Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 14 de 14
Filtrar
Filtros adicionais











Intervalo de ano
1.
Eur J Hum Genet ; 27(8): 1267-1273, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31024060

RESUMO

We establish autosomal recessive DES variants p.(Leu190Pro) and a deep intronic splice variant causing inclusion of a frameshift-inducing artificial exon/intronic fragment, as the likely cause of myopathy with cardiac involvement in female siblings. Both sisters presented in their twenties with slowly progressive limb girdle weakness, severe systolic dysfunction, and progressive, severe respiratory weakness. Desmin is an intermediate filament protein typically associated with autosomal dominant myofibrillar myopathy with cardiac involvement. However a few rare cases of autosomal recessive desminopathy are reported. In this family, a paternal missense p.(Leu190Pro) variant was viewed unlikely to be causative of autosomal dominant desminopathy, as the father and brothers carrying this variant were clinically unaffected. Clinical fit with a DES-related myopathy encouraged closer scrutiny of all DES variants, identifying a maternal deep intronic variant within intron-7, predicted to create a cryptic splice site, which segregated with disease. RNA sequencing and studies of muscle cDNA confirmed the deep intronic variant caused aberrant splicing of an artificial exon/intronic fragment into maternal DES mRNA transcripts, encoding a premature termination codon, and potently activating nonsense-mediate decay (92% paternal DES transcripts, 8% maternal). Western blot showed 60-75% reduction in desmin levels, likely comprised only of missense p.(Leu190Pro) desmin. Biopsy showed fibre size variation with increased central nuclei. Electron microscopy showed extensive myofibrillar disarray, duplication of the basal lamina, but no inclusions or aggregates. This study expands the phenotypic spectrum of recessive DES cardio/myopathy, and emphasizes the continuing importance of muscle biopsy for functional genomics pursuit of 'tricky' variants in neuromuscular conditions.

2.
JCI Insight ; 4(6)2019 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-30895940

RESUMO

The clinical application of advanced next-generation sequencing technologies is increasingly uncovering novel classes of mutations that may serve as potential targets for precision medicine therapeutics. Here, we show that a deep intronic splice defect in the COL6A1 gene, originally discovered by applying muscle RNA sequencing in patients with clinical findings of collagen VI-related dystrophy (COL6-RD), inserts an in-frame pseudoexon into COL6A1 mRNA, encodes a mutant collagen α1(VI) protein that exerts a dominant-negative effect on collagen VI matrix assembly, and provides a unique opportunity for splice-correction approaches aimed at restoring normal gene expression. Using splice-modulating antisense oligomers, we efficiently skipped the pseudoexon in patient-derived fibroblast cultures and restored a wild-type matrix. Similarly, we used CRISPR/Cas9 to precisely delete an intronic sequence containing the pseudoexon and efficiently abolish its inclusion while preserving wild-type splicing. Considering that this splice defect is emerging as one of the single most frequent mutations in COL6-RD, the design of specific and effective splice-correction therapies offers a promising path for clinical translation.

4.
Genome Res ; 29(1): 53-63, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30552105

RESUMO

The evolutionary history of a gene helps predict its function and relationship to phenotypic traits. Although sequence conservation is commonly used to decipher gene function and assess medical relevance, methods for functional inference from comparative expression data are lacking. Here, we use RNA-seq across seven tissues from 17 mammalian species to show that expression evolution across mammals is accurately modeled by the Ornstein-Uhlenbeck process, a commonly proposed model of continuous trait evolution. We apply this model to identify expression pathways under neutral, stabilizing, and directional selection. We further demonstrate novel applications of this model to quantify the extent of stabilizing selection on a gene's expression, parameterize the distribution of each gene's optimal expression level, and detect deleterious expression levels in expression data from individual patients. Our work provides a statistical framework for interpreting expression data across species and in disease.


Assuntos
Evolução Molecular , Regulação da Expressão Gênica/fisiologia , Modelos Genéticos , Animais , Cães , Coelhos
5.
Mol Genet Metab ; 126(1): 77-82, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30558828

