Author
Tammie Dewan
Other affiliations: Family Research Institute
Bio: Tammie Dewan is an academic researcher from University of British Columbia. The author has contributed to research in topics: Medicine & Pediatrics. The author has an hindex of 5, co-authored 9 publications receiving 371 citations. Previous affiliations of Tammie Dewan include Family Research Institute.
Topics: Medicine, Pediatrics, Retrospective cohort study, Population, Cohort
Papers
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University of British Columbia1, Family Research Institute2, Simon Fraser University3, King Saud bin Abdulaziz University for Health Sciences4, University of Zurich5, University of Alberta6, University of Edinburgh7, National Research Council8, Arabian Gulf University9, University of Lausanne10, University of Texas at Austin11, Aristotle University of Thessaloniki12, Radboud University Nijmegen13
TL;DR: Deep phenotyping and whole-exome sequencing in 41 probands with intellectual developmental disorder and unexplained metabolic abnormalities led to a diagnosis in 68%, the identification of 11 candidate genes newly implicated in neurometabolic disease, and a change in treatment beyond genetic counseling in 44%.
Abstract: BackgroundWhole-exome sequencing has transformed gene discovery and diagnosis in rare diseases. Translation into disease-modifying treatments is challenging, particularly for intellectual developmental disorder. However, the exception is inborn errors of metabolism, since many of these disorders are responsive to therapy that targets pathophysiological features at the molecular or cellular level. MethodsTo uncover the genetic basis of potentially treatable inborn errors of metabolism, we combined deep clinical phenotyping (the comprehensive characterization of the discrete components of a patient’s clinical and biochemical phenotype) with whole-exome sequencing analysis through a semiautomated bioinformatics pipeline in consecutively enrolled patients with intellectual developmental disorder and unexplained metabolic phenotypes. ResultsWe performed whole-exome sequencing on samples obtained from 47 probands. Of these patients, 6 were excluded, including 1 who withdrew from the study. The remaining 41 prob...
231 citations
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University of British Columbia1, University of Lausanne2, St. Michael's Hospital3, University of Toronto4, Radboud University Nijmegen5, Central Manchester University Hospitals NHS Foundation Trust6, Necker-Enfants Malades Hospital7, Children's Medical Center of Dallas8, University of Pavia9, University of Zurich10, Swiss Institute of Bioinformatics11, Austrian Academy of Sciences12, Medical University of Vienna13, Boston Children's Hospital14
TL;DR: It was found that Knockdown of nansa in zebrafish embryos resulted in abnormal skeletal development, and exogenously added sialic acid partially rescued the skeletal phenotype, and NANS-mediated synthesis of siala is required for early brain development and skeletal growth.
Abstract: We identified biallelic mutations in NANS, the gene encoding the synthase for N-acetylneuraminic acid (NeuNAc; sialic acid), in nine individuals with infantile-onset severe developmental delay and skeletal dysplasia. Patient body fluids showed an elevation in N-acetyl-D-mannosamine levels, and patient-derived fibroblasts had reduced NANS activity and were unable to incorporate sialic acid precursors into sialylated glycoproteins. Knockdown of nansa in zebrafish embryos resulted in abnormal skeletal development, and exogenously added sialic acid partially rescued the skeletal phenotype. Thus, NANS-mediated synthesis of sialic acid is required for early brain development and skeletal growth. Normal sialylation of plasma proteins was observed in spite of NANS deficiency. Exploration of endogenous synthesis, nutritional absorption, and rescue pathways for sialic acid in different tissues and developmental phases is warranted to design therapeutic strategies to counteract NANS deficiency and to shed light on sialic acid metabolism and its implications for human nutrition.
122 citations
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TL;DR: The paediatric community should engage in health care reform discussions focused on chronic disease to ensure that the complex needs of these children are met.
89 citations
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University of Nantes1, Centre Hospitalier Universitaire Sainte-Justine2, Royal Melbourne Hospital3, AstraZeneca4, University of Oxford5, GeneDx6, Mayo Clinic7, University of California, San Francisco8, French Institute of Health and Medical Research9, Johns Hopkins University School of Medicine10, Kennedy Krieger Institute11, Chapel Allerton Hospital12, University of British Columbia13, University of Dundee14, Rush University Medical Center15, Paris Descartes University16, University of Virginia17, Boston Children's Hospital18, Baylor College of Medicine19, Baylor University20, University of Pennsylvania21, Children's Hospital of Philadelphia22, National Institutes of Health23, Karolinska Institutet24, Karolinska University Hospital25, Duke University26, University Medical Center Groningen27, Radboud University Nijmegen28, University of Arkansas for Medical Sciences29, University of Texas System30, Columbia University31, Royal Brisbane and Women's Hospital32, University of Queensland33, University of Washington34, Oslo University Hospital35, Necker-Enfants Malades Hospital36, Children's Memorial Hospital37, François Rabelais University38, University of Rennes39, Centre national de la recherche scientifique40, University of Poitiers41, University of Alberta42, McGill University43, Creighton University44, Howard Hughes Medical Institute45, Université de Montréal46
TL;DR: The clinical spectrum associated with TRRAP pathogenic missense variants is described, and a genotype-phenotype correlation useful for clinical evaluation of the pathogenicity of the variants is suggested.
Abstract: Acetylation of the lysine residues in histones and other DNA-binding proteins plays a major role in regulation of eukaryotic gene expression. This process is controlled by histone acetyltransferases (HATs/KATs) found in multiprotein complexes that are recruited to chromatin by the scaffolding subunit transformation/transcription domain-associated protein (TRRAP). TRRAP is evolutionarily conserved and is among the top five genes intolerant to missense variation. Through an international collaboration, 17 distinct de novo or apparently de novo variants were identified in TRRAP in 24 individuals. A strong genotype-phenotype correlation was observed with two distinct clinical spectra. The first is a complex, multi-systemic syndrome associated with various malformations of the brain, heart, kidneys, and genitourinary system and characterized by a wide range of intellectual functioning; a number of affected individuals have intellectual disability (ID) and markedly impaired basic life functions. Individuals with this phenotype had missense variants clustering around the c.3127G>A p.(Ala1043Thr) variant identified in five individuals. The second spectrum manifested with autism spectrum disorder (ASD) and/or ID and epilepsy. Facial dysmorphism was seen in both groups and included upslanted palpebral fissures, epicanthus, telecanthus, a wide nasal bridge and ridge, a broad and smooth philtrum, and a thin upper lip. RNA sequencing analysis of skin fibroblasts derived from affected individuals skin fibroblasts showed significant changes in the expression of several genes implicated in neuronal function and ion transport. Thus, we describe here the clinical spectrum associated with TRRAP pathogenic missense variants, and we suggest a genotype-phenotype correlation useful for clinical evaluation of the pathogenicity of the variants.
25 citations
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TL;DR: Age and higher ferritin levels were associated with more severe MIS-C later in the study period, and the risk of ICU admission was significantly higher for children admitted to hospital between December 2020 and March 2021 than those admitted between March and May 2020.
Abstract: Background: SARS-CoV-2 infection can lead to multisystem inflammatory syndrome in children (MIS-C). We sought to investigate risk factors for admission to the intensive care unit (ICU) and explored changes in disease severity over time. Methods: We obtained data from chart reviews of children younger than 18 years with confirmed or probable MIS-C who were admitted to 15 hospitals in Canada, Iran and Costa Rica between Mar. 1, 2020, and Mar. 7, 2021. Using multivariable analyses, we evaluated whether admission date and other characteristics were associated with ICU admission or cardiac involvement. Results: Of 232 children with MIS-C (median age 5.8 yr), 130 (56.0%) were male and 50 (21.6%) had comorbidities. Seventy-three (31.5%) patients were admitted to the ICU but none died. We observed an increased risk of ICU admission among children aged 13–17 years (adjusted risk difference 27.7%, 95% confidence interval [CI] 8.3% to 47.2%), those aged 6–12 years (adjusted risk difference 25.2%, 95% CI 13.6% to 36.9%) or those with initial ferritin levels greater than 500 μg/L (adjusted risk difference 18.4%, 95% CI 5.6% to 31.3%). Children admitted to hospital after Oct. 31, 2020, had numerically higher rates of ICU admission (adjusted risk difference 12.3%, 95% CI −0.3% to 25.0%) and significantly higher rates of cardiac involvement (adjusted risk difference 30.9%, 95% CI 17.3% to 44.4%). At Canadian sites, the risk of ICU admission was significantly higher for children admitted to hospital between December 2020 and March 2021 than those admitted between March and May 2020 (adjusted risk difference 25.3%, 95% CI 6.5% to 44.0%). Interpretation: We observed that age and higher ferritin levels were associated with more severe MIS-C. We observed greater severity of MIS-C later in the study period. Whether emerging SARS-CoV-2 variants pose different risks of severe MIS-C needs to be determined.
15 citations
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01 Jan 2011
TL;DR: The sheer volume and scope of data posed by this flood of data pose a significant challenge to the development of efficient and intuitive visualization tools able to scale to very large data sets and to flexibly integrate multiple data types, including clinical data.
Abstract: Rapid improvements in sequencing and array-based platforms are resulting in a flood of diverse genome-wide data, including data from exome and whole-genome sequencing, epigenetic surveys, expression profiling of coding and noncoding RNAs, single nucleotide polymorphism (SNP) and copy number profiling, and functional assays. Analysis of these large, diverse data sets holds the promise of a more comprehensive understanding of the genome and its relation to human disease. Experienced and knowledgeable human review is an essential component of this process, complementing computational approaches. This calls for efficient and intuitive visualization tools able to scale to very large data sets and to flexibly integrate multiple data types, including clinical data. However, the sheer volume and scope of data pose a significant challenge to the development of such tools.
2,187 citations
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TL;DR: It is time for the diverse functional roles of glycans to be fully incorporated into the mainstream of biological sciences, as they are no different from other major macromolecular building blocks of life, simply more rapidly evolving and complex.
Abstract: Simple and complex carbohydrates (glycans) have long been known to play major metabolic, structural and physical roles in biological systems. Targeted microbial binding to host glycans has also been studied for decades. But such biological roles can only explain some of the remarkable complexity and organismal diversity of glycans in nature. Reviewing the subject about two decades ago, one could find very few clear-cut instances of glycan-recognition-specific biological roles of glycans that were of intrinsic value to the organism expressing them. In striking contrast there is now a profusion of examples, such that this updated review cannot be comprehensive. Instead, a historical overview is presented, broad principles outlined and a few examples cited, representing diverse types of roles, mediated by various glycan classes, in different evolutionary lineages. What remains unchanged is the fact that while all theories regarding biological roles of glycans are supported by compelling evidence, exceptions to each can be found. In retrospect, this is not surprising. Complex and diverse glycans appear to be ubiquitous to all cells in nature, and essential to all life forms. Thus, >3 billion years of evolution consistently generated organisms that use these molecules for many key biological roles, even while sometimes coopting them for minor functions. In this respect, glycans are no different from other major macromolecular building blocks of life (nucleic acids, proteins and lipids), simply more rapidly evolving and complex. It is time for the diverse functional roles of glycans to be fully incorporated into the mainstream of biological sciences.
1,588 citations
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TL;DR: Exome sequencing in a combined cohort of more than 3000 patients with chronic kidney disease yielded a genetic diagnosis in just under 10% of cases, with genetic findings for medically actionable disorders that would also lead to subspecialty referral and inform renal management.
Abstract: Background Exome sequencing is emerging as a first-line diagnostic method in some clinical disciplines, but its usefulness has yet to be examined for most constitutional disorders in adult...
409 citations
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TL;DR: In children with suspected genetic diseases, the diagnostic and clinical utility of WGS/WES were greater than CMA, and WGS should be considered a first-line genomic test for children with suspect genetic diseases.
Abstract: Genetic diseases are leading causes of childhood mortality. Whole-genome sequencing (WGS) and whole-exome sequencing (WES) are relatively new methods for diagnosing genetic diseases, whereas chromosomal microarray (CMA) is well established. Here we compared the diagnostic utility (rate of causative, pathogenic, or likely pathogenic genotypes in known disease genes) and clinical utility (proportion in whom medical or surgical management was changed by diagnosis) of WGS, WES, and CMA in children with suspected genetic diseases by systematic review of the literature (January 2011–August 2017) and meta-analysis, following MOOSE/PRISMA guidelines. In 37 studies, comprising 20,068 children, diagnostic utility of WGS (0.41, 95% CI 0.34–0.48, I2 = 44%) and WES (0.36, 95% CI 0.33–0.40, I2 = 83%) were qualitatively greater than CMA (0.10, 95% CI 0.08–0.12, I2 = 81%). Among studies published in 2017, the diagnostic utility of WGS was significantly greater than CMA (P < 0.0001, I2 = 13% and I2 = 40%, respectively). Among studies featuring within-cohort comparisons, the diagnostic utility of WES was significantly greater than CMA (P < 0.001, I2 = 36%). The diagnostic utility of WGS and WES were not significantly different. In studies featuring within-cohort comparisons of WGS/WES, the likelihood of diagnosis was significantly greater for trios than singletons (odds ratio 2.04, 95% CI 1.62–2.56, I2 = 12%; P < 0.0001). Diagnostic utility of WGS/WES with hospital-based interpretation (0.42, 95% CI 0.38–0.45, I2 = 48%) was qualitatively higher than that of reference laboratories (0.29, 95% CI 0.27–0.31, I2 = 49%); this difference was significant among studies published in 2017 (P < .0001, I2 = 22% and I2 = 26%, respectively). The clinical utility of WGS (0.27, 95% CI 0.17–0.40, I2 = 54%) and WES (0.17, 95% CI 0.12–0.24, I2 = 76%) were higher than CMA (0.06, 95% CI 0.05–0.07, I2 = 42%); this difference was significant for WGS vs CMA (P < 0.0001). In conclusion, in children with suspected genetic diseases, the diagnostic and clinical utility of WGS/WES were greater than CMA. Subgroups with higher WGS/WES diagnostic utility were trios and those receiving hospital-based interpretation. WGS/WES should be considered a first-line genomic test for children with suspected genetic diseases.
381 citations
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TL;DR: For affected families, a better understanding of the genetic basis of rare disease translates to more accurate prognosis, management, surveillance and genetic advice; stimulates research into new therapies; and enables provision of better support.
Abstract: The majority of rare diseases affect children, most of whom have an underlying genetic cause for their condition However, making a molecular diagnosis with current technologies and knowledge is often still a challenge Paediatric genomics is an immature but rapidly evolving field that tackles this issue by incorporating next-generation sequencing technologies, especially whole-exome sequencing and whole-genome sequencing, into research and clinical workflows This complex multidisciplinary approach, coupled with the increasing availability of population genetic variation data, has already resulted in an increased discovery rate of causative genes and in improved diagnosis of rare paediatric disease Importantly, for affected families, a better understanding of the genetic basis of rare disease translates to more accurate prognosis, management, surveillance and genetic advice; stimulates research into new therapies; and enables provision of better support
364 citations