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1.
Clin Genet ; 106(1): 13-26, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38685133

RESUMO

The gold standard for facioscapulohumeral muscular dystrophy (FSHD) genetic diagnostic procedures was published in 2012. With the increasing complexity of the genetics of FSHD1 and 2, the increase of genetic testing centers, and the start of clinical trials for FSHD, it is crucial to provide an update on our knowledge of the genetic features of the FSHD loci and renew the international consensus on the molecular testing recommendations. To this end, members of the FSHD European Trial Network summarized the evidence presented during the 2022 ENMC meeting on Genetic diagnosis, clinical outcome measures, and biomarkers. The working group additionally invited genetic and clinical experts from the USA, India, Japan, Australia, South-Africa, and Brazil to provide a global perspective. Six virtual meetings were organized to reach consensus on the minimal requirements for genetic confirmation of FSHD1 and FSHD2. Here, we present the clinical and genetic features of FSHD, specific features of FSHD1 and FSHD2, pros and cons of established and new technologies (Southern blot in combination with either linear or pulsed-field gel electrophoresis, molecular combing, optical genome mapping, FSHD2 methylation analysis and FSHD2 genotyping), the possibilities and challenges of prenatal testing, including pre-implantation genetic testing, and the minimal requirements and recommendations for genetic confirmation of FSHD1 and FSHD2. This consensus is expected to contribute to current clinical management and trial-readiness for FSHD.


Assuntos
Testes Genéticos , Distrofia Muscular Facioescapuloumeral , Distrofia Muscular Facioescapuloumeral/genética , Distrofia Muscular Facioescapuloumeral/diagnóstico , Humanos , Testes Genéticos/normas , Testes Genéticos/métodos , Guias de Prática Clínica como Assunto
2.
Eur J Hum Genet ; 2024 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-38664571

RESUMO

Facioscapulohumeral muscular dystrophy (FSHD) is the third most common form of hereditary myopathy. Sixty per cent of the world's population lives in Asia, so a significant percentage of the world's FSHD participants is expected to live there. To date, most FSHD studies have involved individuals of European descent, yet small-scale studies of East-Asian populations suggest that the likelihood of developing FSHD may vary. Here, we present the first genetically confirmed FSHD cohort of Indian ancestry, which suggests a pathogenic FSHD1 allele size distribution intermediate between European and North-East Asian populations and more asymptomatic carriers of 4 unit and 5 unit FSHD1 alleles than observed in European populations. Our data provides important evidence of differences relevant to clinical diagnostics and underscores the need for global FSHD participation in research and trial-ready Indian FSHD cohorts.

3.
Hum Mol Genet ; 33(8): 698-708, 2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38268317

RESUMO

Identifying the aberrant expression of DUX4 in skeletal muscle as the cause of facioscapulohumeral dystrophy (FSHD) has led to rational therapeutic development and clinical trials. Several studies support the use of MRI characteristics and the expression of DUX4-regulated genes in muscle biopsies as biomarkers of FSHD disease activity and progression. We performed lower-extremity MRI and muscle biopsies in the mid-portion of the tibialis anterior (TA) muscles bilaterally in FSHD subjects and validated our prior reports of the strong association between MRI characteristics and expression of genes regulated by DUX4 and other gene categories associated with FSHD disease activity. We further show that measurements of normalized fat content in the entire TA muscle strongly predict molecular signatures in the mid-portion of the TA, indicating that regional biopsies can accurately measure progression in the whole muscle and providing a strong basis for inclusion of MRI and molecular biomarkers in clinical trial design. An unanticipated finding was the strong correlations of molecular signatures in the bilateral comparisons, including markers of B-cells and other immune cell populations, suggesting that a systemic immune cell infiltration of skeletal muscle might have a role in disease progression.