RESUMO

BACKGROUND: In almost half of patients with acute liver failure the cause is unknown, making targeted treatment and decisions about liver transplantation a challenge. Monogenic disorders may contribute to a significant proportion of these undiagnosed patients, and so the incorporation of technologies such as next generation sequencing (NGS) in the clinic could aid in providing a definitive diagnosis. However, this technology may present a major challenge in interpretation of sequence variants, particularly those in non-coding regions. RESULTS: In this report we describe a case of Infantile liver failure syndrome 2 (ILFS2; MIM 616483) due to novel bi-allelic variants in the NBAS gene. A missense variant NM_015909.3(NBAS):c.2617C > T, NP_056993.2(NBAS):p.(Arg873Trp) was identified by whole genome sequencing (WGS). By combining WGS and reverse transcription-polymerase chain reaction (RT-PCR) we were able to identify a novel deep intronic variant, NM_015909.3(NBAS):c.2423 + 404G > C, leading to the inclusion of a pseudo-exon. This mechanism has not been described previously in this syndrome. CONCLUSIONS: This study highlights the utility of analyzing NGS data in conjunction with investigating complementary DNA (cDNA) using techniques such as RT-PCR for detection of variants that otherwise would be likely to be missed in common NGS bioinformatic analysis pipelines. Combining these approaches, particularly when the phenotype match is strong, could lead to an increase in the diagnostic yield in acute liver failure and thus aid in targeted treatment, accurate genetic counseling and restoration of reproductive confidence.


Assuntos
Variação Genética , Íntrons , Falência Hepática Aguda/genética , Proteínas de Neoplasias/genética , Alelos , Criança , Biologia Computacional , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Falência Hepática Aguda/diagnóstico , Transplante de Fígado , Mutação , Fenótipo , Sequenciamento Completo do Genoma
6.
Am J Hum Genet ; 2018 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-30503522

RESUMO

Diamond-Blackfan anemia (DBA) is a rare bone marrow failure disorder that affects 7 out of 1,000,000 live births and has been associated with mutations in components of the ribosome. In order to characterize the genetic landscape of this heterogeneous disorder, we recruited a cohort of 472 individuals with a clinical diagnosis of DBA and performed whole-exome sequencing (WES). We identified relevant rare and predicted damaging mutations for 78% of individuals. The majority of mutations were singletons, absent from population databases, predicted to cause loss of function, and located in 1 of 19 previously reported ribosomal protein (RP)-encoding genes. Using exon coverage estimates, we identified and validated 31 deletions in RP genes. We also observed an enrichment for extended splice site mutations and validated their diverse effects using RNA sequencing in cell lines obtained from individuals with DBA. Leveraging the size of our cohort, we observed robust genotype-phenotype associations with congenital abnormalities and treatment outcomes. We further identified rare mutations in seven previously unreported RP genes that may cause DBA, as well as several distinct disorders that appear to phenocopy DBA, including nine individuals with biallelic CECR1 mutations that result in deficiency of ADA2. However, no new genes were identified at exome-wide significance, suggesting that there are no unidentified genes containing mutations readily identified by WES that explain >5% of DBA-affected case subjects. Overall, this report should inform not only clinical practice for DBA-affected individuals, but also the design and analysis of rare variant studies for heterogeneous Mendelian disorders.

8.
Hum Mutat ; 39(3): 383-388, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29266598

RESUMO

A male neonate presented with severe weakness, hypotonia, contractures and congenital scoliosis. Skeletal muscle specimens showed marked atrophy and degeneration of fast fibers with striking nemaline rods and hypertrophy of slow fibers that were ultrastructurally normal. A neuromuscular gene panel identified a homozygous essential splice variant in TNNT3 (chr11:1956150G > A, NM_006757.3:c.681+1G > A). TNNT3 encodes skeletal troponin-Tfast and is associated with autosomal dominant distal arthrogryposis. TNNT3 has not previously been associated with nemaline myopathy (NM), a rare congenital myopathy linked to defects in proteins associated with thin filament structure and regulation. cDNA studies confirmed pathogenic consequences of the splice variant, eliciting exon-skipping and intron retention events leading to a frameshift. Western blot showed deficiency of troponin-Tfast protein with secondary loss of troponin-Ifast . We establish a homozygous splice variant in TNNT3 as the likely cause of severe congenital NM with distal arthrogryposis, characterized by specific involvement of Type-2 fibers and deficiency of troponin-Tfast .

9.
Nature ; 550(7675): 244-248, 2017 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-29022598

RESUMO

X chromosome inactivation (XCI) silences transcription from one of the two X chromosomes in female mammalian cells to balance expression dosage between XX females and XY males. XCI is, however, incomplete in humans: up to one-third of X-chromosomal genes are expressed from both the active and inactive X chromosomes (Xa and Xi, respectively) in female cells, with the degree of 'escape' from inactivation varying between genes and individuals. The extent to which XCI is shared between cells and tissues remains poorly characterized, as does the degree to which incomplete XCI manifests as detectable sex differences in gene expression and phenotypic traits. Here we describe a systematic survey of XCI, integrating over 5,500 transcriptomes from 449 individuals spanning 29 tissues from GTEx (v6p release) and 940 single-cell transcriptomes, combined with genomic sequence data. We show that XCI at 683 X-chromosomal genes is generally uniform across human tissues, but identify examples of heterogeneity between tissues, individuals and cells. We show that incomplete XCI affects at least 23% of X-chromosomal genes, identify seven genes that escape XCI with support from multiple lines of evidence and demonstrate that escape from XCI results in sex biases in gene expression, establishing incomplete XCI as a mechanism that is likely to introduce phenotypic diversity. Overall, this updated catalogue of XCI across human tissues helps to increase our understanding of the extent and impact of the incompleteness in the maintenance of XCI.


