lesions, makes two predictions: first, that pancreatic cancer develops through a particular sequence of genetic alterations 2 , 3 , 4 , 5 ( KRAS , followed by CDKN2A , then TP53 and SMAD4 ); and second, that the evolutionary trajectory of pancreatic cancer progression is gradual because each alteration is acquired independently. A shortcoming of this model is that clonally expanded precursor lesions do not always belong to the tumour lineage 2 , 5 , 6 , 7 , 8 , 9 , indicating that the evolutionary trajectory of the tumour lineage and precursor lesions can be divergent. This prevailing model of tumorigenesis has contributed to the clinical notion that pancreatic cancer evolves slowly and presents at a late stage 10 . However, the propensity for this disease to rapidly metastasize and the inability to improve patient outcomes, despite efforts aimed at early detection 11 , suggest that pancreatic cancer progression is not gradual. Here, using newly developed informatics tools, we tracked changes in DNA copy number and their associated rearrangements in tumour-enriched genomes and found that pancreatic cancer tumorigenesis is neither gradual nor follows the accepted mutation order. Two-thirds of tumours harbour complex rearrangement patterns associated with mitotic errors, consistent with punctuated equilibrium as the principal evolutionary trajectory 12 . In a subset of cases, the consequence of such errors is the simultaneous, rather than sequential, knockout of canonical preneoplastic genetic drivers that are likely to set-off invasive cancer growth. These findings challenge the current progression model of pancreatic cancer and provide insights into the mutational processes that give rise to these aggressive tumours.

Jorge Reis-Filho and colleagues identify recurrent mutations in PRKD1 in 73% of polymorphous low-grade adenocarcinoma, a malignant tumor of the minor salivary glands. The mutations cause activation of the PRKD1 serine-threonine kinase. Polymorphous low-grade adenocarcinoma (PLGA) is the second most frequent type of malignant tumor of the minor salivary glands. We identified PRKD1 hotspot mutations encoding p.Glu710Asp in 72.9% of PLGAs but not in other salivary gland tumors. Functional studies demonstrated that this kinase-activating alteration likely constitutes a driver of PLGA.

Pancreas cancer (PC), a highly aggressive tumour type with uniformly poor prognosis, is an exemplar of the classical view of cancer development based on stepwise progression1. The current progression model, based on analyses of precursor lesions termed pancreatic intraepithelial neoplasm (PanINs) lesions, makes two predictions: 1) PC develops through a particular sequence of genetic alterations2–5 (KRAS > CDKN2A > TP53/SMAD4); and 2) the evolutionary trajectory of PC progression is gradual because each alteration is acquired independently. One shortcoming of this nearly two decade old contention is that clonally expanded precursor lesions have been identified that do not always belong to the tumour lineage2,5–9, indicating that the evolutionary trajectory of the tumour lineage and precursor lesions can be divergent. This prevailing view of tumourigenesis has contributed to the clinical notion that PC evolves slowly and presents at a late stage10. However, the propensity for this disease to rapidly metastasize and the inability to improve patient outcomes despite efforts aimed at early detection11, argue that PC progression is anything but gradual. By tracking DNA copy number changes and their associated rearrangements from tumour-enriched genomes using novel informatics tools, we found that PC tumourigenesis neither is gradual nor follows the accepted mutation order. Two-thirds of tumours harbour complex rearrangement patterns associated with mitotic errors, consistent with punctuated equilibrium as the principal evolutionary trajectory12. In a subset of cases, the consequence of such errors was the simultaneous, rather than sequential, knockout of canonical preneoplastic genetic drivers that likely set-off invasive cancer growth. These findings challenge the current model of PC tumourigenesis and provide novel insights into the mutational processes giving rise to these aggressive tumours.

Nature 538, 378–382 (2016); doi:10.1038/nature19823 In this Letter, owing to a typesetter error the ‘received date’ was incorrectly shown as ‘8 August 2015’ instead of ‘27 November 2015’ in both the print and PDF versions; this has been corrected online.

