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BACKGROUND: There is limited understanding of the hypothesized association between the Ehlers-Danlos Syndromes (EDS), hypermobility and fractures in children. Despite this, EDS and hypermobility continue to be raised in the legal setting as possible causes of unexplained fractures in infants where there is a concern for physical abuse. Further understanding is needed regarding fractures in children with EDS and hypermobility. OBJECTIVE: This study assessed fracture prevalence and characteristics in children diagnosed with EDS and Generalized Joint Hypermobility (GJH). The secondary outcome was fracture prevalence in infants <1 year of age. PARTICIPANTS AND SETTING: Children aged <18 years with EDS or GJH seen in a single-center EDS clinic from April 2017 to December 2021 were included. Diagnoses were based on the 2017 international classification. Exclusion criteria were concurrent medical conditions associated with bone fragility. METHODS: This retrospective descriptive study examined variables including fracture history, fracture location, fracture type, age of sustaining fracture, and injury mechanism. Descriptive statistics were used for analysis. RESULTS: Fracture prevalence was 34.6 % (9/26, 95 % CI [16.3, 52.9]) in the EDS population and 25.4 % (15/59, 95 % CI [14.3, 36.5]) in the GJH population. No fractures occurred in infancy. Most fractures occurred in the limbs. There were no rib or skull fractures. Most fractures were the result of an identifiable injury event. CONCLUSION: In a cohort of children with formally diagnosed EDS or GJH, fractures occurred commonly in ambulatory children and generally in the limbs from identifiable events. This study does not support EDS or GJH as a cause of fractures in infancy.
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Síndrome de Ehlers-Danlos , Fracturas Óseas , Inestabilidad de la Articulación , Humanos , Síndrome de Ehlers-Danlos/epidemiología , Síndrome de Ehlers-Danlos/complicaciones , Inestabilidad de la Articulación/epidemiología , Masculino , Femenino , Prevalencia , Estudios Retrospectivos , Preescolar , Niño , Lactante , Fracturas Óseas/epidemiología , Fracturas Óseas/etiología , AdolescenteRESUMEN
Bryant-Li-Bhoj syndrome (BLBS), which became OMIM-classified in 2022 (OMIM: 619720, 619721), is caused by germline variants in the two genes that encode histone H3.3 (H3-3A/H3F3A and H3-3B/H3F3B) [1-4]. This syndrome is characterized by developmental delay/intellectual disability, craniofacial anomalies, hyper/hypotonia, and abnormal neuroimaging [1, 5]. BLBS was initially categorized as a progressive neurodegenerative syndrome caused by de novo heterozygous variants in either H3-3A or H3-3B [1-4]. Here, we analyze the data of the 58 previously published individuals along 38 unpublished, unrelated individuals. In this larger cohort of 96 people, we identify causative missense, synonymous, and stop-loss variants. We also expand upon the phenotypic characterization by elaborating on the neurodevelopmental component of BLBS. Notably, phenotypic heterogeneity was present even amongst individuals harboring the same variant. To explore the complex phenotypic variation in this expanded cohort, the relationships between syndromic phenotypes with three variables of interest were interrogated: sex, gene containing the causative variant, and variant location in the H3.3 protein. While specific genotype-phenotype correlations have not been conclusively delineated, the results presented here suggest that the location of the variants within the H3.3 protein and the affected gene (H3-3A or H3-3B) contribute more to the severity of distinct phenotypes than sex. Since these variables do not account for all BLBS phenotypic variability, these findings suggest that additional factors may play a role in modifying the phenotypes of affected individuals. Histones are poised at the interface of genetics and epigenetics, highlighting the potential role for gene-environment interactions and the importance of future research.