Assuntos
Distrofia Muscular Facioescapuloumeral , Humanos , Distrofia Muscular Facioescapuloumeral/diagnóstico por imagem , Distrofia Muscular Facioescapuloumeral/genética , Distrofia Muscular Facioescapuloumeral/metabolismo , Proteínas de Homeodomínio/genética , Ensaios Clínicos como Assunto , Músculo Esquelético/metabolismo , Imageamento por Ressonância Magnética , Biomarcadores/metabolismo , Progressão da Doença
4.
Brain ; 147(2): 414-426, 2024 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-37703328

RESUMO

Facioscapulohumeral dystrophy (FSHD) has a unique genetic aetiology resulting in partial chromatin relaxation of the D4Z4 macrosatellite repeat array on 4qter. This D4Z4 chromatin relaxation facilitates inappropriate expression of the transcription factor DUX4 in skeletal muscle. DUX4 is encoded by a retrogene that is embedded within the distal region of the D4Z4 repeat array. In the European population, the D4Z4 repeat array is usually organized in a single array that ranges between 8 and 100 units. D4Z4 chromatin relaxation and DUX4 derepression in FSHD is most often caused by repeat array contraction to 1-10 units (FSHD1) or by a digenic mechanism requiring pathogenic variants in a D4Z4 chromatin repressor like SMCHD1, combined with a repeat array between 8 and 20 units (FSHD2). With a prevalence of 1.5% in the European population, in cis duplications of the D4Z4 repeat array, where two adjacent D4Z4 arrays are interrupted by a spacer sequence, are relatively common but their relationship to FSHD is not well understood. In cis duplication alleles were shown to be pathogenic in FSHD2 patients; however, there is inconsistent evidence for the necessity of an SMCHD1 mutation for disease development. To explore the pathogenic nature of these alleles we compared in cis duplication alleles in FSHD patients with or without pathogenic SMCHD1 variant. For both groups we showed duplication-allele-specific DUX4 expression. We studied these alleles in detail using pulsed-field gel electrophoresis-based Southern blotting and molecular combing, emphasizing the challenges in the characterization of these rearrangements. Nanopore sequencing was instrumental to study the composition and methylation of the duplicated D4Z4 repeat arrays and to identify the breakpoints and the spacer sequence between the arrays. By comparing the composition of the D4Z4 repeat array of in cis duplication alleles in both groups, we found that specific combinations of proximal and distal repeat array sizes determine their pathogenicity. Supported by our algorithm to predict pathogenicity, diagnostic laboratories should now be furnished to accurately interpret these in cis D4Z4 repeat array duplications, alleles that can easily be missed in routine settings.


Assuntos
Distrofia Muscular Facioescapuloumeral , Humanos , Distrofia Muscular Facioescapuloumeral/genética , Distrofia Muscular Facioescapuloumeral/metabolismo , Distrofia Muscular Facioescapuloumeral/patologia , Alelos , Proteínas Cromossômicas não Histona/genética , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Cromatina
5.
Biomolecules ; 13(11)2023 10 24.
Artigo em Inglês | MEDLINE | ID: mdl-38002249

RESUMO

Facioscapulohumeral muscular dystrophy (FSHD) is the second most common muscular dystrophy in adults, and it is associated with local D4Z4 chromatin relaxation, mostly via the contraction of the D4Z4 macrosatellite repeat array on chromosome 4q35. In this study, we aimed to investigate the use of Optical Genome Mapping (OGM) as a diagnostic tool for testing FSHD cases from the UK and India and to compare OGM performance with that of traditional techniques such as linear gel (LGE) and Pulsed-field gel electrophoresis (PFGE) Southern blotting (SB). A total of 6 confirmed and 19 suspected FSHD samples were processed with LGE and PFGE, respectively. The same samples were run using a Saphyr Genome-Imaging Instrument (1-color), and the data were analysed using custom EnFocus FSHD analysis. OGM was able to confirm the diagnosis of FSHD1 in all FSHD1 cases positive for SB (n = 17), and D4Z4 sizing highly correlated with PFGE-SB (p < 0.001). OGM correctly identified cases with mosaicism for the repeat array contraction (n = 2) and with a duplication of the D4Z4 repeat array. OGM is a promising new technology able to unravel structural variants in the genome and seems to be a valid tool for diagnosing FSHD1.


Assuntos
Distrofia Muscular Facioescapuloumeral , Adulto , Humanos , Distrofia Muscular Facioescapuloumeral/diagnóstico , Distrofia Muscular Facioescapuloumeral/genética , Eletroforese em Gel de Campo Pulsado , Mapeamento Cromossômico , Índia
6.
Cell Rep ; 42(9): 113114, 2023 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-37691147

RESUMO

The transcription factor DUX4 regulates a portion of the zygotic gene activation (ZGA) program in the early embryo. Many cancers express DUX4 but it is unknown whether this generates cells similar to early embryonic stem cells. Here we identified cancer cell lines that express DUX4 and showed that DUX4 is transiently expressed in a small subset of the cells. DUX4 expression activates the DUX4-regulated ZGA transcriptional program, the subsequent 8C-like program, and markers of early embryonic lineages, while suppressing steady-state and interferon-induced MHC class I expression. Although DUX4 was expressed in a small number of cells under standard culture conditions, DNA damage or changes in growth conditions increased the fraction of cells expressing DUX4 and its downstream programs. Our demonstration that transient expression of endogenous DUX4 in cancer cells induces a metastable early embryonic stem cell program and suppresses antigen presentation has implications for cancer growth, progression, and immune evasion.


Assuntos
Distrofia Muscular Facioescapuloumeral , Neoplasias , Humanos , Linhagem Celular , Genes Homeobox , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Distrofia Muscular Facioescapuloumeral/genética , Neoplasias/genética , Neoplasias/metabolismo , Fatores de Transcrição/metabolismo , Zigoto/metabolismo
7.
Brain ; 146(12): 5098-5109, 2023 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-37516995

RESUMO

Neuromuscular diseases (NMDs) affect ∼15 million people globally. In high income settings DNA-based diagnosis has transformed care pathways and led to gene-specific therapies. However, most affected families are in low-to-middle income countries (LMICs) with limited access to DNA-based diagnosis. Most (86%) published genetic data is derived from European ancestry. This marked genetic data inequality hampers understanding of genetic diversity and hinders accurate genetic diagnosis in all income settings. We developed a cloud-based transcontinental partnership to build diverse, deeply-phenotyped and genetically characterized cohorts to improve genetic architecture knowledge, and potentially advance diagnosis and clinical management. We connected 18 centres in Brazil, India, South Africa, Turkey, Zambia, Netherlands and the UK. We co-developed a cloud-based data solution and trained 17 international neurology fellows in clinical genomic data interpretation. Single gene and whole exome data were analysed via a bespoke bioinformatics pipeline and reviewed alongside clinical and phenotypic data in global webinars to inform genetic outcome decisions. We recruited 6001 participants in the first 43 months. Initial genetic analyses 'solved' or 'possibly solved' ∼56% probands overall. In-depth genetic data review of the four commonest clinical categories (limb girdle muscular dystrophy, inherited peripheral neuropathies, congenital myopathy/muscular dystrophies and Duchenne/Becker muscular dystrophy) delivered a ∼59% 'solved' and ∼13% 'possibly solved' outcome. Almost 29% of disease causing variants were novel, increasing diverse pathogenic variant knowledge. Unsolved participants represent a new discovery cohort. The dataset provides a large resource from under-represented populations for genetic and translational research. In conclusion, we established a remote transcontinental partnership to assess genetic architecture of NMDs across diverse populations. It supported DNA-based diagnosis, potentially enabling genetic counselling, care pathways and eligibility for gene-specific trials. Similar virtual partnerships could be adopted by other areas of global genomic neurological practice to reduce genetic data inequality and benefit patients globally.


Assuntos
Distrofia Muscular do Cíngulo dos Membros , Distrofias Musculares , Doenças Neuromusculares , Doenças do Sistema Nervoso Periférico , Humanos , Doenças Neuromusculares/genética , Distrofia Muscular do Cíngulo dos Membros/diagnóstico , DNA
9.
bioRxiv ; 2023 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-36865168

RESUMO

Identifying the aberrant expression of DUX4 in skeletal muscle as the cause of facioscapulohumeral dystrophy (FSHD) has led to rational therapeutic development and clinical trials. Several studies support the use of MRI characteristics and the expression of DUX4-regulated genes in muscle biopsies as biomarkers of FSHD disease activity and progression, but reproducibility across studies needs further validation. We performed lower-extremity MRI and muscle biopsies in the mid-portion of the tibialis anterior (TA) muscles bilaterally in FSHD subjects and validated our prior reports of the strong association between MRI characteristics and expression of genes regulated by DUX4 and other gene categories associated with FSHD disease activity. We further show that measurements of normalized fat content in the entire TA muscle strongly predict molecular signatures in the mid-portion of the TA. Together with moderate-to-strong correlations of gene signatures and MRI characteristics between the TA muscles bilaterally, these results suggest a whole muscle model of disease progression and provide a strong basis for inclusion of MRI and molecular biomarkers in clinical trial design.

10.
Ann Clin Transl Neurol ; 9(8): 1302-1309, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35734998

RESUMO

Many individuals with muscular dystrophies remain genetically undiagnosed despite clinical diagnostic testing, including exome sequencing. Some may harbor previously undetected structural variants (SVs) or cryptic splice sites. We enrolled 10 unrelated families: nine had muscular dystrophy but lacked complete genetic diagnoses and one had an asymptomatic DMD duplication. Nanopore genomic long-read sequencing identified previously undetected pathogenic variants in four individuals: an SV in DMD, an SV in LAMA2, and two single nucleotide variants in DMD that alter splicing. The DMD duplication in the asymptomatic individual was in tandem. Nanopore sequencing may help streamline genetic diagnostic approaches for muscular dystrophy.


Assuntos
Distrofia Muscular de Duchenne , Sequenciamento por Nanoporos , Nanoporos , Humanos , Distrofia Muscular de Duchenne/diagnóstico , Distrofia Muscular de Duchenne/genética , Sequenciamento do Exoma
11.
J Med Genet ; 59(2): 180-188, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-33436523

RESUMO

BACKGROUND: Facioscapulohumeral dystrophy (FSHD) is an inherited muscular dystrophy clinically characterised by muscle weakness starting with the facial and upper extremity muscles. A disease model has been developed that postulates that failure in somatic repression of the transcription factor DUX4 embedded in the D4Z4 repeat on chromosome 4q causes FSHD. However, due to the position of the D4Z4 repeat close to the telomere and the complex genetic and epigenetic aetiology of FSHD, there is ongoing debate about the transcriptional deregulation of closely linked genes and their involvement in FSHD. METHOD: Detailed genetic characterisation and gene expression analysis of patients with clinically confirmed FSHD and control individuals. RESULTS: Identification of two FSHD families in which the disease is caused by repeat contraction and DUX4 expression from chromosome 10 due to a de novo D4Z4 repeat exchange between chromosomes 4 and 10. We show that the genetic lesion causal to FSHD in these families is physically separated from other candidate genes on chromosome 4. We demonstrate that muscle cell cultures from affected family members exhibit the characteristic molecular features of FSHD, including DUX4 and DUX4 target gene expression, without showing evidence for transcriptional deregulation of other chromosome 4-specific candidate genes. CONCLUSION: This study shows that in rare situations, FSHD can occur on chromosome 10 due to an interchromosomal rearrangement with the FSHD locus on chromosome 4q. These findings provide further evidence that DUX4 derepression is the dominant disease pathway for FSHD. Hence, therapeutic strategies should focus on DUX4 as the primary target.


Assuntos
Cromossomos Humanos Par 10 , Proteínas de Homeodomínio/genética , Distrofia Muscular Facioescapuloumeral/genética , Adulto , Células Cultivadas , Pontos de Quebra do Cromossomo , Cromossomos Humanos Par 4 , Feminino , Estudos de Associação Genética , Humanos , Masculino , Linhagem , Sequências Repetitivas de Ácido Nucleico , Transcriptoma
12.
Hum Mol Genet ; 31(5): 748-760, 2022 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-34559225

RESUMO

Facioscapulohumeral muscular dystrophy (FSHD) is an inherited myopathy clinically characterized by weakness in the facial, shoulder girdle and upper a muscles. FSHD is caused by chromatin relaxation of the D4Z4 macrosatellite repeat, mostly by a repeat contraction, facilitating ectopic expression of DUX4 in skeletal muscle. Genetic diagnosis for FSHD is generally based on the sizing and haplotyping of the D4Z4 repeat on chromosome 4 by Southern blotting (SB), molecular combing or single-molecule optical mapping, which is usually straight forward but can be complicated by atypical rearrangements of the D4Z4 repeat. One of these rearrangements is a D4Z4 proximally extended deletion (DPED) allele, where not only the D4Z4 repeat is partially deleted, but also sequences immediately proximal to the repeat are lost, which can impede accurate diagnosis in all genetic methods. Previously, we identified several DPED alleles in FSHD and estimated the size of the proximal deletions by a complex pulsed-field gel electrophoresis and SB strategy. Here, using the next-generation sequencing, we have defined the breakpoint junctions of these DPED alleles at the base pair resolution in 12 FSHD families and 4 control individuals facilitating a PCR-based diagnosis of these DPED alleles. Our resultsshow that half of the DPED alleles are derivates of an ancient founder allele. For some DPED alleles, we found that genetic elements are deleted such as DUX4c, FRG2, DBE-T and myogenic enhancers necessitating re-evaluation of their role in FSHD pathogenesis.


Assuntos
Distrofia Muscular Facioescapuloumeral , Alelos , Cromatina , Cromossomos Humanos Par 4/genética , Efeito Fundador , Humanos , Distrofia Muscular Facioescapuloumeral/genética , Distrofia Muscular Facioescapuloumeral/metabolismo
13.
Neurology ; 94(23): e2441-e2447, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32467133

RESUMO

OBJECTIVE: Facioscapulohumeral muscular dystrophy (FSHD) is a heterogenetic disorder predominantly characterized by progressive facial and scapular muscle weakness. Patients with FSHD either have a contraction of the D4Z4 repeat on chromosome 4q35 or mutations in D4Z4 chromatin modifiers SMCHD1 and DNMT3B, both causing D4Z4 chromatin relaxation and inappropriate expression of the D4Z4-encoded DUX4 gene in skeletal muscle. In this study, we tested the hypothesis whether LRIF1, a known SMCHD1 protein interactor, is a disease gene for idiopathic FSHD2. METHODS: Clinical examination of a patient with idiopathic FSHD2 was combined with pathologic muscle biopsy examination and with genetic, epigenetic, and molecular studies. RESULTS: A homozygous LRIF1 mutation was identified in a patient with a clinical phenotype consistent with FSHD. This mutation resulted in the absence of the long isoform of LRIF1 protein, D4Z4 chromatin relaxation, and DUX4 and DUX4 target gene expression in myonuclei, all molecular and epigenetic hallmarks of FSHD. In concordance, LRIF1 was shown to bind to the D4Z4 repeat, and knockdown of the LRIF1 long isoform in muscle cells results in DUX4 and DUX4 target gene expression. CONCLUSION: LRIF1 is a bona fide disease gene for FSHD2. This study further reinforces the unifying genetic mechanism, which postulates that FSHD is caused by D4Z4 chromatin relaxation, resulting in inappropriate DUX4 expression in skeletal muscle.


Assuntos
Proteínas de Ciclo Celular/genética , Distrofia Muscular Facioescapuloumeral/genética , Biópsia , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/metabolismo , Células Cultivadas , Cromatina/ultraestrutura , Proteínas Cromossômicas não Histona/metabolismo , Cromossomos Humanos Par 4/genética , Códon sem Sentido , Consanguinidade , Fibroblastos , Mutação da Fase de Leitura , Duplicação Gênica , Regulação da Expressão Gênica , Proteínas de Homeodomínio/biossíntese , Proteínas de Homeodomínio/genética , Homozigoto , Humanos , Masculino , Pessoa de Meia-Idade , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/patologia , Linhagem , Isoformas de Proteínas/genética , Sequências Repetitivas de Ácido Nucleico
14.
Hum Mol Genet ; 29(6): 1030-1043, 2020 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-32083293

RESUMO

Advances in understanding the pathophysiology of facioscapulohumeral dystrophy (FSHD) have led to the discovery of candidate therapeutics, and it is important to identify markers of disease activity to inform clinical trial design. For drugs that inhibit DUX4 expression, measuring DUX4 or DUX4-target gene expression might be an interim measure of drug activity; however, only a subset of FHSD muscle biopsies shows evidence of DUX4 expression. Our prior study showed that MRI T2-STIR-positive muscles had a higher probability of showing DUX4 expression than muscles with normal MRI characteristics. In the current study, we performed a 1-year follow-up assessment of the same muscle with repeat MRI and muscle biopsy. There was little change in MRI characteristics over the 1-year period and, similar to the initial evaluation, MRI T2-STIR-postive muscles had a higher expression of DUX4-regulated genes, as well as genes associated with inflammation, extracellular matrix and cell cycle. Compared to the initial evaluation, overall the level of expression in these gene categories remained stable over the 1-year period; however, there was some variability for each individual muscle biopsied. The pooled data from both the initial and 1-year follow-up evaluations identified several FSHD subgroups based on gene expression, as well as a set of genes-composed of DUX4-target genes, inflammatory and immune genes and cell cycle control genes-that distinguished all of the FSHD samples from the controls. These candidate markers of disease activity need to be replicated in independent datasets and, if validated, may provide useful measures of disease progression and response to therapy.


Assuntos
Biomarcadores/análise , Regulação da Expressão Gênica , Proteínas de Homeodomínio/genética , Músculo Esquelético/patologia , Distrofia Muscular Facioescapuloumeral/genética , Distrofia Muscular Facioescapuloumeral/patologia , RNA-Seq/métodos , Adulto , Idoso , Estudos de Casos e Controles , Feminino , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/metabolismo , Adulto Jovem
15.
J Med Genet ; 56(12): 828-837, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31676591

RESUMO

BACKGROUND: Facioscapulohumeral dystrophy (FSHD) is associated with partial chromatin relaxation of the DUX4 retrogene containing D4Z4 macrosatellite repeats on chromosome 4, and transcriptional de-repression of DUX4 in skeletal muscle. The common form of FSHD, FSHD1, is caused by a D4Z4 repeat array contraction. The less common form, FSHD2, is generally caused by heterozygous variants in SMCHD1. METHODS: We employed whole exome sequencing combined with Sanger sequencing to screen uncharacterised FSHD2 patients for extra-exonic SMCHD1 mutations. We also used CRISPR-Cas9 genome editing to repair a pathogenic intronic SMCHD1 variant from patient myoblasts. RESULTS: We identified intronic SMCHD1 variants in two FSHD families. In the first family, an intronic variant resulted in partial intron retention and inclusion of the distal 14 nucleotides of intron 13 into the transcript. In the second family, a deep intronic variant in intron 34 resulted in exonisation of 53 nucleotides of intron 34. In both families, the aberrant transcripts are predicted to be non-functional. Deleting the pseudo-exon by CRISPR-Cas9 mediated genome editing in primary and immortalised myoblasts from the index case of the second family restored wild-type SMCHD1 expression to a level that resulted in efficient suppression of DUX4. CONCLUSIONS: The estimated intronic mutation frequency of almost 2% in FSHD2, as exemplified by the two novel intronic SMCHD1 variants identified here, emphasises the importance of screening for intronic variants in SMCHD1. Furthermore, the efficient suppression of DUX4 after restoring SMCHD1 levels by genome editing of the mutant allele provides further guidance for therapeutic strategies.


Assuntos
Proteínas Cromossômicas não Histona/genética , Proteínas de Homeodomínio/genética , Distrofia Muscular Facioescapuloumeral/genética , Adulto , Idoso , Alelos , Sistemas CRISPR-Cas/genética , Cromatina/genética , Montagem e Desmontagem da Cromatina/genética , Cromossomos Humanos Par 4/genética , Metilação de DNA/genética , Feminino , Edição de Genes/métodos , Expressão Gênica/genética , Predisposição Genética para Doença , Humanos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Distrofia Muscular Facioescapuloumeral/fisiopatologia , Distrofia Muscular Facioescapuloumeral/terapia , Mutação/genética
16.
Stem Cell Res ; 40: 101560, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31518905

RESUMO

Facioscapulohumeral dystrophy type 1 (FSHD1) is caused by contraction of the D4Z4 repeat array on chromosome 4q resulting in sporadic misexpression of the transcription factor DUX4 in skeletal muscle tissue. In ~4% of families, de novo D4Z4 contractions occur after fertilization resulting in somatic mosaicism with control and FSHD1 cell populations present within the same patient. Reprogramming of mosaic fibroblasts from two FSHD1 patients into human induced pluripotent stem cells (hiPSCs) generated genetically matched control and FSHD1 hiPSC lines. All hiPSC lines contained a normal karyotype, expressed pluripotency genes and differentiated into cells from the three germ layers.


Assuntos
Linhagem Celular/citologia , Células-Tronco Pluripotentes Induzidas/citologia , Distrofia Muscular Facioescapuloumeral/genética , Diferenciação Celular , Linhagem Celular/metabolismo , Reprogramação Celular , Fibroblastos/citologia , Fibroblastos/metabolismo , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Masculino , Pessoa de Meia-Idade , Distrofia Muscular Facioescapuloumeral/metabolismo , Distrofia Muscular Facioescapuloumeral/fisiopatologia , Mutação
17.
J Med Genet ; 56(10): 693-700, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31243061

RESUMO

BACKGROUND: Variants in the Structural Maintenance of Chromosomes flexible Hinge Domain-containing protein 1 (SMCHD1) can cause facioscapulohumeral muscular dystrophy type 2 (FSHD2) and the unrelated Bosma arhinia microphthalmia syndrome (BAMS). In FSHD2, pathogenic variants are found anywhere in SMCHD1 while in BAMS, pathogenic variants are restricted to the extended ATPase domain. Irrespective of the phenotypic outcome, both FSHD2-associated and BAMS-associated SMCHD1 variants result in quantifiable local DNA hypomethylation. We compared FSHD2, BAMS and non-pathogenic SMCHD1 variants to derive genotype-phenotype relationships. METHODS: Examination of SMCHD1 variants and methylation of the SMCHD1-sensitive FSHD locus DUX4 in 187 FSHD2 families, 41 patients with BAMS and in control individuals. Analysis of variants in a three-dimensional model of the ATPase domain of SMCHD1. RESULTS: DUX4 methylation analysis is essential to establish pathogenicity of SMCHD1 variants. Although the FSHD2 mutation spectrum includes all types of variants covering the entire SMCHD1 locus, missense variants are significantly enriched in the extended ATPase domain. Identification of recurrent variants suggests disease-specific residues for FSHD2 and in BAMS, consistent with a largely disease-specific localisation of variants in SMCHD1. CONCLUSIONS: The localisation of missense variants within the ATPase domain of SMCHD1 may contribute to the differences in phenotypic outcome.


Assuntos
Atresia das Cóanas/genética , Proteínas Cromossômicas não Histona/genética , Microftalmia/genética , Distrofia Muscular Facioescapuloumeral/genética , Nariz/anormalidades , Adenosina Trifosfatases/genética , Metilação de DNA , Feminino , Variação Genética , Humanos , Masculino , Mutação , Mutação de Sentido Incorreto , Domínios Proteicos
18.
Neurology ; 92(19): e2273-e2285, 2019 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-30979860

RESUMO

OBJECTIVE: To compare the clinical features of patients showing a classical phenotype of facioscapulohumeral muscular dystrophy (FSHD) with genetic and epigenetic characteristics of the FSHD1 and FSHD2 loci D4Z4 and SMCHD1. METHODS: This is a national multicenter cohort study. We measured motor strength, motor function, and disease severity by manual muscle testing sumscore, Brooke and Vignos scores, clinical severity score (CSS), and age-corrected CSS, respectively. We correlated these scores with genetic (D4Z4 repeat size and haplotype; SMCHD1 variant status) and epigenetic (D4Z4 methylation) parameters. RESULTS: We included 103 patients: 54 men and 49 women. Among them, we identified 64 patients with FSHD1 and 20 patients with FSHD2. Seven patients had genetic and epigenetic characteristics of FSHD1 and FSHD2, all carrying repeats of 9-10 D4Z4 repeat units (RU) and a pathogenic SMCHD1 variant. In the remaining patients, FSHD was genetically excluded or remained unconfirmed. All clinically affected SMCHD1 mutation carriers had a D4Z4 repeat of 9-16 RU on a disease permissive 4qA haplotype. These patients are significantly more severely affected by all clinical scales when compared to patients with FSHD1 with upper-sized FSHD1 alleles (8-10 RU). CONCLUSION: The overlap between FSHD1 and FSHD2 patients in the 9-10 D4Z4 RU range suggests that FSHD1 and FSHD2 form a disease continuum. The previously established repeat size threshold for FSHD1 (1-10 RU) and FSHD2 (11-20 RU) needs to be reconsidered. CLINICALTRIALSGOV IDENTIFIER: NCT01970735.


Assuntos
Metilação de DNA , Força Muscular/fisiologia , Distrofia Muscular Facioescapuloumeral/diagnóstico , Mutação , Adulto , Alelos , Proteínas Cromossômicas não Histona/genética , Feminino , Haplótipos , Humanos , Masculino , Pessoa de Meia-Idade , Distrofia Muscular Facioescapuloumeral/genética , Distrofia Muscular Facioescapuloumeral/fisiopatologia , Fenótipo , Índice de Gravidade de Doença
19.
Hum Mol Genet ; 28(3): 476-486, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30312408

RESUMO

Facioscapulohumeral muscular dystrophy (FSHD) is a common, dominantly inherited disease caused by the epigenetic de-repression of the DUX4 gene, a transcription factor normally repressed in skeletal muscle. As targeted therapies are now possible in FSHD, a better understanding of the relationship between DUX4 activity, muscle pathology and muscle magnetic resonance imaging (MRI) changes is crucial both to understand disease mechanisms and for the design of future clinical trials. Here, we performed MRIs of the lower extremities in 36 individuals with FSHD, followed by needle muscle biopsies in safely accessible muscles. We examined the correlation between MRI characteristics, muscle pathology and expression of DUX4 target genes. Results show that the presence of elevated MRI short tau inversion recovery signal has substantial predictive value in identifying muscles with active disease as determined by histopathology and DUX4 target gene expression. In addition, DUX4 target gene expression was detected only in FSHD-affected muscles and not in control muscles. These results support the use of MRI to identify FSHD muscles most likely to have active disease and higher levels of DUX4 target gene expression and might be useful in early phase therapeutic trials to demonstrate target engagement in therapies aiming to suppress DUX4 expression.


Assuntos
Proteínas de Homeodomínio/genética , Músculo Esquelético/patologia , Distrofia Muscular Facioescapuloumeral/diagnóstico por imagem , Adulto , Idoso , Biópsia , Feminino , Expressão Gênica , Proteínas de Homeodomínio/biossíntese , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/metabolismo , Distrofia Muscular Facioescapuloumeral/genética , Distrofia Muscular Facioescapuloumeral/metabolismo , Distrofia Muscular Facioescapuloumeral/patologia , Fatores de Transcrição/genética
20.
Neurology ; 92(4): e378-e385, 2019 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-30568007

RESUMO

OBJECTIVE: To assess the relation between age at onset and disease severity in facioscapulohumeral muscular dystrophy (FSHD). METHODS: In this prospective cross-sectional study, we matched adult patients with FSHD with an early disease onset with 2 sex-matched FSHD control groups with a classic onset; the first group was age matched, and the second group was disease duration matched. Genetic characteristics, muscle performance, respiratory functioning, hearing loss, vision loss, epilepsy, educational level, and work status were compared with the 2 control groups. RESULTS: Twenty-eight patients with early-onset FSHD were age (n = 28) or duration (n = 27) matched with classic-onset patients. Patients with early-onset FSHD had more severe muscle weakness (mean FSHD clinical score 11 vs 5 in the age-matched and 9 in the duration-matched group, p < 0.05) and a higher frequency of wheelchair dependency (57%, 0%, and 30%, respectively, p < 0.05). In addition, systemic features were more frequent in early-onset FSHD, most important, hearing loss, decreased respiratory function and spinal deformities. There was no difference in work status. Genetically, the shortest D4Z4 repeat arrays (2-3 units) were found exclusively in the early-onset group, and the largest repeat arrays (8-9 units) were found only in the classic-onset groups. De novo mutations were more frequent in early-onset patients (46% vs 4%). CONCLUSIONS: Patients with early-onset FSHD more often have severe muscle weakness and systemic features. The disease severity is greater than in patients with classic-onset FSHD who are matched for disease duration, suggesting that the progression is faster in early-onset patients.


Assuntos
Idade de Início , Distrofia Muscular Facioescapuloumeral/diagnóstico , Distrofia Muscular Facioescapuloumeral/fisiopatologia , Adulto , Idoso , Cegueira/etiologia , Estudos Transversais , Expansão das Repetições de DNA/genética , Epilepsia/etiologia , Feminino , Perda Auditiva/etiologia , Proteínas de Homeodomínio/genética , Humanos , Masculino , Pessoa de Meia-Idade , Debilidade Muscular/etiologia , Estudos Prospectivos , Índice de Gravidade de Doença
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