Assuntos
Especificidade de Órgãos/genética , Análise de Célula Única , Inativação do Cromossomo X/genética , Cromossomos Humanos X/genética , Feminino , Genes Ligados ao Cromossomo X/genética , Genoma Humano/genética , Genômica , Humanos , Masculino , Fenótipo , Análise de Sequência de RNA , Transcriptoma/genética
10.
Sci Transl Med ; 9(386)2017 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-28424332

RESUMO

Exome and whole-genome sequencing are becoming increasingly routine approaches in Mendelian disease diagnosis. Despite their success, the current diagnostic rate for genomic analyses across a variety of rare diseases is approximately 25 to 50%. We explore the utility of transcriptome sequencing [RNA sequencing (RNA-seq)] as a complementary diagnostic tool in a cohort of 50 patients with genetically undiagnosed rare muscle disorders. We describe an integrated approach to analyze patient muscle RNA-seq, leveraging an analysis framework focused on the detection of transcript-level changes that are unique to the patient compared to more than 180 control skeletal muscle samples. We demonstrate the power of RNA-seq to validate candidate splice-disrupting mutations and to identify splice-altering variants in both exonic and deep intronic regions, yielding an overall diagnosis rate of 35%. We also report the discovery of a highly recurrent de novo intronic mutation in COL6A1 that results in a dominantly acting splice-gain event, disrupting the critical glycine repeat motif of the triple helical domain. We identify this pathogenic variant in a total of 27 genetically unsolved patients in an external collagen VI-like dystrophy cohort, thus explaining approximately 25% of patients clinically suggestive of having collagen VI dystrophy in whom prior genetic analysis is negative. Overall, this study represents a large systematic application of transcriptome sequencing to rare disease diagnosis and highlights its utility for the detection and interpretation of variants missed by current standard diagnostic approaches.


Assuntos
Sequenciamento de Nucleotídeos em Larga Escala/métodos , Transcriptoma/genética , Colágeno Tipo VI/genética , Colágeno Tipo VI/metabolismo , Humanos , Doenças Musculares/genética , Doenças Musculares/metabolismo , Mutação
11.
Hum Mutat ; 38(5): 517-523, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28229513

RESUMO

The clinical interpretation of genetic variants has come to rely heavily on reference population databases such as the Exome Aggregation Consortium (ExAC) database. Pathogenic variants in genes associated with severe, pediatric-onset, highly penetrant, autosomal dominant conditions are assumed to be absent or rare in these databases. Exome sequencing of a 6-year-old female patient with seizures, developmental delay, dysmorphic features, and failure to thrive identified an ASXL1 variant previously reported as causative of Bohring-Opitz syndrome (BOS). Surprisingly, the variant was observed seven times in the ExAC database, presumably in individuals without BOS. Although the BOS phenotype fit, the presence of the variant in reference population databases introduced ambiguity in result interpretation. Review of the literature revealed that acquired somatic mosaicism of ASXL1 variants (including pathogenic variants) during hematopoietic clonal expansion can occur with aging in healthy individuals. We examined all ASXL1 truncating variants in the ExAC database and determined most are likely somatic. Failure to consider somatic mosaicism may lead to the inaccurate assumption that conditions like BOS have reduced penetrance, or the misclassification of potentially pathogenic variants.


Assuntos
Craniossinostoses/diagnóstico , Craniossinostoses/genética , Estudos de Associação Genética , Mutação em Linhagem Germinativa , Deficiência Intelectual/diagnóstico , Deficiência Intelectual/genética , Mutação , Proteínas Repressoras/genética , Idoso , Idoso de 80 Anos ou mais , Alelos , Substituição de Aminoácidos , Pré-Escolar , Bases de Dados Genéticas , Facies , Feminino , Estudos de Associação Genética/métodos , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Fenótipo
12.
Nucleic Acids Res ; 45(D1): D840-D845, 2017 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-27899611

RESUMO

Worldwide, hundreds of thousands of humans have had their genomes or exomes sequenced, and access to the resulting data sets can provide valuable information for variant interpretation and understanding gene function. Here, we present a lightweight, flexible browser framework to display large population datasets of genetic variation. We demonstrate its use for exome sequence data from 60 706 individuals in the Exome Aggregation Consortium (ExAC). The ExAC browser provides gene- and transcript-centric displays of variation, a critical view for clinical applications. Additionally, we provide a variant display, which includes population frequency and functional annotation data as well as short read support for the called variant. This browser is open-source, freely available at http://exac.broadinstitute.org, and has already been used extensively by clinical laboratories worldwide.