Pancreatic cancer is a highly lethal malignancy with few effective therapies. We performed exome sequencing and copy number analysis to define genomic aberrations in a prospectively accrued clinical cohort (n = 142) of early (stage I and II) sporadic pancreatic ductal adenocarcinoma. Detailed analysis of 99 informative tumours identified substantial heterogeneity with 2,016 non-silent mutations and 1,628 copy-number variations. We define 16 significantly mutated genes, reaffirming known mutations (KRAS, TP53, CDKN2A, SMAD4, MLL3, TGFBR2, ARID1A and SF3B1), and uncover novel mutated genes including additional genes involved in chromatin modification (EPC1 and ARID2), DNA damage repair (ATM) and other mechanisms (ZIM2, MAP2K4, NALCN, SLC16A4 and MAGEA6). Integrative analysis with in vitro functional data and animal models provided supportive evidence for potential roles for these genetic aberrations in carcinogenesis. Pathway-based analysis of recurrently mutated genes recapitulated clustering in core signalling pathways in pancreatic ductal adenocarcinoma, and identified new mutated genes in each pathway. We also identified frequent and diverse somatic aberrations in genes described traditionally as embryonic regulators of axon guidance, particularly SLIT/ROBO signalling, which was also evident in murine Sleeping Beauty transposon-mediated somatic mutagenesis models of pancreatic cancer, providing further supportive evidence for the potential involvement of axon guidance genes in pancreatic carcinogenesis. [PUBLICATION ABSTRACT]

ObjectivesThis study aimed to identify determinants of inappropriate antibiotic prescription in primary care in developed countries and to construct a framework with the determinants to help understand which actions can best be targeted to counteract development of antimicrobial resistance (AMR).DesignA systematic review of peer-reviewed studies reporting determinants of inappropriate antibiotic prescription published through 9 September 2021 in PubMed, Embase, Web of Science and the Cochrane Library was performed.SettingAll studies focusing on primary care in developed countries where general practitioners (GPs) act as gatekeepers for referral to medical specialists and hospital care were included.ResultsSeventeen studies fulfilled the inclusion criteria and were used for the analysis which identified 45 determinants of inappropriate antibiotic prescription. Important determinants for inappropriate antibiotic prescription were comorbidity, primary care not considered to be responsible for development of AMR and GP perception of patient desire for antibiotics. A framework was constructed with the determinants and provides a broad overview of several domains. The framework can be used to identify several reasons for inappropriate antibiotic prescription in a specific primary care setting and from there, choose the most suitable intervention(s) and assist in implementing them for combatting AMR.ConclusionsThe type of infection, comorbidity and the GPs perception of a patient’s desire for antibiotics are consistently identified as factors driving inappropriate antibiotic prescription in primary care. A framework with determinants of inappropriate antibiotic prescription may be useful after validation for effective implementation of interventions for decreasing these inappropriate prescriptions.PROSPERO registration numberCRD42023396225.

The etiology of eosinophilic esophagitis (EoE) is not well understood. It has been proposed that eosinophils migrate to the esophagus in response to various ingested and inhaled allergens. Recent reports in children found an increased proportion of cases of EoE during months with higher outdoor aeroallergens. To our knowledge, this has not been evaluated in adults. We aimed to determine whether there is a seasonal distribution in the number of newly diagnosed cases of EoE in an adult population. We conducted a retrospective review of consecutive adult cases newly diagnosed with EoE in 1 year. Cases were grouped based on the index month when the diagnosis was made at endoscopy. To test the consistency of the observations, a second cohort of consecutive cases of similar sample size diagnosed at a different period in time was also analyzed. In total, 41 patients were diagnosed with EoE at our center during the study period, providing an annual prevalence of 0.98%. More cases were diagnosed with EoE during the months of April and May than any other month (P<0.001). When patients were grouped seasonally, there was a significant increase of EoE cases in spring and summer months (n=28) when compared with the fall and winter months (n=13) (P=0.019). Analysis of the second cohort of cases (n=37) from 2002 to 2006 confirmed a similar seasonal diagnostic pattern for EoE during the outdoor seasons. Our data demonstrate that EoE has a seasonal prevalence in adults. The seasonal variation pattern found in newly diagnosed EoE cases in adults supports the potential role of aeroallergens in the pathogenesis of EoE.