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Histonas , Fenotipo , Humanos , Masculino , Femenino , Histonas/genética , Niño , Enfermedades Neurodegenerativas/genética , Enfermedades Neurodegenerativas/patología , Trastornos del Neurodesarrollo/genética , Trastornos del Neurodesarrollo/patología , Preescolar , Adolescente , Adulto , Discapacidad Intelectual/genética , Discapacidad Intelectual/patologíaRESUMEN
Canonical splice site variants (CSSVs) are often presumed to cause loss-of-function (LoF) and are assigned very strong evidence of pathogenicity (according to American College of Medical Genetics/Association for Molecular Pathology criterion PVS1). The exact nature and predictability of splicing effects of unselected rare CSSVs in blood-expressed genes are poorly understood. We identified 168 rare CSSVs in blood-expressed genes in 112 individuals using genome sequencing, and studied their impact on splicing using RNA sequencing (RNA-seq). There was no evidence of a frameshift, nor of reduced expression consistent with nonsense-mediated decay, for 25.6% of CSSVs: 17.9% had wildtype splicing only and normal junction depths, 3.6% resulted in cryptic splice site usage and in-frame insertions or deletions, 3.6% resulted in full exon skipping (in frame), and 0.6% resulted in full intron inclusion (in frame). Blind to these RNA-seq data, we attempted to predict the precise impact of CSSVs by applying in silico tools and the ClinGen Sequence Variant Interpretation Working Group 2018 guidelines for applying PVS1 criterion. The predicted impact on splicing using (1) SpliceAI, (2) MaxEntScan, and (3) AutoPVS1, an automatic classification tool for PVS1 interpretation of null variants that utilizes Ensembl Variant Effect Predictor and MaxEntScan, was concordant with RNA-seq analyses for 65%, 63%, and 61% of CSSVs, respectively. In summary, approximately one in four rare CSSVs did not show evidence for LoF based on analysis of RNA-seq data. Predictions from in silico methods were often discordant with findings from RNA-seq. More caution may be warranted in applying PVS1-level evidence to CSSVs in the absence of functional data.
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Simulación por Computador , Sitios de Empalme de ARN , Empalme del ARN , Humanos , Sitios de Empalme de ARN/genética , Empalme del ARN/genética , Biología Computacional/métodos , Exones/genética , Variación Genética/genéticaRESUMEN
OBJECTIVE: The objective of this study was to assess the prevalence of genetic variants associated with hearing loss in a large cohort of children in Canada using high throughput next generation sequencing (NGS). METHODS: A total of 485 children with hearing loss underwent NGS testing with an 80 gene panel of syndromic and non-syndromic variants known to be associated with hearing loss. Genetic variants were classified as pathogenic, likely pathogenic, likely benign, benign, or variants of uncertain significance (VUS), according to the American College of Medical Genetics and Genomics guidelines. RESULTS: Across the 80 genes tested, 923 variants, predominantly in 28 genes, were identified in 324 children. Pathogenic variants occurred in 19/80 (23.8%) of the hearing loss related genes tested and confirmed the etiology of hearing loss in 73/485 (15.1%) of children. GJB2 was the most prevalent gene, affecting 28/73 (38.4%) children with confirmed genetic hearing loss in our cohort. Most identified variants (748/923, 81.0%, in 76/80 genes) were of uncertain significance. CONCLUSION: Genetic testing using NGS identified the etiology in approximately 15% of childhood hearing loss in a Canadian cohort which is lower than what is typically reported. GJB2 was the most common genetic cause of hearing loss. VUS are commonly identified, presenting clinical challenges for counseling. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:3832-3838, 2024.
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Pruebas Genéticas , Pérdida Auditiva , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Canadá/epidemiología , Niño , Masculino , Femenino , Preescolar , Prevalencia , Pérdida Auditiva/genética , Pérdida Auditiva/epidemiología , Lactante , Adolescente , Estudios de Cohortes , Variación Genética/genética , Conexina 26/genética , Predisposición Genética a la EnfermedadRESUMEN
Neuronal ceroid lipofuscinosis (NCL), type 6 (CLN6) is a neurodegenerative disorder associated with progressive neurodegeneration leading to dementia, seizures, and retinopathy. CLN6 encodes a resident-ER protein involved in trafficking lysosomal proteins to the Golgi. CLN6p deficiency results in lysosomal dysfunction and deposition of storage material comprised of Nile Red + lipids/proteolipids that include subunit C of the mitochondrial ATP synthase (SUBC). White matter involvement has been recently noted in several CLN6 animal models and several CLN6 subjects had neuroimaging was consistent with leukodystrophy. CLN6 patient-derived induced pluripotent stem cells (IPSCs) were generated from several of these subjects. IPSCs were differentiated into oligodendroglia or neurons using well-established small-molecule protocols. A doxycycline-inducible transgenic system expressing neurogenin-2 (the I3N-system) was also used to generate clonal IPSC-lines (I3N-IPSCs) that could be rapidly differentiated into neurons (I3N-neurons). All CLN6 IPSC-derived neural cell lines developed significant storage material, CLN6-I3N-neuron lines revealed significant Nile Red + and SUBC + storage within three and seven days of neuronal induction, respectively. CLN6-I3N-neurons had decreased tripeptidyl peptidase-1 activity, increased Golgi area, along with increased LAMP1 + in cell bodies and neurites. SUBC + signal co-localized with LAMP1 + signal. Bulk-transcriptomic evaluation of control- and CLN6-I3N-neurons identified >1300 differentially-expressed genes (DEGs) with Gene Ontogeny (GO) Enrichment and Canonical Pathway Analyses having significant changes in lysosomal, axonal, synaptic, and neuronal-apoptotic gene pathways. These findings indicate that CLN6-IPSCs and CLN6-I3N-IPSCs are appropriate cellular models for this disorder. These I3N-neuron models may be particularly valuable for developing therapeutic interventions with high-throughput drug screening assays and/or gene therapy.
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PURPOSE: To evaluate the diagnostic utility of publicly funded clinical exome sequencing (ES) for patients with suspected rare genetic diseases. METHODS: We prospectively enrolled 297 probands who met eligibility criteria and received ES across 5 sites in Ontario, Canada, and extracted data from medical records and clinician surveys. Using the Fryback and Thornbury Efficacy Framework, we assessed diagnostic accuracy by examining laboratory interpretation of results and assessed diagnostic thinking by examining the clinical interpretation of results and whether clinical-molecular diagnoses would have been achieved via alternative hypothetical molecular tests. RESULTS: Laboratories reported 105 molecular diagnoses and 165 uncertain results in known and novel genes. Of these, clinicians interpreted 102 of 105 (97%) molecular diagnoses and 6 of 165 (4%) uncertain results as clinical-molecular diagnoses. The 108 clinical-molecular diagnoses were in 104 families (35% diagnostic yield). Each eligibility criteria resulted in diagnostic yields of 30% to 40%, and higher yields were achieved when >2 eligibility criteria were met (up to 45%). Hypothetical tests would have identified 61% of clinical-molecular diagnoses. CONCLUSION: We demonstrate robustness in eligibility criteria and high clinical validity of laboratory results from ES testing. The importance of ES was highlighted by the potential 40% of patients that would have gone undiagnosed without this test.
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Exoma , Enfermedades Raras , Humanos , Estudios Prospectivos , Secuenciación del Exoma , Enfermedades Raras/diagnóstico , Enfermedades Raras/genética , Pruebas Genéticas/métodos , OntarioRESUMEN
Ferritin, the iron-storage protein, is composed of light- and heavy-chain subunits, encoded by FTL and FTH1, respectively. Heterozygous variants in FTL cause hereditary neuroferritinopathy, a type of neurodegeneration with brain iron accumulation (NBIA). Variants in FTH1 have not been previously associated with neurologic disease. We describe the clinical, neuroimaging, and neuropathology findings of five unrelated pediatric patients with de novo heterozygous FTH1 variants. Children presented with developmental delay, epilepsy, and progressive neurologic decline. Nonsense FTH1 variants were identified using whole-exome sequencing, with a recurrent variant (p.Phe171∗) identified in four unrelated individuals. Neuroimaging revealed diffuse volume loss, features of pontocerebellar hypoplasia, and iron accumulation in the basal ganglia. Neuropathology demonstrated widespread ferritin inclusions in the brain. Patient-derived fibroblasts were assayed for ferritin expression, susceptibility to iron accumulation, and oxidative stress. Variant FTH1 mRNA transcripts escape nonsense-mediated decay (NMD), and fibroblasts show elevated ferritin protein levels, markers of oxidative stress, and increased susceptibility to iron accumulation. C-terminal variants in FTH1 truncate ferritin's E helix, altering the 4-fold symmetric pores of the heteropolymer, and likely diminish iron-storage capacity. FTH1 pathogenic variants appear to act by a dominant, toxic gain-of-function mechanism. The data support the conclusion that truncating variants in the last exon of FTH1 cause a disorder in the spectrum of NBIA. Targeted knockdown of mutant FTH1 transcript with antisense oligonucleotides rescues cellular phenotypes and suggests a potential therapeutic strategy for this pediatric neurodegenerative disorder.
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Apoferritinas , Trastornos del Metabolismo del Hierro , Distrofias Neuroaxonales , Humanos , Niño , Apoferritinas/genética , Trastornos del Metabolismo del Hierro/genética , Hierro/metabolismo , Ferritinas/genética , Oxidorreductasas/metabolismoRESUMEN
PURPOSE: Although costly, genome-wide sequencing (GWS) detects an extensive range of variants, enhancing our ability to diagnose and assess risk for an increasing number of diseases. In addition to detecting variants related to the indication for testing, GWS can detect secondary variants in BRCA1, BRCA2, and other genes for which early intervention may improve health. As the list of secondary findings grows, there is increased demand for surveillance and management by multiple specialists, adding pressure to constrained health care budgets. Secondary finding testing is actively debated because some consider it opportunistic screening for future health risks that may not manifest. Given the economic implications of secondary finding testing and follow-up and its unproven clinical utility, the objective is to assess the incremental cost-effectiveness of secondary finding ascertainment per case detected and per unit of improved clinical utility in families of children with unexplained suspected genetic conditions undergoing clinical GWS. METHODS: Those undergoing trio genome or exome sequencing are eligible for the study. Positive secondary finding index cases will be matched to negative controls (1:2) based on age group, primary result(s) type, and clinical indication. During the 2-year study, 71 cases and 142 matched controls are expected. Health service use will be collected in patients and 1 adult family member every 6 months. The per-child and per-dyad total cost will be determined by multiplying use of each resource by a corresponding unit price and summing all cost items. Costs will be estimated from the public and societal payer perspectives. The mean cost per child and per dyad for secondary finding-positive and secondary finding-negative groups will be compared statistically. If important demographic differences are observed between groups, ordinary least-squares regression, log transformation, or other nonparametric technique will be used to compare adjusted mean costs. The ratio of the difference in mean cost to the secondary finding yield will be used to estimate incremental cost-effectiveness. In secondary analyses, effectiveness will be estimated using the number of clinical management changes due to secondary findings or the Clinician-Reported Genetic Testing Utility Index (C-GUIDE) score, a validated measure of clinical utility. Sensitivity analysis will be undertaken to assess the robustness of the findings to variation in key parameters. IMPLICATIONS: This study generates key evidence to inform clinical practice and funding allocation related to secondary finding testing. The inclusion of family members and a new measure of clinical utility represent important advancements in economic evaluation in genomics.
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ERI1 is a 3'-to-5' exoribonuclease involved in RNA metabolic pathways including 5.8S rRNA processing and turnover of histone mRNAs. Its biological and medical significance remain unclear. Here, we uncover a phenotypic dichotomy associated with bi-allelic ERI1 variants by reporting eight affected individuals from seven unrelated families. A severe spondyloepimetaphyseal dysplasia (SEMD) was identified in five affected individuals with missense variants but not in those with bi-allelic null variants, who showed mild intellectual disability and digital anomalies. The ERI1 missense variants cause a loss of the exoribonuclease activity, leading to defective trimming of the 5.8S rRNA 3' end and a decreased degradation of replication-dependent histone mRNAs. Affected-individual-derived induced pluripotent stem cells (iPSCs) showed impaired in vitro chondrogenesis with downregulation of genes regulating skeletal patterning. Our study establishes an entity previously unreported in OMIM and provides a model showing a more severe effect of missense alleles than null alleles within recessive genotypes, suggesting a key role of ERI1-mediated RNA metabolism in human skeletal patterning and chondrogenesis.
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Exorribonucleasas , Histonas , Humanos , Exorribonucleasas/genética , Histonas/genética , Mutación Missense/genética , ARN Ribosómico 5.8S , ARN , ARN Mensajero/genéticaRESUMEN
PURPOSE: Bone morphogenic proteins (BMPs) regulate gene expression that is related to many critical developmental processes, including osteogenesis for which they are named. In addition, BMP2 is widely expressed in cells of mesenchymal origin, including bone, cartilage, skeletal and cardiac muscle, and adipose tissue. It also participates in neurodevelopment by inducing differentiation of neural stem cells. In humans, BMP2 variants result in a multiple congenital anomaly syndrome through a haploinsufficiency mechanism. We sought to expand the phenotypic spectrum and highlight phenotypes of patients harboring monoallelic missense variants in BMP2. METHODS: We used retrospective chart review to examine phenotypes from an international cohort of 18 individuals and compared these with published cases. Patient-derived missense variants were modeled in zebrafish to examine their effect on the ability of bmp2b to promote embryonic ventralization. RESULTS: The presented cases recapitulated existing descriptions of BMP2-related disorders, including craniofacial, cardiac, and skeletal anomalies and exhibit a wide phenotypic spectrum. We also identified patients with neural tube defects, structural brain anomalies, and endocrinopathies. Missense variants modeled in zebrafish resulted in loss of protein function. CONCLUSION: We use this expansion of reported phenotypes to suggest multidisciplinary medical monitoring and management of patients with BMP2-related skeletal dysplasia spectrum.
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Osteocondrodisplasias , Pez Cebra , Animales , Humanos , Pez Cebra/genética , Estudios Retrospectivos , Diferenciación Celular , Osteogénesis/genética , Proteínas Morfogenéticas Óseas , Proteína Morfogenética Ósea 2/genéticaRESUMEN
Genome sequencing (GS) is a powerful test for the diagnosis of rare genetic disorders. Although GS can enumerate most non-coding variation, determining which non-coding variants are disease-causing is challenging. RNA sequencing (RNA-seq) has emerged as an important tool to help address this issue, but its diagnostic utility remains understudied, and the added value of a trio design is unknown. We performed GS plus RNA-seq from blood using an automated clinical-grade high-throughput platform on 97 individuals from 39 families where the proband was a child with unexplained medical complexity. RNA-seq was an effective adjunct test when paired with GS. It enabled clarification of putative splice variants in three families, but it did not reveal variants not already identified by GS analysis. Trio RNA-seq decreased the number of candidates requiring manual review when filtering for de novo dominant disease-causing variants, allowing for the exclusion of 16% of gene-expression outliers and 27% of allele-specific-expression outliers. However, clear diagnostic benefit from the trio design was not observed. Blood-based RNA-seq can facilitate genome analysis in children with suspected undiagnosed genetic disease. In contrast to DNA sequencing, the clinical advantages of a trio RNA-seq design may be more limited.
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Familia , Enfermedades Raras , Humanos , Niño , Secuencia de Bases , Análisis de Secuencia de ADN , Secuenciación del Exoma , Enfermedades Raras/genética , Análisis de Secuencia de ARNRESUMEN
Ferritin, the iron storage protein, is composed of light and heavy chain subunits, encoded by FTL and FTH1 , respectively. Heterozygous variants in FTL cause hereditary neuroferritinopathy, a type of neurodegeneration with brain iron accumulation (NBIA). Variants in FTH1 have not been previously associated with neurologic disease. We describe the clinical, neuroimaging, and neuropathology findings of five unrelated pediatric patients with de novo heterozygous FTH1 variants. Children presented with developmental delay, epilepsy, and progressive neurologic decline. Nonsense FTH1 variants were identified using whole exome sequencing, with a recurrent de novo variant (p.F171*) identified in three unrelated individuals. Neuroimaging revealed diffuse volume loss, features of pontocerebellar hypoplasia and iron accumulation in the basal ganglia. Neuropathology demonstrated widespread ferritin inclusions in the brain. Patient-derived fibroblasts were assayed for ferritin expression, susceptibility to iron accumulation, and oxidative stress. Variant FTH1 mRNA transcripts escape nonsense-mediated decay (NMD), and fibroblasts show elevated ferritin protein levels, markers of oxidative stress, and increased susceptibility to iron accumulation. C-terminus variants in FTH1 truncate ferritin's E-helix, altering the four-fold symmetric pores of the heteropolymer and likely diminish iron-storage capacity. FTH1 pathogenic variants appear to act by a dominant, toxic gain-of-function mechanism. The data support the conclusion that truncating variants in the last exon of FTH1 cause a novel disorder in the spectrum of NBIA. Targeted knock-down of mutant FTH1 transcript with antisense oligonucleotides rescues cellular phenotypes and suggests a potential therapeutic strategy for this novel pediatric neurodegenerative disorder.
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Congenital ichthyosis is a genodermatosis characterized by abnormal epidermal differentiation. The neonatal period is critical for patients with ichthyosis because of the risk for significant comorbidities and associated mortality, with most complications resulting from impaired barrier function. Early recognition can significantly alter the clinical course of this rare disease. Here we present a neonate with ichthyosis, leukocyte vacuoles, alopecia, and sclerosing cholangitis syndrome (ILVASC), a rare inherited disease, to highlight how an interdisciplinary approach led to prompt assessment, confirmation of a genetic diagnosis and management of potential complications.
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Ictiosis Lamelar , Ictiosis , Trastornos Leucocíticos , Recién Nacido , Humanos , Alopecia/genética , Ictiosis/diagnóstico , Ictiosis/genética , Trastornos Leucocíticos/genética , Síndrome , Diagnóstico PrecozRESUMEN
Missense and truncating variants in the X-chromosome-linked CLCN4 gene, resulting in reduced or complete loss-of-function (LOF) of the encoded chloride/proton exchanger ClC-4, were recently demonstrated to cause a neurocognitive phenotype in both males and females. Through international clinical matchmaking and interrogation of public variant databases we assembled a database of 90 rare CLCN4 missense variants in 90 families: 41 unique and 18 recurrent variants in 49 families. For 43 families, including 22 males and 33 females, we collated detailed clinical and segregation data. To confirm causality of variants and to obtain insight into disease mechanisms, we investigated the effect on electrophysiological properties of 59 of the variants in Xenopus oocytes using extended voltage and pH ranges. Detailed analyses revealed new pathophysiological mechanisms: 25% (15/59) of variants demonstrated LOF, characterized by a "shift" of the voltage-dependent activation to more positive voltages, and nine variants resulted in a toxic gain-of-function, associated with a disrupted gate allowing inward transport at negative voltages. Functional results were not always in line with in silico pathogenicity scores, highlighting the complexity of pathogenicity assessment for accurate genetic counselling. The complex neurocognitive and psychiatric manifestations of this condition, and hitherto under-recognized impacts on growth, gastrointestinal function, and motor control are discussed. Including published cases, we summarize features in 122 individuals from 67 families with CLCN4-related neurodevelopmental condition and suggest future research directions with the aim of improving the integrated care for individuals with this diagnosis.
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Trastornos del Neurodesarrollo , Masculino , Femenino , Humanos , Trastornos del Neurodesarrollo/genética , Mutación Missense , Genes Ligados a X , Fenotipo , Canales de Cloruro/genéticaRESUMEN
We examined the utility of clinical and research processes in the reanalysis of publicly-funded clinical exome sequencing data in Ontario, Canada. In partnership with eight sites, we recruited 287 families with suspected rare genetic diseases tested between 2014 and 2020. Data from seven laboratories was reanalyzed with the referring clinicians. Reanalysis of clinically relevant genes identified diagnoses in 4% (13/287); four were missed by clinical testing. Translational research methods, including analysis of novel candidate genes, identified candidates in 21% (61/287). Of these, 24 families have additional evidence through data sharing to support likely diagnoses (8% of cohort). This study indicates few diagnoses are missed by clinical laboratories, the incremental gain from reanalysis of clinically-relevant genes is modest, and the highest yield comes from validation of novel disease-gene associations. Future implementation of translational research methods, including continued reporting of compelling genes of uncertain significance by clinical laboratories, should be considered to maximize diagnoses.
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Pruebas Genéticas , Humanos , Pruebas Genéticas/métodos , Ontario/epidemiología , Secuenciación del ExomaRESUMEN
PURA syndrome is caused by heterozygous de novo pathogenic variants in PURA. It is characterized by moderate to severe neurodevelopmental disability with a wide clinical spectrum and an evolving phenotype. We present two individuals with genetically confirmed PURA syndrome who had severe neonatal signs and symptoms and a novel phenotype suggestive of neuromuscular junction pathology. We demonstrate that PURA syndrome shares features consistent with a congenital myasthenic syndrome; we thus recommend electrodiagnostic study in neonates and infants with PURA syndrome, and consideration of salbutamol as a therapeutic option.
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Epilepsia , Discapacidad Intelectual , Síndromes Miasténicos Congénitos , Humanos , Discapacidad Intelectual/genética , Síndromes Miasténicos Congénitos/diagnóstico , Síndromes Miasténicos Congénitos/genética , Unión Neuromuscular , Fenotipo , Proteínas de Unión al ADN/genética , Factores de Transcripción/genéticaRESUMEN
BACKGROUND: Genome-wide sequencing has emerged as a promising strategy for the timely diagnosis of rare diseases, but it is not yet available as a clinical test performed in Canadian diagnostic laboratories. We describe the protocol for evaluating a 2-year pilot project, Genome-wide Sequencing Ontario, to offer high-quality clinical genome-wide sequencing in Ontario, Canada. METHODS: The Genome-wide Sequencing Ontario protocol was codesigned by the Ontario Ministry of Health, the Hospital for Sick Children in Toronto and the Children's Hospital of Eastern Ontario in Ottawa. Enrolment of a prospective cohort of patients began on Apr. 1, 2021. Eligible cases with blood samples available for the index case and both parents (i.e., trios) are randomized to receive exome sequencing or genome sequencing. We will collect patient-level data and ascertain costs associated with the laboratory workflow for exome sequencing and genome sequencing. We will compare point estimates for the diagnostic utility and timeliness of exome sequencing and genome sequencing, and we will determine an incremental cost-effectiveness ratio (expressed as the incremental cost of genome sequencing versus exome sequencing per additional patient with a causal variant detected). INTERPRETATION: Findings from this work will provide robust evidence for the diagnostic utility, cost-effectiveness and timeliness of exome sequencing and genome sequencing, and will be disseminated via academic publications and policy briefs. Findings will inform provincial and cross-provincial policy related to the long-term organization, delivery and reimbursement of clinical-grade genome diagnostics for rare disease.
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Enfermedades Raras , Niño , Humanos , Ontario/epidemiología , Proyectos Piloto , Estudios Prospectivos , Ensayos Clínicos Controlados Aleatorios como Asunto , Enfermedades Raras/diagnóstico , Enfermedades Raras/genética , Secuenciación del ExomaRESUMEN
Ehlers-Danlos syndrome (EDS) is a heterogeneous group of connective tissue disorders characterized by hyperextensible skin, hypermobile joints, easy bruisability, and fragility of the connective tissues. The diagnosis is based on clinical assessment and phenotype-guided genetic testing. Most EDS subtypes can be confirmed by genetic testing except for hypermobile EDS. This study explored the utility of applying the 2017 EDS classification criteria and molecular genetic testing in establishing an EDS diagnosis in children. In this retrospective study, we reviewed 72 patients referred to a tertiary care center for evaluation of EDS who underwent one or more forms of genetic testing. Eighteen patients (18/72, 25%) met the clinical criteria for one of the EDS subtypes and of these, 15 (15/18, 83%) were confirmed molecularly. Fifty-four patients (54/72, 75%) had features that overlapped EDS and other syndromes associated with joint hypermobility but did not fully meet clinical criteria. Twelve of them (12/54, 22%) were later shown to have a positive molecular genetic diagnosis of EDS. Different molecular genetic tests were performed on the cohort of 72 patients (EDS panel, n = 44; microarray, n = 25; whole exome sequencing [WES], n = 9; single gene sequencing, n = 3; familial variant testing, n = 10; other genetic panels n = 3). EDS panel was completed in 44 patients (61%), and a molecular diagnosis was confirmed in nine of the patients who satisfied criteria for one of the EDS subtypes (9/12, 75%) and in nine of the patients who did not fully meet criteria (9/32, 28%). We observed a correlation between generalized joint hypermobility, poor healing, easy bruising, atrophic scars, skin hyperextensibility, and developmental dysplasia of the hip with a positive molecular result. This study provides guidance for the use of molecular genetic testing in combination with the 2017 clinical diagnostic criteria in children presenting with EDS characteristics.
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Enfermedades del Tejido Conjuntivo , Síndrome de Ehlers-Danlos , Inestabilidad de la Articulación , Anomalías Cutáneas , Enfermedades del Tejido Conjuntivo/genética , Síndrome de Ehlers-Danlos/diagnóstico , Síndrome de Ehlers-Danlos/genética , Humanos , Inestabilidad de la Articulación/diagnóstico , Inestabilidad de la Articulación/genética , Biología Molecular , Estudios RetrospectivosRESUMEN
Kabuki syndrome (KS) is a neurodevelopmental disorder characterized by hypotonia, intellectual disability, skeletal anomalies, and postnatal growth restriction. The characteristic facial appearance is not pathognomonic for KS as several other conditions demonstrate overlapping features. For 20-30% of children with a clinical diagnosis of KS, no causal variant is identified by conventional genetic testing of the two associated genes, KMT2D and KDM6A. Here, we describe two cases of suspected KS that met clinical diagnostic criteria and had a high gestalt match on the artificial intelligence platform Face2Gene. Although initial KS testing was negative, genome-wide DNA methylation (DNAm) was instrumental in guiding genome sequencing workflow to establish definitive molecular diagnoses. In one case, a positive DNAm signature for KMT2D led to the identification of a cryptic variant in KDM6A by genome sequencing; for the other case, a DNAm signature different from KS led to the detection of another diagnosis in the KS differential, CDK13-related disorder. This approach illustrates the clinical utility of DNAm signatures in the diagnostic workflow for the genome analyst or clinical geneticist-especially for disorders with overlapping clinical phenotypes.