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Guruju NM, Jump V, Lemmers R, Van Der Maarel S, Liu R, Nallamilli BR, Shenoy S, Chaubey A, Koppikar P, Rose R, Khadilkar S, Hegde M. Molecular Diagnosis of Facioscapulohumeral Muscular Dystrophy in Patients Clinically Suspected of FSHD Using Optical Genome Mapping. Neurol Genet 2023; 9:e200107. [PMID: 38021397 PMCID: PMC10664978 DOI: 10.1212/nxg.0000000000200107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 09/18/2023] [Indexed: 12/01/2023]
Abstract
Background and Objectives Facioscapulohumeral muscular dystrophy (FSHD) represents the third most common muscular dystrophy in the general population and is characterized by progressive and often asymmetric muscle weakness of the face, upper extremities, arms, lower leg, and hip girdle. In FSHD type 1, contraction of the number of D4Z4 repeats to 1-10 on the chromosome 4-permissive allele (4qA) results in abnormal epigenetic derepression of the DUX4 gene in skeletal muscle. In FSHD type 2, epigenetic derepression of the DUX4 gene on the permissive allele (4qA) with normal-sized D4Z4 repeats (mostly 8-20) is caused by heterozygous pathogenic variants in chromatin modifier genes such as SMCHD1, DNMT3B, or LRIF1. We present validation of the optical genome mapping (OGM) platform for accurate mapping of the D4Z4 repeat size, followed by diagnostic testing of 547 cases with a suspected clinical diagnosis of FSHD and next-generation sequencing (NGS) of the SMCHD1 gene to identify cases with FSHD2. Methods OGM with Bionano Genomics Saphyr and EnFocus FSHD analysis software was used to identify FSHD haplotypes and D4Z4 repeat number and compared with the gold standard of Southern blot-based diagnosis. A custom Agilent SureSelect enrichment kit was used to enrich SMCHD1, followed by NGS on an Illumina system with 100-bp paired-end reads. Copy number variants were assessed using NxClinical software. Results We performed OGM for the diagnosis of FSHD in 547 patients suspected of FSHD between December 2019 and December 2022, including 301 male (55%) and 246 female patients (45%). Overall, 308 of the referred patients were positive for D4Z4 contraction on a permissive haplotype, resulting in a diagnosis of FSHD1. A total of 252 of 547 patients were referred for concurrent testing for FSHD1 and FSHD2. This resulted in the identification of FSHD2 in 9/252 (3.6%) patients. In our FSHD2 cohort, the 4qA allele size ranged from 8 to 18 repeats. Among FSHD1-positive cases, 2 patients had biallelic contraction and 4 patients had homozygous contraction and showed early onset of clinical features. Nine of the 308 patients (3%) positive for 4qA contraction had mosaic 4q alleles with contraction on at least one 4qA allele. The overall diagnostic yield in our cohort was 58%. Discussion A combination of OGM to identify the FSHD haplotype and D4Z4 repeat number and NGS to identify sequence and copy number variants in the SMCHD1 gene is a practical and cost-effective option with increased precision for accurate diagnosis of FSHD types 1 and 2.
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Affiliation(s)
- Naga M Guruju
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Vanessa Jump
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Richard Lemmers
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Silvere Van Der Maarel
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Ruby Liu
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Babi R Nallamilli
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Suresh Shenoy
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Alka Chaubey
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Pratik Koppikar
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Rajiv Rose
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Satish Khadilkar
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Madhuri Hegde
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
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Kovanda A, Lovrečić L, Rudolf G, Babic Bozovic I, Jaklič H, Leonardis L, Peterlin B. Evaluation of Optical Genome Mapping in Clinical Genetic Testing of Facioscapulohumeral Muscular Dystrophy. Genes (Basel) 2023; 14:2166. [PMID: 38136988 PMCID: PMC10743191 DOI: 10.3390/genes14122166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 11/24/2023] [Accepted: 11/27/2023] [Indexed: 12/24/2023] Open
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is the third most common hereditary muscular dystrophy, caused by the contraction of the D4Z4 repeats on the permissive 4qA haplotype on chromosome 4, resulting in the faulty expression of the DUX4 gene. Traditional diagnostics are based on Southern blotting, a time- and effort-intensive method that can be affected by single nucleotide variants (SNV) and copy number variants (CNV), as well as by the similarity of the D4Z4 repeats located on chromosome 10. We aimed to evaluate optical genome mapping (OGM) as an alternative molecular diagnostic method for the detection of FSHD. We first performed optical genome mapping with EnFocus™ FSHD analysis using DLE-1 labeling and the Saphyr instrument in patients with inconclusive diagnostic Southern blot results, negative FSHD2 results, and clinically evident FSHD. Second, we performed OGM in parallel with the classical Southern blot analysis for our prospectively collected new FSHD cases. Finally, panel exome sequencing was performed to confirm the presence of FSHD2. In two patients with diagnostically inconclusive Southern blot results, OGM was able to identify shortened D4Z4 repeats on the permissive 4qA alleles, consistent with the clinical presentation. The results of the prospectively collected patients tested in parallel using Southern blotting and OGM showed full concordance, indicating that OGM is a useful alternative to the classical Southern blotting method for detecting FSHD1. In a patient showing clinical FSHD but no shortened D4Z4 repeats in the 4qA allele using OGM or Southern blotting, a likely pathogenic variant in SMCHD1 was detected using exome sequencing, confirming FSHD2. OGM and panel exome sequencing can be used consecutively to detect FSHD2.
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Affiliation(s)
- Anja Kovanda
- Clinical Institute of Genomic Medicine, University Medical Center, 1000 Ljubljana, Slovenia; (A.K.)
- Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Luca Lovrečić
- Clinical Institute of Genomic Medicine, University Medical Center, 1000 Ljubljana, Slovenia; (A.K.)
- Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Gorazd Rudolf
- Clinical Institute of Genomic Medicine, University Medical Center, 1000 Ljubljana, Slovenia; (A.K.)
- Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Ivana Babic Bozovic
- Clinical Institute of Genomic Medicine, University Medical Center, 1000 Ljubljana, Slovenia; (A.K.)
| | - Helena Jaklič
- Clinical Institute of Genomic Medicine, University Medical Center, 1000 Ljubljana, Slovenia; (A.K.)
| | - Lea Leonardis
- Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
- Institute of Clinical Neurophysiology, University Medical Center Ljubljana, 1000 Ljubljana, Slovenia
| | - Borut Peterlin
- Clinical Institute of Genomic Medicine, University Medical Center, 1000 Ljubljana, Slovenia; (A.K.)
- Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
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Efthymiou S, Lemmers RJLF, Vishnu VY, Dominik N, Perrone B, Facchini S, Vegezzi E, Ravaglia S, Wilson L, van der Vliet PJ, Mishra R, Reyaz A, Ahmad T, Bhatia R, Polke JM, Srivastava MP, Cortese A, Houlden H, van der Maarel SM, Hanna MG, Bugiardini E. Optical Genome Mapping for the Molecular Diagnosis of Facioscapulohumeral Muscular Dystrophy: Advancement and Challenges. Biomolecules 2023; 13:1567. [PMID: 38002249 PMCID: PMC10669274 DOI: 10.3390/biom13111567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 09/21/2023] [Accepted: 09/29/2023] [Indexed: 11/26/2023] Open
Abstract
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.
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Affiliation(s)
- Stephanie Efthymiou
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; (S.E.); (N.D.); (B.P.); (L.W.); (H.H.)
| | - Richard J. L. F. Lemmers
- Department of Human Genetics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands (S.M.v.d.M.)
| | - Venugopalan Y. Vishnu
- Department of Neurology, All India Institute of Medical Sciences, New Delhi 110029, India; (V.Y.V.); (R.M.); (A.R.); (R.B.); (M.P.S.)
| | - Natalia Dominik
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; (S.E.); (N.D.); (B.P.); (L.W.); (H.H.)
| | - Benedetta Perrone
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; (S.E.); (N.D.); (B.P.); (L.W.); (H.H.)
| | - Stefano Facchini
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; (S.E.); (N.D.); (B.P.); (L.W.); (H.H.)
| | - Elisa Vegezzi
- IRCCS Mondino Foundation, 27100 Pavia, Italy; (E.V.); (S.R.)
| | | | - Lindsay Wilson
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; (S.E.); (N.D.); (B.P.); (L.W.); (H.H.)
| | - Patrick J. van der Vliet
- Department of Human Genetics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands (S.M.v.d.M.)
| | - Rinkle Mishra
- Department of Neurology, All India Institute of Medical Sciences, New Delhi 110029, India; (V.Y.V.); (R.M.); (A.R.); (R.B.); (M.P.S.)
| | - Alisha Reyaz
- Department of Neurology, All India Institute of Medical Sciences, New Delhi 110029, India; (V.Y.V.); (R.M.); (A.R.); (R.B.); (M.P.S.)
| | - Tanveer Ahmad
- Department of Neurology, All India Institute of Medical Sciences, New Delhi 110029, India; (V.Y.V.); (R.M.); (A.R.); (R.B.); (M.P.S.)
| | - Rohit Bhatia
- Department of Neurology, All India Institute of Medical Sciences, New Delhi 110029, India; (V.Y.V.); (R.M.); (A.R.); (R.B.); (M.P.S.)
| | - James M. Polke
- Neurogenetics Laboratory, National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK;
| | - Mv Padma Srivastava
- Department of Neurology, All India Institute of Medical Sciences, New Delhi 110029, India; (V.Y.V.); (R.M.); (A.R.); (R.B.); (M.P.S.)
| | - Andrea Cortese
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; (S.E.); (N.D.); (B.P.); (L.W.); (H.H.)