Assuntos
Biologia Computacional/métodos , Bases de Dados Genéticas , Exoma , Genômica/métodos , Navegador , Estudo de Associação Genômica Ampla/métodos , Humanos , Software , Interface Usuário-Computador
13.
Am J Hum Genet ; 99(5): 1086-1105, 2016 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-27745833

RESUMO

This study establishes PYROXD1 variants as a cause of early-onset myopathy and uses biospecimens and cell lines, yeast, and zebrafish models to elucidate the fundamental role of PYROXD1 in skeletal muscle. Exome sequencing identified recessive variants in PYROXD1 in nine probands from five families. Affected individuals presented in infancy or childhood with slowly progressive proximal and distal weakness, facial weakness, nasal speech, swallowing difficulties, and normal to moderately elevated creatine kinase. Distinctive histopathology showed abundant internalized nuclei, myofibrillar disorganization, desmin-positive inclusions, and thickened Z-bands. PYROXD1 is a nuclear-cytoplasmic pyridine nucleotide-disulphide reductase (PNDR). PNDRs are flavoproteins (FAD-binding) and catalyze pyridine-nucleotide-dependent (NAD/NADH) reduction of thiol residues in other proteins. Complementation experiments in yeast lacking glutathione reductase glr1 show that human PYROXD1 has reductase activity that is strongly impaired by the disease-associated missense mutations. Immunolocalization studies in human muscle and zebrafish myofibers demonstrate that PYROXD1 localizes to the nucleus and to striated sarcomeric compartments. Zebrafish with ryroxD1 knock-down recapitulate features of PYROXD1 myopathy with sarcomeric disorganization, myofibrillar aggregates, and marked swimming defect. We characterize variants in the oxidoreductase PYROXD1 as a cause of early-onset myopathy with distinctive histopathology and introduce altered redox regulation as a primary cause of congenital muscle disease.


Assuntos
Núcleo Celular/genética , Miopatias Distais/genética , Variação Genética , Miopatias Congênitas Estruturais/genética , Oxirredutases/genética , Sequência de Aminoácidos , Animais , Células COS , Núcleo Celular/metabolismo , Cercopithecus aethiops , Estudos de Coortes , Creatina Quinase/genética , Creatina Quinase/metabolismo , Citoplasma/metabolismo , Miopatias Distais/patologia , Proteína Semelhante a ELAV 4/genética , Proteína Semelhante a ELAV 4/metabolismo , Feminino , Flavoproteínas/metabolismo , Deleção de Genes , Estudo de Associação Genômica Ampla , Glutationa Redutase/genética , Glutationa Redutase/metabolismo , Células HEK293 , Humanos , Masculino , Músculo Esquelético/patologia , Mutação de Sentido Incorreto , Miopatias Congênitas Estruturais/patologia , Oxirredutases/metabolismo , Linhagem , Conformação Proteica , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Peixe-Zebra/genética
14.
Nature ; 536(7616): 285-91, 2016 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-27535533

RESUMO

Large-scale reference data sets of human genetic variation are critical for the medical and functional interpretation of DNA sequence changes. Here we describe the aggregation and analysis of high-quality exome (protein-coding region) DNA sequence data for 60,706 individuals of diverse ancestries generated as part of the Exome Aggregation Consortium (ExAC). This catalogue of human genetic diversity contains an average of one variant every eight bases of the exome, and provides direct evidence for the presence of widespread mutational recurrence. We have used this catalogue to calculate objective metrics of pathogenicity for sequence variants, and to identify genes subject to strong selection against various classes of mutation; identifying 3,230 genes with near-complete depletion of predicted protein-truncating variants, with 72% of these genes having no currently established human disease phenotype. Finally, we demonstrate that these data can be used for the efficient filtering of candidate disease-causing variants, and for the discovery of human 'knockout' variants in protein-coding genes.


Assuntos
Exoma/genética , Variação Genética/genética , Análise Mutacional de DNA , Conjuntos de Dados como Assunto , Humanos , Fenótipo , Proteoma/genética , Doenças Raras/genética , Tamanho da Amostra
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA