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BACKGROUND: Whole blood is currently the most common DNA source for whole-genome sequencing (WGS), but for studies requiring non-invasive collection, self-collection, greater sample stability or additional tissue references, saliva or buccal samples may be preferred. However, the relative quality of sequencing data and accuracy of genetic variant detection from blood-derived, saliva-derived and buccal-derived DNA need to be thoroughly investigated. METHODS: Matched blood, saliva and buccal samples from four unrelated individuals were used to compare sequencing metrics and variant-detection accuracy among these DNA sources. RESULTS: We observed significant differences among DNA sources for sequencing quality metrics such as percentage of reads aligned and mean read depth (p<0.05). Differences were negligible in the accuracy of detecting short insertions and deletions; however, the false positive rate for single nucleotide variation detection was slightly higher in some saliva and buccal samples. The sensitivity of copy number variant (CNV) detection was up to 25% higher in blood samples, depending on CNV size and type, and appeared to be worse in saliva and buccal samples with high bacterial concentration. We also show that methylation-based enrichment for eukaryotic DNA in saliva and buccal samples increased alignment rates but also reduced read-depth uniformity, hampering CNV detection. CONCLUSION: For WGS, we recommend using DNA extracted from blood rather than saliva or buccal swabs; if saliva or buccal samples are used, we recommend against using methylation-based eukaryotic DNA enrichment. All data used in this study are available for further open-science investigation.
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Variaciones en el Número de Copia de ADN/genética , ADN/genética , Secuenciación Completa del Genoma/normas , Adulto , ADN/sangre , ADN/química , ADN/normas , Metilación de ADN/genética , Femenino , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Mucosa Bucal/química , Polimorfismo de Nucleótido Simple/genética , Saliva/química , Análisis de Secuencia de ADN/normasRESUMEN
PurposeGenetic testing is an integral diagnostic component of pediatric medicine. Standard of care is often a time-consuming stepwise approach involving chromosomal microarray analysis and targeted gene sequencing panels, which can be costly and inconclusive. Whole-genome sequencing (WGS) provides a comprehensive testing platform that has the potential to streamline genetic assessments, but there are limited comparative data to guide its clinical use.MethodsWe prospectively recruited 103 patients from pediatric non-genetic subspecialty clinics, each with a clinical phenotype suggestive of an underlying genetic disorder, and compared the diagnostic yield and coverage of WGS with those of conventional genetic testing.ResultsWGS identified diagnostic variants in 41% of individuals, representing a significant increase over conventional testing results (24%; P = 0.01). Genes clinically sequenced in the cohort (n = 1,226) were well covered by WGS, with a median exonic coverage of 40 × ±8 × (mean ±SD). All the molecular diagnoses made by conventional methods were captured by WGS. The 18 new diagnoses made with WGS included structural and non-exonic sequence variants not detectable with whole-exome sequencing, and confirmed recent disease associations with the genes PIGG, RNU4ATAC, TRIO, and UNC13A.ConclusionWGS as a primary clinical test provided a higher diagnostic yield than conventional genetic testing in a clinically heterogeneous cohort.
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Estudios de Asociación Genética , Enfermedades Genéticas Congénitas/diagnóstico , Enfermedades Genéticas Congénitas/genética , Predisposición Genética a la Enfermedad , Pruebas Genéticas , Análisis de Secuencia de ADN , Secuenciación Completa del Genoma , Biología Computacional/métodos , Variaciones en el Número de Copia de ADN , Exoma , Femenino , Estudios de Asociación Genética/métodos , Estudios de Asociación Genética/normas , Pruebas Genéticas/métodos , Pruebas Genéticas/normas , Variación Genética , Humanos , Masculino , Anotación de Secuencia Molecular , Fenotipo , Análisis de Secuencia de ADN/métodos , Análisis de Secuencia de ADN/normas , Secuenciación del Exoma/métodos , Secuenciación del Exoma/normas , Secuenciación Completa del Genoma/métodos , Secuenciación Completa del Genoma/normasRESUMEN
Inherited photoreceptor degenerations (IPDs), a group of incurable progressive blinding diseases, are caused by mutations in more than 200 genes, but little is known about the molecular pathogenesis of photoreceptor (PR) death. Increased retinal expression of STAT3 has been observed in response to many retinal insults, including IPDs, but the role of this increase in PR death is unknown. Here, we show that the expression of Stat3 is increased in PRs of the Tg(RHO P347S) and Prph2(rds) (/+) mouse models of IPD and is activated by tyrosine phosphorylation. PR-specific deletion of Stat3 substantially accelerated PR degeneration in both mutant strains. In contrast, increased PR-specific expression of ROSA26 (R26) alleles encoding either WT STAT3 (Stat3(wt)) or the gain-of-function variant STAT3(C) (Stat3(C)) improved PR survival in both models. Moreover, PR signaling in Tg(RHO P347S) mice carrying either a R26-Stat3(wt) or R26-Stat3(C) allele demonstrated increased a-wave amplitude of the scotopic electroretinogram. Phosphorylation of STAT3 at tyrosine 705 was required for the prosurvival effect because an R26-Stat3(Y705F) allele was not protective. The prosurvival role of enhanced Stat3 activity was validated using recombinant adenoassociated virus (rAAV) vector-mediated PR Stat3 expression in Tg(RHO P347S) mice. Our findings (i) establish that the increase in endogenous PR Stat3 expression is a protective response in IPDs, (ii) suggest that therapeutic augmentation of PR Stat3 expression has potential as a common neuroprotective therapy for these disorders, and (iii) indicate that prosurvival molecules whose expression is increased in mutant PRs may have promise as novel therapies for IPDs.
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Enfermedades Genéticas Congénitas/metabolismo , Mutación , Células Fotorreceptoras de Vertebrados/metabolismo , Degeneración Retiniana/metabolismo , Factor de Transcripción STAT3/metabolismo , Animales , Supervivencia Celular/genética , Modelos Animales de Enfermedad , Regulación de la Expresión Génica/genética , Enfermedades Genéticas Congénitas/genética , Enfermedades Genéticas Congénitas/patología , Ratones , Ratones Transgénicos , Células Fotorreceptoras de Vertebrados/patología , ARN no Traducido/biosíntesis , ARN no Traducido/genética , Degeneración Retiniana/genética , Degeneración Retiniana/patología , Factor de Transcripción STAT3/genéticaRESUMEN
The cost of whole genome sequencing is dropping rapidly. There has been a great deal of enthusiasm about the potential for this technological advance to transform clinical care. Given the interest and significant investment in genomics, this seems an ideal time to consider what the evidence tells us about potential benefits and harms, particularly in the context of health care policy. The scale and pace of adoption of this powerful new technology should be driven by clinical need, clinical evidence, and a commitment to put patients at the centre of health care policy.
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Genómica/economía , Política de Salud , Secuenciación de Nucleótidos de Alto Rendimiento/economía , Análisis de Secuencia de ADN/economía , Genoma Humano , Genómica/legislación & jurisprudencia , Humanos , Opinión Pública , Estados UnidosAsunto(s)
Endoscopía Gastrointestinal , Consultoría Ética , Órdenes de Resucitación , Ética Clínica , HumanosRESUMEN
Children with rare and common diseases now undergo whole genome sequencing (WGS) in clinical and research contexts. Parents sometimes request access to their child's raw genomic data, to pursue their own analyses or for onward sharing with health professionals and researchers. These requests raise legal, ethical, and practical issues for professionals and parents alike. The advent of widespread WGS in pediatrics occurs in a context where privacy and data protection law remains focused on giving individuals control-oriented rights with respect to their personal information. Acting in their child's stead and in their best interests, parents are generally the ones who will be exercising these informational rights on behalf of the child. In this paper, we map the contours of parental authority to access their child's raw genomic data. We consider three use cases: hospital-based researchers, healthcare professionals acting in a clinical-diagnostic capacity, and "pure" academic researchers at a public institution. Our research seeks to answer two principal questions: Do parents have a right of access to their child's raw WGS data? If so, what are the limits of this right? Primarily focused on the laws of Ontario, Canada's most populous province, with a secondary focus on Canada's three other most populous provinces (Quebec, British Columbia, and Alberta) and the European Union, our principal findings include (1) parents have a general right of access to information about their children, but that the access right is more capacious in the clinical context than in the research context; (2) the right of access extends to personal data in raw form; (3) a consideration of the best interests of the child may materially limit the legal rights of parents to access data about their child; (4) the ability to exercise rights of access are transferred from parents to children when they gain decision-making capacity in both the clinical and research contexts, but with more nuance in the former. With these findings in mind, we argue that professional guidelines, which are concerned with obligations to interpret and return results, may assist in furthering a child's best interests in the context of legal access rights. We conclude by crafting recommendations for healthcare professionals in the clinical and research contexts when faced with a parental request for a child's raw genomic data.
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[This corrects the article DOI: 10.3389/fgene.2021.535340.].
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Induced pluripotent stem cells (iPSC) derived from healthy individuals are important controls for disease-modeling studies. Here we apply precision health to create a high-quality resource of control iPSCs. Footprint-free lines were reprogrammed from four volunteers of the Personal Genome Project Canada (PGPC). Multilineage-directed differentiation efficiently produced functional cortical neurons, cardiomyocytes and hepatocytes. Pilot users demonstrated versatility by generating kidney organoids, T lymphocytes, and sensory neurons. A frameshift knockout was introduced into MYBPC3 and these cardiomyocytes exhibited the expected hypertrophic phenotype. Whole-genome sequencing-based annotation of PGPC lines revealed on average 20 coding variants. Importantly, nearly all annotated PGPC and HipSci lines harbored at least one pre-existing or acquired variant with cardiac, neurological, or other disease associations. Overall, PGPC lines were efficiently differentiated by multiple users into cells from six tissues for disease modeling, and variant-preferred healthy control lines were identified for specific disease settings.
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Diferenciación Celular , Linaje de la Célula , Células Madre Pluripotentes Inducidas/citología , Células Madre Pluripotentes Inducidas/metabolismo , Sistemas CRISPR-Cas , Autorrenovación de las Células , Separación Celular , Ectodermo/citología , Ectodermo/metabolismo , Edición Génica , Humanos , Miocitos Cardíacos/citología , Miocitos Cardíacos/metabolismo , Neuronas/citología , Neuronas/metabolismo , Organoides , Fenotipo , Linfocitos T/metabolismo , Secuenciación Completa del GenomaRESUMEN
Autism spectrum disorder (ASD) is characterized by repetitive patterns of behaviour and impairments in social interactions and communication abilities. Although ASD is a heterogeneous disorder, it is a highly genetic condition for which genetic testing is routinely performed. Microarray analysis is currently the standard of care genetic test for ASD, however whole genome sequencing offers several key advantages and will likely replace microarrays as a frontline genetic test in the near future. The 2nd Consultation on Translation of Genomic Advances into Health Applications took place in the spring of 2014 to broadly explore the current and potential impacts of genomic advances in supporting personalized and family-centered care for autism and related developmental conditions. In anticipation of WGS becoming a standard of care test, we examine the policy landscape and highlight the lack of consistency among guidelines regarding what genomic information should be returned to patients and their families. We also discuss the need to create the infrastructure to share clinical WGS data with researchers in a systematic and ethically defensible manner.
Le trouble du spectre de l'autisme (TSA) est caractérisé par des comportements répétitifs et des déficiences dans les aptitudes aux interactions sociales et à la communication. Bien que le TSA soit un trouble hétérogène, c'est une affection hautement génétique pour laquelle un test génétique est régulièrement mené. L'analyse par microréseau est présentement la norme de pratique pour le TSA; cependant, le séquençage du génome entier (SGE) offre plusieurs avantages clés et remplacera probablement les microréseaux comme test génétique de première ligne dans un avenir rapproché. La 2e Consultation sur la conversion des progrès de la génomique en applications de santé a eu lieu au printemps de 2014 afin d'explorer largement les effets actuels et potentiels des progrès de la génomique pour soutenir les soins de l'autisme personnalisés et axés sur la famille, et les troubles du développement connexes. En prévision que le SGE devienne la norme de pratique des tests, nous examinons le paysage normatif et soulignons l'absence de cohérence des lignes directrices à l'égard de l'information génomique qui devrait être retournée aux patients et à leurs familles. Nous discutons également du besoin de créer l'infrastructure pour partager les données cliniques du SGE avec les chercheurs de manière systématique et éthiquement défendable.
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The standard of care for first-tier clinical investigation of the etiology of congenital malformations and neurodevelopmental disorders is chromosome microarray analysis (CMA) for copy number variations (CNVs), often followed by gene(s)-specific sequencing searching for smaller insertion-deletions (indels) and single nucleotide variant (SNV) mutations. Whole genome sequencing (WGS) has the potential to capture all classes of genetic variation in one experiment; however, the diagnostic yield for mutation detection of WGS compared to CMA, and other tests, needs to be established. In a prospective study we utilized WGS and comprehensive medical annotation to assess 100 patients referred to a paediatric genetics service and compared the diagnostic yield versus standard genetic testing. WGS identified genetic variants meeting clinical diagnostic criteria in 34% of cases, representing a 4-fold increase in diagnostic rate over CMA (8%) (p-value = 1.42e-05) alone and >2-fold increase in CMA plus targeted gene sequencing (13%) (p-value = 0.0009). WGS identified all rare clinically significant CNVs that were detected by CMA. In 26 patients, WGS revealed indel and missense mutations presenting in a dominant (63%) or a recessive (37%) manner. We found four subjects with mutations in at least two genes associated with distinct genetic disorders, including two cases harboring a pathogenic CNV and SNV. When considering medically actionable secondary findings in addition to primary WGS findings, 38% of patients would benefit from genetic counseling. Clinical implementation of WGS as a primary test will provide a higher diagnostic yield than conventional genetic testing and potentially reduce the time required to reach a genetic diagnosis.
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Expression of the Endothelin-2 (Edn2) mRNA is greatly increased in the photoreceptors (PRs) of mouse models of inherited PR degeneration (IPD). To examine the role of Edn2 in mutant PR survival, we generated Edn2(-/-) mice carrying homozygous Pde6b(rd1) alleles or the Tg(RHO P347S) transgene. In the Edn2(-/-) background, PR survival increased 110% in Pde6b(rd1/rd1) mice at post-natal (PN) day 15, and 60% in Tg(RHO P347S) mice at PN40. In contrast, PR survival was not increased in retinal explants of Pde6b(rd1/rd1) ; Edn2(-/-) mice. This finding, together with systemic abnormalities in Edn2(-/-) mice, suggested that the increased survival of mutant PRs in the Edn2(-/-) background resulted at least partly from the systemic EDN2 loss of function. To examine directly the role of EDN2 in mutant PRs, we used a scAAV5-Edn2 cDNA vector to restore Edn2 expression in Pde6b(rd1/rd1) ; Edn2(-/-) PRs and observed an 18% increase in PR survival at PN14. Importantly, PR survival was also increased after injection of scAAV5-Edn2 into Pde6b(rd1/rd1) retinas, by 31% at PN15. Together, these findings suggest that increased Edn2 expression is protective to mutant PRs. To begin to elucidate Edn2-mediated mechanisms that contribute to PR survival, we used microarray analysis and identified a cohort of 20 genes with >4-fold increased expression in Tg(RHO P347S) retinas, including Fgf2. Notably, increased expression of the FGF2 protein in Tg(RHO P347S) PRs was ablated in Tg(RHO P347S); Edn2(-/-) retinas. Our findings indicate that the increased expression of PR Edn2 increases PR survival, and suggest that the Edn2-dependent increase in PR expression of FGF2 may contribute to the augmented survival.
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Endotelina-2/metabolismo , Mutación , Células Fotorreceptoras de Vertebrados/metabolismo , Células Fotorreceptoras de Vertebrados/patología , Enfermedades de la Retina/genética , Enfermedades de la Retina/metabolismo , Animales , Hipoxia de la Célula/genética , Supervivencia Celular/genética , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 6/metabolismo , Endotelina-2/genética , Factor 2 de Crecimiento de Fibroblastos/metabolismo , Humanos , Ratones , Ratones Transgénicos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Retina/metabolismo , Retina/patología , Enfermedades de la Retina/patología , Rodopsina/genética , Transducción de Señal/genética , Regulación hacia Arriba/genéticaRESUMEN
BACKGROUND: DNA microarrays are a powerful technology that can provide a wealth of gene expression data for disease studies, drug development, and a wide scope of other investigations. Because of the large volume and inherent variability of DNA microarray data, many new statistical methods have been developed for evaluating the significance of the observed differences in gene expression. However, until now little attention has been given to the characterization of dispersion of DNA microarray data. RESULTS: Here we examine the expression data obtained from 682 Affymetrix GeneChips with 22 different types and we demonstrate that the Gaussian (normal) frequency distribution is characteristic for the variability of gene expression values. However, typically 5 to 15% of the samples deviate from normality. Furthermore, it is shown that the frequency distributions of the difference of expression in subsets of ordered, consecutive pairs of genes (consecutive samples) in pair-wise comparisons of replicate experiments are also normal. We describe a consecutive sampling method, which is employed to calculate the characteristic function approximating standard deviation and show that the standard deviation derived from the consecutive samples is equivalent to the standard deviation obtained from individual genes. Finally, we determine the boundaries of probability intervals and demonstrate that the coefficients defining the intervals are independent of sample characteristics, variability of data, laboratory conditions and type of chips. These coefficients are very closely correlated with Student's t-distribution. CONCLUSION: In this study we ascertained that the non-systematic variations possess Gaussian distribution, determined the probability intervals and demonstrated that the K(alpha) coefficients defining these intervals are invariant; these coefficients offer a convenient universal measure of dispersion of data. The fact that the K(alpha) distributions are so close to t-distribution and independent of conditions and type of arrays suggests that the quantitative data provided by Affymetrix technology give "true" representation of physical processes, involved in measurement of RNA abundance. REVIEWERS: This article was reviewed by Yoav Gilad (nominated by Doron Lancet), Sach Mukherjee (nominated by Sandrine Dudoit) and Amir Niknejad and Shmuel Friedland (nominated by Neil Smalheiser).
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Natural antisense transcripts (NATs) are a class of genes whose role in controlling gene expression is becoming more and more relevant. We describe the identification of eight novel mouse NATs associated with transcription factors (Pax6, Pax2, Six3, Six6, Otx2, Crx, Rax and Vax2) that play an important role in eye development and function. These newly identified NATs overlap with the mature processed mRNAs or with the primary unprocessed transcript of their corresponding sense genes, are predicted to represent either protein coding or non-coding RNAs and undergo extensive alternative splicing. Expression studies, by both RT-PCR and RNA in situ hybridization, demonstrate that most of these NATs, similarly to their sense counterparts, display a specific or predominant expression in the retina, particularly at postnatal stages. We found a significant reduction of the expression levels of one of these NATs, Vax2OS (Vax2 opposite strand) in a mouse mutant carrying the inactivation of Vax2, the corresponding sense gene. In addition, we overexpressed another NAT, CrxOS, in mouse adult retina using adeno-associated viral vectors and we observed a significant decrease in the expression levels of the corresponding sense gene, Crx. These results suggest that these transcripts are functionally related to their sense counterparts and may play an important role in regulating the molecular mechanisms that underlie eye development and function in both physiological and pathological conditions.