- IRCCS Mondino Foundation, 27100 Pavia, Italy; (E.V.); (S.R.)
| | - Henry Houlden
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; (S.E.); (N.D.); (B.P.); (L.W.); (H.H.)
| | - Silvère M. van der Maarel
- Department of Human Genetics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands (S.M.v.d.M.)
| | - Michael G. Hanna
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; (S.E.); (N.D.); (B.P.); (L.W.); (H.H.)
| | - Enrico Bugiardini
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; (S.E.); (N.D.); (B.P.); (L.W.); (H.H.)
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Duranti E, Villa C. Influence of DUX4 Expression in Facioscapulohumeral Muscular Dystrophy and Possible Treatments. Int J Mol Sci 2023; 24:ijms24119503. [PMID: 37298453 DOI: 10.3390/ijms24119503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 05/23/2023] [Accepted: 05/29/2023] [Indexed: 06/12/2023] Open
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) represents the third most common form of muscular dystrophy and is characterized by muscle weakness and atrophy. FSHD is caused by the altered expression of the transcription factor double homeobox 4 (DUX4), which is involved in several significantly altered pathways required for myogenesis and muscle regeneration. While DUX4 is normally silenced in the majority of somatic tissues in healthy individuals, its epigenetic de-repression has been linked to FSHD, resulting in DUX4 aberrant expression and cytotoxicity in skeletal muscle cells. Understanding how DUX4 is regulated and functions could provide useful information not only to further understand FSHD pathogenesis, but also to develop therapeutic approaches for this disorder. Therefore, this review discusses the role of DUX4 in FSHD by examining the possible molecular mechanisms underlying the disease as well as novel pharmacological strategies targeting DUX4 aberrant expression.
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Affiliation(s)
- Elisa Duranti
- School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy
| | - Chiara Villa
- School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy
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Claus C, Slavin M, Ansseau E, Lancelot C, Bah K, Lassche S, Fiévet M, Greco A, Tomaiuolo S, Tassin A, Dudome V, Kusters B, Declèves AE, Laoudj-Chenivesse D, van Engelen BGM, Nonclercq D, Belayew A, Kalisman N, Coppée F. The double homeodomain protein DUX4c is associated with regenerating muscle fibers and RNA-binding proteins. Skelet Muscle 2023; 13:5. [PMID: 36882853 PMCID: PMC9990282 DOI: 10.1186/s13395-022-00310-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 11/30/2022] [Indexed: 03/09/2023] Open
Abstract
BACKGROUND We have previously demonstrated that double homeobox 4 centromeric (DUX4C) encoded for a functional DUX4c protein upregulated in dystrophic skeletal muscles. Based on gain- and loss-of-function studies we have proposed DUX4c involvement in muscle regeneration. Here, we provide further evidence for such a role in skeletal muscles from patients affected with facioscapulohumeral muscular dystrophy (FSHD). METHODS DUX4c was studied at RNA and protein levels in FSHD muscle cell cultures and biopsies. Its protein partners were co-purified and identified by mass spectrometry. Endogenous DUX4c was detected in FSHD muscle sections with either its partners or regeneration markers using co-immunofluorescence or in situ proximity ligation assay. RESULTS We identified new alternatively spliced DUX4C transcripts and confirmed DUX4c immunodetection in rare FSHD muscle cells in primary culture. DUX4c was detected in nuclei, cytoplasm or at cell-cell contacts between myocytes and interacted sporadically with specific RNA-binding proteins involved, a.o., in muscle differentiation, repair, and mass maintenance. In FSHD muscle sections, DUX4c was found in fibers with unusual shape or central/delocalized nuclei (a regeneration feature) staining for developmental myosin heavy chain, MYOD or presenting intense desmin labeling. Some couples of myocytes/fibers locally exhibited peripheral DUX4c-positive areas that were very close to each other, but in distinct cells. MYOD or intense desmin staining at these locations suggested an imminent muscle cell fusion. We further demonstrated DUX4c interaction with its major protein partner, C1qBP, inside myocytes/myofibers that presented features of regeneration. On adjacent muscle sections, we could unexpectedly detect DUX4 (the FSHD causal protein) and its interaction with C1qBP in fusing myocytes/fibers. CONCLUSIONS DUX4c upregulation in FSHD muscles suggests it contributes not only to the pathology but also, based on its protein partners and specific markers, to attempts at muscle regeneration. The presence of both DUX4 and DUX4c in regenerating FSHD muscle cells suggests DUX4 could compete with normal DUX4c functions, thus explaining why skeletal muscle is particularly sensitive to DUX4 toxicity. Caution should be exerted with therapeutic agents aiming for DUX4 suppression because they might also repress the highly similar DUX4c and interfere with its physiological role.
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Affiliation(s)
- Clothilde Claus
- Laboratory of Metabolic and Molecular Biochemistry, Research Institute for Health Sciences and Technology, University of Mons, 6, Avenue du Champs de Mars, B-7000, Mons, Belgium
| | - Moriya Slavin
- Department of Biological Chemistry, the Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Eugénie Ansseau
- Laboratory of Metabolic and Molecular Biochemistry, Research Institute for Health Sciences and Technology, University of Mons, 6, Avenue du Champs de Mars, B-7000, Mons, Belgium
| | - Céline Lancelot
- Laboratory of Metabolic and Molecular Biochemistry, Research Institute for Health Sciences and Technology, University of Mons, 6, Avenue du Champs de Mars, B-7000, Mons, Belgium
| | - Karimatou Bah
- Laboratory of Metabolic and Molecular Biochemistry, Research Institute for Health Sciences and Technology, University of Mons, 6, Avenue du Champs de Mars, B-7000, Mons, Belgium
| | - Saskia Lassche
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands.,Department of Neurology, Zuyderland Medical Center, Heerlen, the Netherlands
| | - Manon Fiévet
- Laboratory of Metabolic and Molecular Biochemistry, Research Institute for Health Sciences and Technology, University of Mons, 6, Avenue du Champs de Mars, B-7000, Mons, Belgium
| | - Anna Greco
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Sara Tomaiuolo
- Laboratory of Metabolic and Molecular Biochemistry, Research Institute for Health Sciences and Technology, University of Mons, 6, Avenue du Champs de Mars, B-7000, Mons, Belgium
| | - Alexandra Tassin
- Laboratory of Metabolic and Molecular Biochemistry, Research Institute for Health Sciences and Technology, University of Mons, 6, Avenue du Champs de Mars, B-7000, Mons, Belgium.,Laboratory of Respiratory Physiology and Rehabilitation, Research Institute for Health Sciences and Technology, University of Mons, 6, Avenue du Champs de Mars, B-7000, Mons, Belgium
| | - Virginie Dudome
- Laboratory of Metabolic and Molecular Biochemistry, Research Institute for Health Sciences and Technology, University of Mons, 6, Avenue du Champs de Mars, B-7000, Mons, Belgium
| | - Benno Kusters
- Department of Pathology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Anne-Emilie Declèves
- Laboratory of Metabolic and Molecular Biochemistry, Research Institute for Health Sciences and Technology, University of Mons, 6, Avenue du Champs de Mars, B-7000, Mons, Belgium
| | | | - Baziel G M van Engelen
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Denis Nonclercq
- Laboratory of Histology, Research Institute for Health Sciences and Technology, University of Mons, 6, Avenue du Champs de Mars, B-7000, Mons, Belgium
| | - Alexandra Belayew
- Laboratory of Metabolic and Molecular Biochemistry, Research Institute for Health Sciences and Technology, University of Mons, 6, Avenue du Champs de Mars, B-7000, Mons, Belgium
| | - Nir Kalisman
- Department of Biological Chemistry, the Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Frédérique Coppée
- Laboratory of Metabolic and Molecular Biochemistry, Research Institute for Health Sciences and Technology, University of Mons, 6, Avenue du Champs de Mars, B-7000, Mons, Belgium.
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Tihaya MS, Mul K, Balog J, de Greef JC, Tapscott SJ, Tawil R, Statland JM, van der Maarel SM. Facioscapulohumeral muscular dystrophy: the road to targeted therapies. Nat Rev Neurol 2023; 19:91-108. [PMID: 36627512 DOI: 10.1038/s41582-022-00762-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/07/2022] [Indexed: 01/11/2023]
Abstract
Advances in the molecular understanding of facioscapulohumeral muscular dystrophy (FSHD) have revealed that FSHD results from epigenetic de-repression of the DUX4 gene in skeletal muscle, which encodes a transcription factor that is active in early embryonic development but is normally silenced in almost all somatic tissues. These advances also led to the identification of targets for disease-altering therapies for FSHD, as well as an improved understanding of the molecular mechanism of the disease and factors that influence its progression. Together, these developments led the FSHD research community to shift its focus towards the development of disease-modifying treatments for FSHD. This Review presents advances in the molecular and clinical understanding of FSHD, discusses the potential targeted therapies that are currently being explored, some of which are already in clinical trials, and describes progress in the development of FSHD-specific outcome measures and assessment tools for use in future clinical trials.
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Affiliation(s)
- Mara S Tihaya
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Karlien Mul
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Judit Balog
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Jessica C de Greef
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Stephen J Tapscott
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Rabi Tawil
- Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA
| | - Jeffrey M Statland
- Department of Neurology, University of Kansas Medical Center, Kansas City, KS, USA
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Ganassi M, Figeac N, Reynaud M, Ortuste Quiroga HP, Zammit PS. Antagonism Between DUX4 and DUX4c Highlights a Pathomechanism Operating Through β-Catenin in Facioscapulohumeral Muscular Dystrophy. Front Cell Dev Biol 2022; 10:802573. [PMID: 36158201 PMCID: PMC9490378 DOI: 10.3389/fcell.2022.802573] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 06/17/2022] [Indexed: 11/13/2022] Open
Abstract
Aberrant expression of the transcription factor DUX4 from D4Z4 macrosatellite repeats on chromosome 4q35, and its transcriptome, associate with pathogenesis in facioscapulohumeral muscular dystrophy (FSHD). Forced DUX4 expression halts skeletal muscle cell proliferation and induces cell death. DUX4 binds DNA via two homeodomains that are identical in sequence to those of DUX4c (DUX4L9): a closely related transcriptional regulator encoded by a single, inverted, mutated D4Z4 unit located centromeric to the D4Z4 macrosatellite array on chromosome 4. However, the function and contribution of DUX4c to FSHD pathogenesis are unclear. To explore interplay between DUX4, DUX4c, and the DUX4-induced phenotype, we investigated whether DUX4c interferes with DUX4 function in human myogenesis. Constitutive expression of DUX4c rescued the DUX4-induced inhibition of proliferation and reduced cell death in human myoblasts. Functionally, DUX4 promotes nuclear translocation of β-CATENIN and increases canonical WNT signalling. Concomitant constitutive expression of DUX4c prevents β-CATENIN nuclear accumulation and the downstream transcriptional program. DUX4 reduces endogenous DUX4c levels, whereas constitutive expression of DUX4c robustly suppresses expression of DUX4 target genes, suggesting molecular antagonism. In line, DUX4 expression in FSHD myoblasts correlates with reduced DUX4c levels. Addressing the mechanism, we identified a subset of genes involved in the WNT/β-CATENIN pathway that are differentially regulated between DUX4 and DUX4c, whose expression pattern can separate muscle biopsies from severely affected FSHD patients from healthy. Finally, blockade of WNT/β-CATENIN signalling rescues viability of FSHD myoblasts. Together, our study highlights an antagonistic interplay whereby DUX4 alters cell viability via β-CATENIN signalling and DUX4c counteracts aspects of DUX4-mediated toxicity in human muscle cells, potentially acting as a gene modifier for FSHD severity. Importantly, direct DUX4 regulation of the WNT/β-CATENIN pathway informs future therapeutic interventions to ameliorate FSHD pathology.
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Affiliation(s)
| | | | | | | | - Peter S. Zammit
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
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8
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The evolution of DUX4 gene regulation and its implication for facioscapulohumeral muscular dystrophy. Biochim Biophys Acta Mol Basis Dis 2022; 1868:166367. [PMID: 35158020 PMCID: PMC9173005 DOI: 10.1016/j.bbadis.2022.166367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 01/26/2022] [Accepted: 02/07/2022] [Indexed: 11/22/2022]
Abstract
Double homeobox 4 (DUX4) is an early embryonic transcription factor whose expression in the skeletal muscle causes facioscapulohumeral muscular dystrophy (FSHD). Despite decades of research, our knowledge of FSHD and DUX4 biology is incomplete, and the disease has currently no cures or targeted therapies. The unusual evolutionary origin of DUX4, its extensive epigenetic and post-transcriptional gene regulation, and various feedback regulatory loops that control its expression and function all contribute to the highly complex nature of FSHD pathogenesis. In this minireview, I synthesize the current state of knowledge in DUX4 and FSHD biology to highlight key areas where further research is needed to better understand DUX4 regulation. I also emphasize post-transcriptional regulation of and by DUX4 via changes in RNA and protein stability that might underlie key features of FSHD pathophysiology. Finally, I discuss the various feedback loops involved in DUX4 regulation and the context-specific consequences of its expression, which could be key to developing novel therapeutic approaches to combat FSHD.
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9
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Distrofia muscolare facio-scapolo-omerale. Neurologia 2021. [DOI: 10.1016/s1634-7072(21)45785-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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10
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Lemmers RJLF, Vliet PJ, Granado DSL, Stoep N, Buermans H, Schendel R, Schimmel J, Visser M, Coster R, Jeanpierre M, Laforet P, Upadhyaya M, Engelen B, Sacconi S, Tawil R, Voermans NC, Rogers M, van der Maarel SM. High resolution breakpoint junction mapping of proximally extended D4Z4 deletions in FSHD1 reveals evidence for a founder effect. Hum Mol Genet 2021; 31:748-760. [PMID: 34559225 DOI: 10.1093/hmg/ddab250] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 08/17/2021] [Accepted: 08/24/2021] [Indexed: 01/09/2023] Open
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is an inherited myopathy clinically characterized by weakness in the facial, shoulder girdle and upper arm 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, 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 Southern blot strategy. Here, using 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 results show 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.
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Affiliation(s)
- Richard J L F Lemmers
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Patrick J Vliet
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Nienke Stoep
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Henk Buermans
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Robin Schendel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Joost Schimmel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Marianne Visser
- Academic Medical Center, Department of Neurology, Amsterdam, The Netherlands
| | - Rudy Coster
- Department of Pediatrics, Division of Pediatric Neurology, Ghent University Hospital, Ghent, Belgium
| | | | - Pascal Laforet
- Nord-Est/Ile-de-France Neuromuscular Reference Center, FHU PHENIX, Neurology Department, Raymond-Poincaré Hospital, Versailles Saint-Quentin-en-Yvelines - Paris Saclay University, Garches, France
| | - Meena Upadhyaya
- Department of Medical Genetics, Cardiff University, Cardif, UK
| | - Baziel Engelen
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University, The Netherlands
| | - Sabrina Sacconi
- Centre de référence des Maladies neuromusculaires, Nice University Hospital, Nice, France
| | - Rabi Tawil
- Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA
| | - Nicol C Voermans
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University, The Netherlands
| | - Mark Rogers
- Department of Medical Genetics, Cardiff University, Cardif, UK
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11
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Voermans NC, Vriens-Munoz Bravo M, Padberg GW, Laforêt P. 1st FSHD European Trial Network workshop:Working towards trial readiness across Europe. Neuromuscul Disord 2021; 31:907-918. [PMID: 34404575 DOI: 10.1016/j.nmd.2021.07.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 07/15/2021] [Indexed: 01/29/2023]
Affiliation(s)
- N C Voermans
- FSHD Europe, Radboud University Medical Centre, P.O. Box 9101, Nijmegen 6500 HB, the Netherlands.
| | - M Vriens-Munoz Bravo
- FSHD Europe, Radboud University Medical Centre, P.O. Box 9101, Nijmegen 6500 HB, the Netherlands
| | - G W Padberg
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - P Laforêt
- Nord-Est-Ile de France Neuromuscular Reference Center, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris Myology Institute, Neuromuscular Pathology Reference Center, Groupe Hospitalier Universitaire La Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, Paris, France
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12
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Lemmers RJLF, van der Vliet PJ, Blatnik A, Balog J, Zidar J, Henderson D, Goselink R, Tapscott SJ, Voermans NC, Tawil R, Padberg GWAM, van Engelen BG, van der Maarel SM. Chromosome 10q-linked FSHD identifies DUX4 as principal disease gene. J Med Genet 2021; 59:180-188. [PMID: 33436523 DOI: 10.1136/jmedgenet-2020-107041] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 10/05/2020] [Accepted: 11/14/2020] [Indexed: 01/24/2023]
Abstract
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.
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Affiliation(s)
- Richard J L F Lemmers
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Ana Blatnik
- Cancer Genetics Clinic, Institute of Oncology, Ljubljana, Slovenia
| | - Judit Balog
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Janez Zidar
- Division of Neurology, Institute of Clinical Neurophysiology, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Don Henderson
- Department of Neurology, University of Rochester Medical Center, Rochester, New York, USA
| | - Rianne Goselink
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Stephen J Tapscott
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Nicol C Voermans
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Rabi Tawil
- Department of Neurology, University of Rochester Medical Center, Rochester, New York, USA
| | - George W A M Padberg
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Baziel Gm van Engelen
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
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13
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Sidlauskaite E, Le Gall L, Mariot V, Dumonceaux J. DUX4 Expression in FSHD Muscles: Focus on Its mRNA Regulation. J Pers Med 2020; 10:E73. [PMID: 32731450 PMCID: PMC7564753 DOI: 10.3390/jpm10030073] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/22/2020] [Accepted: 07/24/2020] [Indexed: 12/11/2022] Open
Abstract
Facioscapulohumeral dystrophy (FSHD) is the most frequent muscular disease in adults. FSHD is characterized by a weakness and atrophy of a specific set of muscles located in the face, the shoulder, and the upper arms. FSHD patients may present different genetic defects, but they all present epigenetic alterations of the D4Z4 array located on the subtelomeric part of chromosome 4, leading to chromatin relaxation and, ultimately, to the aberrant expression of one gene called DUX4. Once expressed, DUX4 triggers a cascade of deleterious events, eventually leading to muscle dysfunction and cell death. Here, we review studies on DUX4 expression in skeletal muscle to determine the genetic/epigenetic factors and regulatory proteins governing DUX4 expression, with particular attention to the different transcripts and their very low expression in muscle.
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Affiliation(s)
- Eva Sidlauskaite
- NIHR Biomedical Research Centre, University College London, Great Ormond Street Institute of Child Health and Great Ormond Street Hospital NHS Trust, London WC1N 1EH, UK; (E.S.); (L.L.G.); (V.M.)
| | - Laura Le Gall
- NIHR Biomedical Research Centre, University College London, Great Ormond Street Institute of Child Health and Great Ormond Street Hospital NHS Trust, London WC1N 1EH, UK; (E.S.); (L.L.G.); (V.M.)
| | - Virginie Mariot
- NIHR Biomedical Research Centre, University College London, Great Ormond Street Institute of Child Health and Great Ormond Street Hospital NHS Trust, London WC1N 1EH, UK; (E.S.); (L.L.G.); (V.M.)
| | - Julie Dumonceaux
- NIHR Biomedical Research Centre, University College London, Great Ormond Street Institute of Child Health and Great Ormond Street Hospital NHS Trust, London WC1N 1EH, UK; (E.S.); (L.L.G.); (V.M.)
- Northern Ireland Center for Stratified/Personalised Medicine, Biomedical Sciences Research Institute, Ulster University, Derry~Londonderry, Northern Ireland BT47 6SB, UK
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14
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Lemmers RJLF, van der Vliet PJ, Vreijling JP, Henderson D, van der Stoep N, Voermans N, van Engelen B, Baas F, Sacconi S, Tawil R, van der Maarel SM. Cis D4Z4 repeat duplications associated with facioscapulohumeral muscular dystrophy type 2. Hum Mol Genet 2019; 27:3488-3497. [PMID: 30281091 DOI: 10.1093/hmg/ddy236] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 06/15/2018] [Indexed: 12/26/2022] Open
Abstract
Facioscapulohumeral muscular dystrophy, known in genetic forms FSHD1 and FSHD2, is associated with D4Z4 repeat array chromatin relaxation and somatic derepression of DUX4 located in D4Z4. A complete copy of DUX4 is present on 4qA chromosomes, but not on the D4Z4-like repeats of chromosomes 4qB or 10. Normally, the D4Z4 repeat varies between 8 and 100 units, while in FSHD1 it is only 1-10 units. In the rare genetic form FSHD2, a combination of a 4qA allele with a D4Z4 repeat size of 8-20 units and heterozygous pathogenic variants in the chromatin modifier SMCHD1 causes DUX4 derepression and disease. In this study, we identified 11/79 (14%) FSHD2 patients with unusually large 4qA alleles of 21-70 D4Z4 units. By a combination of Southern blotting and molecular combing, we show that 8/11 (73%) of these unusually large 4qA alleles represent duplication alleles in which the long D4Z4 repeat arrays are followed by a small FSHD-sized D4Z4 repeat array duplication. We also show that these duplication alleles are associated with DUX4 expression. This duplication allele frequency is significantly higher than in controls (2.9%), FSHD1 patients (1.4%) and in FSHD2 patients with typical 4qA alleles of 8-20 D4Z4 units (1.5%). Segregation analysis shows that, similar to typical 8-20 units FSHD2 alleles, duplication alleles only cause FSHD in combination with a pathogenic variant in SMCHD1. We conclude that cis duplications of D4Z4 repeats explain DUX4 expression and disease presentation in FSHD2 families with unusual long D4Z4 repeats on 4qA chromosomes.
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Affiliation(s)
| | | | - Jeroen P Vreijling
- Laboratory for Diagnostic Genome Analysis, Leiden University Medical Center, Leiden, RC, Netherlands
| | - Don Henderson
- Neuromuscular Disease Unit, Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA
| | - Nienke van der Stoep
- Laboratory for Diagnostic Genome Analysis, Leiden University Medical Center, Leiden, RC, Netherlands
| | - Nicol Voermans
- Neuromuscular Centre Nijmegen, Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, HB, Netherlands
| | - Baziel van Engelen
- Neuromuscular Centre Nijmegen, Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, HB, Netherlands
| | - Frank Baas
- Laboratory for Diagnostic Genome Analysis, Leiden University Medical Center, Leiden, RC, Netherlands
| | - Sabrina Sacconi
- Centre de Référence des Maladies Neuromusculaires and CNRS UMR6543, Nice University Hospital, Nice, France
| | - Rabi Tawil
- Neuromuscular Disease Unit, Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA
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15
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Nguyen K, Broucqsault N, Chaix C, Roche S, Robin JD, Vovan C, Gerard L, Mégarbané A, Urtizberea JA, Bellance R, Barnérias C, David A, Eymard B, Fradin M, Manel V, Sacconi S, Tiffreau V, Zagnoli F, Cuisset JM, Salort-Campana E, Attarian S, Bernard R, Lévy N, Magdinier F. Deciphering the complexity of the 4q and 10q subtelomeres by molecular combing in healthy individuals and patients with facioscapulohumeral dystrophy. J Med Genet 2019; 56:590-601. [PMID: 31010831 DOI: 10.1136/jmedgenet-2018-105949] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 02/28/2019] [Accepted: 03/24/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND Subtelomeres are variable regions between telomeres and chromosomal-specific regions. One of the most studied pathologies linked to subtelomeric imbalance is facioscapulohumeral dystrophy (FSHD). In most cases, this disease involves shortening of an array of D4Z4 macrosatellite elements at the 4q35 locus. The disease also segregates with a specific A-type haplotype containing a degenerated polyadenylation signal distal to the last repeat followed by a repetitive array of β-satellite elements. This classification applies to most patients with FSHD. A subset of patients called FSHD2 escapes this definition and carries a mutation in the SMCHD1 gene. We also recently described patients carrying a complex rearrangement consisting of a cis-duplication of the distal 4q35 locus identified by molecular combing. METHODS Using this high-resolution technology, we further investigated the organisation of the 4q35 region linked to the disease and the 10q26 locus presenting with 98% of homology in controls and patients. RESULTS Our analyses reveal a broad variability in size of the different elements composing these loci highlighting the complexity of these subtelomeres and the difficulty for genomic assembly. Out of the 1029 DNA samples analysed in our centre in the last 7 years, we also identified 54 cases clinically diagnosed with FSHD carrying complex genotypes. This includes mosaic patients, patients with deletions of the proximal 4q region and 23 cases with an atypical chromosome 10 pattern, infrequently found in the control population and never reported before. CONCLUSION Overall, this work underlines the complexity of these loci challenging the diagnosis and genetic counselling for this disease.
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Affiliation(s)
- Karine Nguyen
- Medical Genetics, Assistance Publique Hopitaux de Marseille, Marseille, France.,Aix Marseille Univ, INSERM, MMG, Marseille Medical Genetics U1251, Marseille, France
| | - Natacha Broucqsault
- Aix Marseille Univ, INSERM, MMG, Marseille Medical Genetics U1251, Marseille, France
| | - Charlene Chaix
- Medical Genetics, Assistance Publique Hopitaux de Marseille, Marseille, France
| | - Stephane Roche
- Aix Marseille Univ, INSERM, MMG, Marseille Medical Genetics U1251, Marseille, France
| | - Jérôme D Robin
- Aix Marseille Univ, INSERM, MMG, Marseille Medical Genetics U1251, Marseille, France
| | - Catherine Vovan
- Medical Genetics, Assistance Publique Hopitaux de Marseille, Marseille, France
| | - Laurene Gerard
- Medical Genetics, Assistance Publique Hopitaux de Marseille, Marseille, France
| | | | - Jon Andoni Urtizberea
- Pôle Soins de suite et réadaptation handicaps lourds et maladies rares neurologiques, Hôpital Marin, Assistance publique des hopitaux de Paris, Hendaye, France
| | - Remi Bellance
- Hopital Pierre Zobda-Quitman, Fort-de-France, France
| | - Christine Barnérias
- Service de Neurologie infantile, Université Paris Descartes, Sorbonne Paris Cité, Hôpital Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris, Paris, France.,Centre de Référence de Maladies Neuromusculaires Garches-Necker-Mondor-Hendaye (GNMH), Réseau National Français de la Filière Neuromusculaire (FILNEMUS), Paris, France
| | | | - Bruno Eymard
- Assistance Publique - Hopitaux de Paris, Paris, Île-de-France, France
| | - Melanie Fradin
- Service de Génétique Médicale, Centre De Référence Anomalies du Développement, CHU de Rennes, Rennes, France
| | - Véronique Manel
- Centre référent maladies neuromusculaires rares, Hospices Civils de Lyon, Hôpital Femme Mère Enfant, Bron, France
| | - Sabrina Sacconi
- Peripheral Nervous System, Muscle and ALS Department, Université Côte d'Azur, Nice, France.,Institute for Research on Cancer and Aging of Nice, Université Côte d'Azur, Faculty of Medicine, Nice, France
| | - Vincent Tiffreau
- Centre de Référence des Maladies Neuromusculaires, service de Médecine Physique et de Réadaptation, Centre hospitalier régionale de Lille, Lille, France
| | - Fabien Zagnoli
- Centre de Référence des Maladies Neuromusculaires, CHU Morvan, Brest, France
| | | | - Emmanuelle Salort-Campana
- Aix Marseille Univ, INSERM, MMG, Marseille Medical Genetics U1251, Marseille, France.,Centre de reference des maladies neuromusculaires, Assistance Publique Hopitaux de Marseille, Marseille, France
| | - Shahram Attarian
- Aix Marseille Univ, INSERM, MMG, Marseille Medical Genetics U1251, Marseille, France.,Centre de reference des maladies neuromusculaires, Assistance Publique Hopitaux de Marseille, Marseille, France
| | - Rafaëlle Bernard
- Medical Genetics, Assistance Publique Hopitaux de Marseille, Marseille, France.,Aix Marseille Univ, INSERM, MMG, Marseille Medical Genetics U1251, Marseille, France
| | - Nicolas Lévy
- Medical Genetics, Assistance Publique Hopitaux de Marseille, Marseille, France.,Aix Marseille Univ, INSERM, MMG, Marseille Medical Genetics U1251, Marseille, France
| | - Frederique Magdinier
- Aix Marseille Univ, INSERM, MMG, Marseille Medical Genetics U1251, Marseille, France
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16
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Zhang Q, Xu X, Ding L, Li H, Xu C, Gong Y, Liu Y, Mu T, Leigh D, Cram DS, Tang S. Clinical application of single-molecule optical mapping to a multigeneration FSHD1 pedigree. Mol Genet Genomic Med 2019; 7:e565. [PMID: 30666819 PMCID: PMC6418370 DOI: 10.1002/mgg3.565] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 12/12/2018] [Accepted: 12/13/2018] [Indexed: 01/06/2023] Open
Abstract
Introduction Facioscapulohumeral muscular dystrophy 1 (FSHD1) is a relatively common autosomal dominant adult muscular dystrophy with variable disease penetrance. The disease is caused by shortening of a D4Z4 repeat array located near the telomere of chromosome 4 at 4q35. This causes activation of a dormant gene DUX4, permitting aberrant DUX4 expression which is toxic to muscles. Molecular diagnosis of FSHD1 by Southern blot hybridization or FISH combing is difficult and time consuming, requiring specialist laboratories. As an alternative, we apply a novel approach for the diagnosis of FSHD1 utilizing single‐molecule optical mapping (SMOM). Methods Long DNA molecules with BssS1 enzyme marking were subjected to SMOM on the Bionano Genomics platform to determine the number of D4Z4 repeats. Southern blot and molecular combing were used to confirm the FSHD1 haplotypes. Results In a study of a five‐generation FSHD1 pedigree, SMOM correctly diagnosed the disease and normal haplotypes, identifying the founder 4qA disease allele as having 4 D4Z4 repeat units. Southern blot and molecular combing analysis confirmed the SMOM results for the 4qA disease and 4qB nondisease alleles. Conclusion Based on our findings, we propose that SMOM is a reliable and accurate technique suitable for the molecular diagnosis of FSHD1.
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Affiliation(s)
- Qian Zhang
- Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Xueqin Xu
- Wenzhou Key Laboratory of Birth Defects, Wenzhou Central Hospital, Wenzhou, China
| | - Lirong Ding
- Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Huanzheng Li
- Wenzhou Key Laboratory of Birth Defects, Wenzhou Central Hospital, Wenzhou, China
| | - Chengyang Xu
- Wenzhou Key Laboratory of Birth Defects, Wenzhou Central Hospital, Wenzhou, China
| | - Yuyan Gong
- Berry Genomics Corporation, Beijing, China
| | - Ying Liu
- Berry Genomics Corporation, Beijing, China
| | - Ting Mu
- Berry Genomics Corporation, Beijing, China
| | - Don Leigh
- The First Hospital of Kunming, Kunming, China
| | | | - Shaohua Tang
- Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China.,Wenzhou Key Laboratory of Birth Defects, Wenzhou Central Hospital, Wenzhou, China
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17
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DeSimone AM, Pakula A, Lek A, Emerson CP. Facioscapulohumeral Muscular Dystrophy. Compr Physiol 2017; 7:1229-1279. [PMID: 28915324 DOI: 10.1002/cphy.c160039] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Facioscapulohumeral Muscular Dystrophy is a common form of muscular dystrophy that presents clinically with progressive weakness of the facial, scapular, and humeral muscles, with later involvement of the trunk and lower extremities. While typically inherited as autosomal dominant, facioscapulohumeral muscular dystrophy (FSHD) has a complex genetic and epigenetic etiology that has only recently been well described. The most prevalent form of the disease, FSHD1, is associated with the contraction of the D4Z4 microsatellite repeat array located on a permissive 4qA chromosome. D4Z4 contraction allows epigenetic derepression of the array, and possibly the surrounding 4q35 region, allowing misexpression of the toxic DUX4 transcription factor encoded within the terminal D4Z4 repeat in skeletal muscles. The less common form of the disease, FSHD2, results from haploinsufficiency of the SMCHD1 gene in individuals carrying a permissive 4qA allele, also leading to the derepression of DUX4, further supporting a central role for DUX4. How DUX4 misexpression contributes to FSHD muscle pathology is a major focus of current investigation. Misexpression of other genes at the 4q35 locus, including FRG1 and FAT1, and unlinked genes, such as SMCHD1, has also been implicated as disease modifiers, leading to several competing disease models. In this review, we describe recent advances in understanding the pathophysiology of FSHD, including the application of MRI as a research and diagnostic tool, the genetic and epigenetic disruptions associated with the disease, and the molecular basis of FSHD. We discuss how these advances are leading to the emergence of new approaches to enable development of FSHD therapeutics. © 2017 American Physiological Society. Compr Physiol 7:1229-1279, 2017.
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Affiliation(s)
- Alec M DeSimone
- Wellstone Muscular Dystrophy Program, Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Anna Pakula
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA.,Department of Pediatrics and Genetics at Harvard Medical School, Boston, Massachusetts, USA
| | - Angela Lek
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA.,Department of Pediatrics and Genetics at Harvard Medical School, Boston, Massachusetts, USA.,Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria, Australia
| | - Charles P Emerson
- Wellstone Muscular Dystrophy Program, Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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Nguyen K, Puppo F, Roche S, Gaillard MC, Chaix C, Lagarde A, Pierret M, Vovan C, Olschwang S, Salort-Campana E, Attarian S, Bartoli M, Bernard R, Magdinier F, Levy N. Molecular combing reveals complex 4q35 rearrangements in Facioscapulohumeral dystrophy. Hum Mutat 2017; 38:1432-1441. [DOI: 10.1002/humu.23304] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Revised: 07/19/2017] [Accepted: 07/22/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Karine Nguyen
- Aix Marseille Université; INSERM GMGF UMR S_910; Marseille 13385 France
- APHM; Département de Génétique Médicale; Hôpital d'enfants de la Timone; Marseille 13385 France
| | - Francesca Puppo
- Aix Marseille Université; INSERM GMGF UMR S_910; Marseille 13385 France
| | - Stéphane Roche
- Aix Marseille Université; INSERM GMGF UMR S_910; Marseille 13385 France
| | | | - Charlène Chaix
- APHM; Département de Génétique Médicale; Hôpital d'enfants de la Timone; Marseille 13385 France
| | - Arnaud Lagarde
- Aix Marseille Université; INSERM GMGF UMR S_910; Marseille 13385 France
| | | | - Catherine Vovan
- APHM; Département de Génétique Médicale; Hôpital d'enfants de la Timone; Marseille 13385 France
| | - Sylviane Olschwang
- Aix Marseille Université; INSERM GMGF UMR S_910; Marseille 13385 France
- APHM; Département de Génétique Médicale; Hôpital d'enfants de la Timone; Marseille 13385 France
- Groupe Ramsay Générale de Santé; Hôpital Clairval; Marseille France
| | - Emmanuelle Salort-Campana
- Aix Marseille Université; INSERM GMGF UMR S_910; Marseille 13385 France
- APHM; Centre de Référence des Maladies Neuromusculaires et de la SLA; Hôpital de la Timone; Marseille 13385 France
| | - Shahram Attarian
- Aix Marseille Université; INSERM GMGF UMR S_910; Marseille 13385 France
- APHM; Centre de Référence des Maladies Neuromusculaires et de la SLA; Hôpital de la Timone; Marseille 13385 France
| | - Marc Bartoli
- Aix Marseille Université; INSERM GMGF UMR S_910; Marseille 13385 France
| | - Rafaëlle Bernard
- Aix Marseille Université; INSERM GMGF UMR S_910; Marseille 13385 France
- APHM; Département de Génétique Médicale; Hôpital d'enfants de la Timone; Marseille 13385 France
| | | | - Nicolas Levy
- Aix Marseille Université; INSERM GMGF UMR S_910; Marseille 13385 France
- APHM; Département de Génétique Médicale; Hôpital d'enfants de la Timone; Marseille 13385 France
- APHM; Centre de Ressources Biologiques; Hôpital de la Timone; Marseille 13385 France
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Himeda CL, Jones TI, Jones PL. CRISPR/dCas9-mediated Transcriptional Inhibition Ameliorates the Epigenetic Dysregulation at D4Z4 and Represses DUX4-fl in FSH Muscular Dystrophy. Mol Ther 2016; 24:527-35. [PMID: 26527377 PMCID: PMC4786914 DOI: 10.1038/mt.2015.200] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/21/2015] [Indexed: 12/16/2022] Open
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is one of the most prevalent myopathies, affecting males and females of all ages. Both forms of the disease are linked by epigenetic derepression of the D4Z4 macrosatellite repeat array at chromosome 4q35, leading to aberrant expression of D4Z4-encoded RNAs in skeletal muscle. Production of full-length DUX4 (DUX4-fl) mRNA from the derepressed D4Z4 array results in misexpression of DUX4-FL protein and its transcriptional targets, and apoptosis, ultimately leading to accumulated muscle pathology. Returning the chromatin at the FSHD locus to its nonpathogenic, epigenetically repressed state would simultaneously affect all D4Z4 RNAs, inhibiting downstream pathogenic pathways, and is thus an attractive therapeutic strategy. Advances in CRISPR/Cas9-based genome editing make it possible to target epigenetic modifiers to an endogenous disease locus, although reports to date have focused on more typical genomic regions. Here, we demonstrate that a CRISPR/dCas9 transcriptional inhibitor can be specifically targeted to the highly repetitive FSHD macrosatellite array and alter the chromatin to repress expression of DUX4-fl in primary FSHD myocytes. These results implicate the promoter and exon 1 of DUX4 as potential therapeutic targets and demonstrate the utility of CRISPR technology for correction of the epigenetic dysregulation in FSHD.
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Affiliation(s)
- Charis L Himeda
- The Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Takako I Jones
- The Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Peter L Jones
- The Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
- The Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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20
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Molecular combing compared to Southern blot for measuring D4Z4 contractions in FSHD. Neuromuscul Disord 2015; 25:945-51. [PMID: 26420234 DOI: 10.1016/j.nmd.2015.08.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 08/11/2015] [Accepted: 08/14/2015] [Indexed: 11/21/2022]
Abstract
We compare molecular combing to Southern blot in the analysis of the facioscapulohumeral muscular dystrophy type 1 locus (FSHD1) on chromosome 4q35-qter (chr 4q) in genomic DNA specimens sent to a clinical laboratory for FSHD testing. A de-identified set of 87 genomic DNA specimens determined by Southern blot as normal (n = 71), abnormal with D4Z4 macrosatellite repeat array contractions (n = 7), indeterminate (n = 6), borderline (n = 2), or mosaic (n = 1) was independently re-analyzed by molecular combing in a blinded fashion. The molecular combing results were identical to the Southern blot results in 75 (86%) of cases. All contractions (n = 7) and mosaics (n = 1) detected by Southern blot were confirmed by molecular combing. Of the 71 samples with normal Southern blot results, 67 (94%) had concordant molecular combing results. The four discrepancies were either mosaic (n = 2), rearranged (n = 1), or borderline by molecular combing (n = 1). All indeterminate Southern blot results (n = 6) were resolved by molecular combing as either normal (n = 4), borderline (n = 1), or rearranged (n = 1). The two borderline Southern blot results showed a D4Z4 contraction on the chr 4qA allele and a normal result by molecular combing. Molecular combing overcomes a number of technical limitations of Southern blot by providing direct visualization of D4Z4 macrosatellite repeat arrays on specific chr 4q and chr 10q alleles and more precise D4Z4 repeat sizing. This study suggests that molecular combing has superior analytical validity compared to Southern blot for determining D4Z4 contraction size, detecting mosaicism, and resolving borderline and indeterminate Southern blot results. Further studies are needed to establish the clinical validity and diagnostic accuracy of these findings in FSHD.
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21
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Hewitt JE. Loss of epigenetic silencing of the DUX4 transcription factor gene in facioscapulohumeral muscular dystrophy. Hum Mol Genet 2015; 24:R17-23. [PMID: 26113644 DOI: 10.1093/hmg/ddv237] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 06/18/2015] [Indexed: 02/07/2023] Open
Abstract
Current genetic and molecular evidence best supports an epigenetic mechanism for facioscapulohumeral muscular dystrophy (FSHD), whereby de-repression of the D4Z4 macrosatellite array leads to aberrant expression of the DUX4 transcription factor in skeletal muscle. This de-repression is triggered by either array contraction or (more rarely) by mutation of the SMCHD1 (structural maintenance of chromosomes flexible hinge domain containing 1) gene. Activation of DUX4 targets, including germline genes and several mammalian retrotransposons, then drives pathogenesis. A direct role for DUX4 mRNA in suppression of nonsense-mediated decay pathways has recently been demonstrated and may also contribute to muscle pathology. Loss of D4Z4 repression in FSHD is observed as hypomethylation of the array accompanied by loss of repressive chromatin marks. The molecular mechanisms of D4Z4 repression are poorly understood, but recent data have identified an Argonaute (AGO)-dependent siRNA pathway. Targeting this pathway by exogenous siRNAs could be a therapeutic strategy for FSHD.
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Affiliation(s)
- Jane E Hewitt
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
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22
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Ferri G, Huichalaf CH, Caccia R, Gabellini D. Direct interplay between two candidate genes in FSHD muscular dystrophy. Hum Mol Genet 2014; 24:1256-66. [PMID: 25326393 PMCID: PMC4321439 DOI: 10.1093/hmg/ddu536] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common neuromuscular disorders. The major form of the disease (FSHD1) is linked to decrease in copy number of a 3.3-kb tandem repeated macrosatellite (D4Z4), located on chromosome 4q35. D4Z4 deletion alters chromatin structure of the locus leading to aberrant expression of nearby 4q35 genes. Given the high variability in disease onset and progression, multiple factors could contribute to the pathogenesis of FSHD. Among the FSHD candidate genes are double homeobox 4 (DUX4), encoded by the most telomeric D4Z4 unit, and FSHD region gene 1 (FRG1). DUX4 is a sequence-specific transcription factor. Here, we located putative DUX4 binding sites in the human FRG1 genomic area and we show specific DUX4 association to these regions. We found also that ectopically expressed DUX4 up-regulates the endogenous human FRG1 gene in healthy muscle cells, while DUX4 knockdown leads to a decrease in FRG1 expression in FSHD muscle cells. Moreover, DUX4 binds directly and specifically to its binding site located in the human FRG1 gene and transactivates constructs containing FRG1 genomic regions. Intriguingly, the mouse Frg1 genomic area lacks DUX4 binding sites and DUX4 is unable to activate the endogenous mouse Frg1 gene providing a possible explanation for the lack of muscle phenotype in DUX4 transgenic mice. Altogether, our results demonstrate that FRG1 is a direct DUX4 transcriptional target uncovering a novel regulatory circuit contributing to FSHD.
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Affiliation(s)
- Giulia Ferri
- Division of Regenerative Medicine, Stem Cells, and Gene Therapy, Dulbecco Telethon Institute at San Raffaele Scientific Institute, DIBIT2, 5A3, Via Olgettina 58, 20132 Milan, Italy Università Vita-Salute San Raffaele, Milan, Italy
| | - Claudia H Huichalaf
- Division of Regenerative Medicine, Stem Cells, and Gene Therapy, Dulbecco Telethon Institute at San Raffaele Scientific Institute, DIBIT2, 5A3, Via Olgettina 58, 20132 Milan, Italy Università Vita-Salute San Raffaele, Milan, Italy
| | - Roberta Caccia
- Division of Regenerative Medicine, Stem Cells, and Gene Therapy, Dulbecco Telethon Institute at San Raffaele Scientific Institute, DIBIT2, 5A3, Via Olgettina 58, 20132 Milan, Italy
| | - Davide Gabellini
- Division of Regenerative Medicine, Stem Cells, and Gene Therapy, Dulbecco Telethon Institute at San Raffaele Scientific Institute, DIBIT2, 5A3, Via Olgettina 58, 20132 Milan, Italy
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23
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Himeda CL, Debarnot C, Homma S, Beermann ML, Miller JB, Jones PL, Jones TI. Myogenic enhancers regulate expression of the facioscapulohumeral muscular dystrophy-associated DUX4 gene. Mol Cell Biol 2014; 34:1942-55. [PMID: 24636994 PMCID: PMC4019064 DOI: 10.1128/mcb.00149-14] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 02/12/2014] [Accepted: 03/11/2014] [Indexed: 11/20/2022] Open
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is linked to epigenetic dysregulation of the chromosome 4q35 D4Z4 macrosatellite. However, this does not account for the tissue specificity of FSHD pathology, which requires stable expression of an alternative full-length mRNA splice form of DUX4 (DUX4-fl) from the D4Z4 array in skeletal muscle. Here, we describe the identification of two enhancers, DUX4 myogenic enhancer 1 (DME1) and DME2 which activate DUX4-fl expression in skeletal myocytes but not fibroblasts. Analysis of the chromatin revealed histone modifications and RNA polymerase II occupancy consistent with DME1 and DME2 being functional enhancers. Chromosome conformation capture analysis confirmed association of DME1 and DME2 with the DUX4 promoter in vivo. The strong interaction between DME2 and the DUX4 promoter in both FSHD and unaffected primary myocytes was greatly reduced in fibroblasts, suggesting a muscle-specific interaction. Nucleosome occupancy and methylome sequencing analysis indicated that in most FSHD myocytes, both enhancers are associated with nucleosomes but have hypomethylated DNA, consistent with a permissive transcriptional state, sporadic occupancy, and the observed DUX4 expression in rare myonuclei. Our data support a model in which these myogenic enhancers associate with the DUX4 promoter in skeletal myocytes and activate transcription when epigenetically derepressed in FSHD, resulting in the pathological misexpression of DUX4-fl.
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Affiliation(s)
- Charis L. Himeda
- Wellstone Program, Departments of Cell and Developmental Biology and Neurology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Céline Debarnot
- Ecole Supérieure de Biotechnologie Strasbourg, Illkirch, France
| | - Sachiko Homma
- Neuromuscular Biology and Disease Group, Departments of Neurology and Physiology Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Mary Lou Beermann
- Neuromuscular Biology and Disease Group, Departments of Neurology and Physiology Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jeffrey B. Miller
- Neuromuscular Biology and Disease Group, Departments of Neurology and Physiology Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Peter L. Jones
- Wellstone Program, Departments of Cell and Developmental Biology and Neurology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Takako I. Jones
- Wellstone Program, Departments of Cell and Developmental Biology and Neurology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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24
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Facioscapulohumeral muscular dystrophy. Biochim Biophys Acta Mol Basis Dis 2014; 1852:607-14. [PMID: 24882751 DOI: 10.1016/j.bbadis.2014.05.021] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 05/19/2014] [Accepted: 05/20/2014] [Indexed: 12/18/2022]
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is characterized by a typical and asymmetric pattern of muscle involvement and disease progression. Two forms of FSHD, FSHD1 and FSHD2, have been identified displaying identical clinical phenotype but different genetic and epigenetic basis. Autosomal dominant FSHD1 (95% of patients) is characterized by chromatin relaxation induced by pathogenic contraction of a macrosatellite repeat called D4Z4 located on the 4q subtelomere (FSHD1 patients harbor 1 to 10 D4Z4 repeated units). Chromatin relaxation is associated with inappropriate expression of DUX4, a retrogene, which in muscles induces apoptosis and inflammation. Consistent with this hypothesis, individuals carrying zero repeat on chromosome 4 do not develop FSHD1. Not all D4Z4 contracted alleles cause FSHD. Distal to the last D4Z4 unit, a polymorphic site with two allelic variants has been identified: 4qA and 4qB. 4qA is in cis with a functional polyadenylation consensus site. Only contractions on 4qA alleles are pathogenic because the DUX4 transcript is polyadenylated and translated into stable protein. FSHD2 is instead a digenic disease. Chromatin relaxation of the D4Z4 locus is caused by heterozygous mutations in the SMCHD1 gene encoding a protein essential for chromatin condensation. These patients also harbor at least one 4qA allele in order to express stable DUX4 transcripts. FSHD1 and FSHD2 may have an additive effect: patients harboring D4Z4 contraction and SMCHD1 mutations display a more severe clinical phenotype than with either defect alone. Knowledge of the complex genetic and epigenetic defects causing these diseases is essential in view of designing novel therapeutic strategies. This article is part of a Special Issue entitled: Neuromuscular Diseases: Pathology and Molecular Pathogenesis.
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25
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Salort-Campana E, Nguyen K, Lévy N, Pouget J, Attarian S. Diagnostic clinique et moléculaire de la myopathie facioscapulo-humérale de type 1 (FSHD1) en 2012. Rev Neurol (Paris) 2013; 169:573-82. [DOI: 10.1016/j.neurol.2013.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 07/10/2013] [Accepted: 07/15/2013] [Indexed: 01/20/2023]
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26
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Sacconi S, Desnuelle C. Dystrophie musculaire facio-scapulo-humérale de type 2. Rev Neurol (Paris) 2013; 169:564-72. [DOI: 10.1016/j.neurol.2013.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 02/28/2013] [Indexed: 12/01/2022]
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Cabianca DS, Casa V, Gabellini D. A novel molecular mechanism in human genetic disease: a DNA repeat-derived lncRNA. RNA Biol 2012; 9:1211-7. [PMID: 23047063 DOI: 10.4161/rna.21922] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Two thirds of the human genome is composed of repetitive sequences. Despite their prevalence, DNA repeats are largely ignored. The vast majority of our genome is transcribed to produce non protein-coding RNAs. Among these, long non protein-coding RNAs represent the most prevalent and functionally diverse class. The relevance of the non protein-coding genome to human disease has mainly been studied regarding the altered microRNA expression and function in human cancer. On the contrary, the elucidation of the involvement of long non-coding RNAs in disease is only in its infancy. We have recently found that a chromatin associated, long non protein-coding RNA regulates a Polycomb/Trithorax epigenetic switch at the basis of the repeat associated facioscapulohumeral muscular dystrophy, a common muscle disorder. Based on this, we propose that long non-coding RNAs produced by repetitive sequences contribute in shaping the epigenetic landscape in normal human physiology and in disease.
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Affiliation(s)
- Daphne S Cabianca
- Dulbecco Telethon Institute and Division of Regenerative Medicine, Stem cells, and Gene therapy, San Raffaele Scientific Institute, Milan, Italy
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28
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Krom YD, Dumonceaux J, Mamchaoui K, den Hamer B, Mariot V, Negroni E, Geng LN, Martin N, Tawil R, Tapscott SJ, van Engelen BGM, Mouly V, Butler-Browne GS, van der Maarel SM. Generation of isogenic D4Z4 contracted and noncontracted immortal muscle cell clones from a mosaic patient: a cellular model for FSHD. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 181:1387-401. [PMID: 22871573 DOI: 10.1016/j.ajpath.2012.07.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 06/25/2012] [Accepted: 07/02/2012] [Indexed: 01/24/2023]
Abstract
In most cases facioscapulohumeral muscular dystrophy (FSHD) is caused by contraction of the D4Z4 repeat in the 4q subtelomere. This contraction is associated with local chromatin decondensation and derepression of the DUX4 retrogene. Its complex genetic and epigenetic cause and high clinical variability in disease severity complicate investigations on the pathogenic mechanism underlying FSHD. A validated cellular model bypassing the considerable heterogeneity would facilitate mechanistic and therapeutic studies of FSHD. Taking advantage of the high incidence of somatic mosaicism for D4Z4 repeat contraction in de novo FSHD, we have established a clonal myogenic cell model from a mosaic patient. Individual clones are genetically identical except for the size of the D4Z4 repeat array, being either normal or FSHD sized. These clones retain their myogenic characteristics, and D4Z4 contracted clones differ from the noncontracted clones by the bursts of expression of DUX4 in sporadic nuclei, showing that this burst-like phenomenon is a locus-intrinsic feature. Consequently, downstream effects of DUX4 expression can be observed in D4Z4 contracted clones, like differential expression of DUX4 target genes. We also show their participation to in vivo regeneration with immunodeficient mice, further expanding the potential of these clones for mechanistic and therapeutic studies. These cell lines will facilitate pairwise comparisons to identify FSHD-specific differences and are expected to create new opportunities for high-throughput drug screens.
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Affiliation(s)
- Yvonne D Krom
- Leiden University Medical Center, Leiden, The Netherlands
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29
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Cabianca DS, Casa V, Bodega B, Xynos A, Ginelli E, Tanaka Y, Gabellini D. A long ncRNA links copy number variation to a polycomb/trithorax epigenetic switch in FSHD muscular dystrophy. Cell 2012; 149:819-31. [PMID: 22541069 PMCID: PMC3350859 DOI: 10.1016/j.cell.2012.03.035] [Citation(s) in RCA: 284] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 12/21/2011] [Accepted: 03/22/2012] [Indexed: 02/05/2023]
Abstract
Repetitive sequences account for more than 50% of the human genome. Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal-dominant disease associated with reduction in the copy number of the D4Z4 repeat mapping to 4q35. By an unknown mechanism, D4Z4 deletion causes an epigenetic switch leading to de-repression of 4q35 genes. Here we show that the Polycomb group of epigenetic repressors targets D4Z4 in healthy subjects and that D4Z4 deletion is associated with reduced Polycomb silencing in FSHD patients. We identify DBE-T, a chromatin-associated noncoding RNA produced selectively in FSHD patients that coordinates de-repression of 4q35 genes. DBE-T recruits the Trithorax group protein Ash1L to the FSHD locus, driving histone H3 lysine 36 dimethylation, chromatin remodeling, and 4q35 gene transcription. This study provides insights into the biological function of repetitive sequences in regulating gene expression and shows how mutations of such elements can influence the progression of a human genetic disease.
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Affiliation(s)
- Daphne S Cabianca
- Dulbecco Telethon Institute at San Raffaele Scientific Institute, Division of Regenerative Medicine, Stem Cells, and Gene Therapy, Milan, Italy
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30
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Neguembor MV, Gabellini D. In junk we trust: repetitive DNA, epigenetics and facioscapulohumeral muscular dystrophy. Epigenomics 2012; 2:271-87. [PMID: 22121874 DOI: 10.2217/epi.10.8] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant myopathy with a peculiar etiology. Unlike most genetic disorders, FSHD is not caused by mutations in a protein-coding gene. Instead, it is associated with contraction of the D4Z4 macrosatellite repeat array located at 4q35. Interestingly, D4Z4 deletion is not sufficient per se to cause FSHD. Moreover, the disease severity, its rate of progression and the distribution of muscle weakness display great variability even among close family relatives. Hence, additional genetic and epigenetic events appear to be required for FSHD pathogenesis. Indeed, recent findings suggest that virtually all levels of epigenetic regulation, from DNA methylation to higher order chromosomal architecture, exhibit alterations in the disease locus causing deregulation of 4q35 gene expression, ultimately leading to FSHD.
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Affiliation(s)
- Maria V Neguembor
- International PhD Program in Cellular & Molecular Biology, Vita-Salute San Raffaele University, Milan, Italy
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31
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Jordan B, Müller-Reible C, Zierz S. [Facioscapulohumeral muscular dystrophy. Clinical picture, atypical forms, diagnostics, genetics]. DER NERVENARZT 2012; 82:712-22. [PMID: 21567298 DOI: 10.1007/s00115-010-2968-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The classic phenotype of the facioscapulohumeral muscular dystrophy (FSHD) includes an initially restricted pattern of asymmetric weakness of facial and shoulder girdle muscles. Disease progression is usually slow and typically accompanied by foot extensor muscle weakness and pelvic girdle weakness. Atypical patterns of FSHD that include isolated camptocormia and facial muscle sparing exceed current diagnostic criteria. No causal genetic lesion in FSHD has been identified yet. In the vast majority of cases, FSHD results from a heterozygous partial deletion of a critical number of repetitive elements (D4Z4) on chromosome 4q35 (4qA allele). Molecular diagnostic testing is appropriate to confirm the diagnosis of FSHD without need for muscle biopsy. Penetrance of this dominantly inherited disorder is high, exhibiting a great phenotypic variability in clinical pattern and disease progression even among affected members of the same family.
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Affiliation(s)
- B Jordan
- Klinik für Neurologie, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale.
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Nguyen K, Walrafen P, Bernard R, Attarian S, Chaix C, Vovan C, Renard E, Dufrane N, Pouget J, Vannier A, Bensimon A, Lévy N. Molecular combing reveals allelic combinations in facioscapulohumeral dystrophy. Ann Neurol 2012; 70:627-33. [PMID: 22028222 DOI: 10.1002/ana.22513] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The genetic variation underlying facioscapulohumeral muscular dystrophy (FSHD), 1 of the most common hereditary neuromuscular disorders, is complex, and associated with the contraction of a repeat array (D4Z4) at the subtelomeric end of chromosome 4q. Nonpathogenic variants of 4q and the presence of a homologous array on chromosome 10q make FSHD diagnosis extremely challenging, at least in individuals with nonstandard D4Z4 arrays. We aimed to improve FSHD molecular analysis by proposing an alternative technique to the Southern blot. METHODS We applied molecular combing (MC) to directly visualize allelic combinations associated with FSHD. RESULTS MC enabled the accurate diagnosis of 32 FSHD patients. Unreported haplotypes and rearrangements, as well as somatic mosaicism, which is common in the 10 to 30% of cases that are sporadic, were detectable by MC. INTERPRETATION MC enables the detailed exploration of the FSHD locus and accurate diagnosis of FSHD, the first Mendelian disease to benefit from this technique. MC is also likely to be applicable to other copy number-variant or repeat expansion-associated human diseases.
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Affiliation(s)
- Karine Nguyen
- Assistance Publique-Hôpitaux de Marseille, Department of Medical Genetics, Timone Children's Hospital, Marseille, France
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Lemmers RJLF, O'Shea S, Padberg GW, Lunt PW, van der Maarel SM. Best practice guidelines on genetic diagnostics of Facioscapulohumeral muscular dystrophy: workshop 9th June 2010, LUMC, Leiden, The Netherlands. Neuromuscul Disord 2011; 22:463-70. [PMID: 22177830 DOI: 10.1016/j.nmd.2011.09.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2011] [Revised: 08/16/2011] [Accepted: 09/07/2011] [Indexed: 12/18/2022]
Affiliation(s)
- Richard J L F Lemmers
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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Genetic counseling and testing for FSHD (facioscapulohumeral muscular dystrophy) in the Israeli population. J Genet Couns 2011; 21:557-63. [PMID: 22109111 DOI: 10.1007/s10897-011-9422-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2011] [Accepted: 10/20/2011] [Indexed: 10/15/2022]
Abstract
Facioscapulohumeral muscular dystrophy (FSHD), is a dominantly inherited, late onset, progressive disease. At present, no treatment or prevention of symptoms are available. There is considerable clinical variability, even within families. The gene whose defect causes FSHD has not been identified, but molecular diagnosis can be made by analyzing D4Z4 repeat length on chromosome 4q35. The results can support or rule out the clinical diagnosis of FSHD, but there are also "gray zone", non-conclusive results. During the years 2000-6, 66 individuals (including 7 asymptomatic individuals), were tested in our institute for D4Z4 repeat number. In 77% of the cases the results were conclusive: two thirds of them supported a diagnosis of FSHD while in a third this diagnosis was ruled out. In 23% the results were in the gray zone. Cognitive involvement was rare, occurring only when the D4Z4 repeat size was very small (<15 kb). Maximal utilization of the existing molecular test for FSHD demands detailed clinical and family pedigree information. We recommend that comprehensive genetic counseling always be given before and after molecular testing for FSHD, in addition to the neurological follow-up. Presymptomatic testing should only be offered when complete molecular evaluation can be offered, including 4qA and 4qB variant analysis.
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Sacconi S, Camaño P, de Greef JC, Lemmers RJLF, Salviati L, Boileau P, Lopez de Munain Arregui A, van der Maarel SM, Desnuelle C. Patients with a phenotype consistent with facioscapulohumeral muscular dystrophy display genetic and epigenetic heterogeneity. J Med Genet 2011; 49:41-6. [PMID: 21984748 DOI: 10.1136/jmedgenet-2011-100101] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE To identify the genetic and epigenetic defects in patients presenting with a facioscapulohumeral (FSHD) clinical phenotype without D4Z4 contractions on chromosome 4q35 tested by linear gel electrophoresis and Southern blot analysis. DESIGN AND PATIENTS The authors studied 16 patients displaying an FSHD-like phenotype, with normal cardiovascular and respiratory function, a myopathic pattern on electromyography, and a muscle biopsy being normal or displaying only mild and aspecific dystrophic changes. They sequenced the genes calpain 3 (CAPN3), valosin containing protein (VCP) and four-and-a-half LIM domains protein 1 (FHL1), and they analysed the D4Z4 repeat arrays by extensive genotyping and DNA methylation analysis. RESULTS The authors identified one patient carrying a complex rearrangement in the FSHD locus that masked the D4Z4 contraction associated with FSHD1 in standard genetic testing, one patient with somatic mosaicism for the D4Z4 4q35 contraction, six patients that were diagnosed as having FSHD2, four patients with CAPN3 mutations and two patients with a VCP mutation, No mutations were detected in FHL1, and in two patients, the authors could not identify the genetic defect. CONCLUSIONS In patients presenting with an FSHD-like clinical phenotype with a negative molecular testing for FSHD, consider (1) detailed genetic testing including D4Z4 contraction of permissive hybrid D4Z4 repeat arrays, p13E-11 probe deletions, and D4Z4 hypomethylation in the absence of repeat contraction as observed in FSHD2; (2) mutations in CAPN3 even in the absence of protein deficiency on western blot analysis; and (3) VCP mutations even in the absence of cognitive impairment, Paget disease and typical inclusion in muscle biopsy.
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Affiliation(s)
- Sabrina Sacconi
- Centre de référence des Maladies neuromusculaires and CNRS UMR6543, Nice University Hospital, Nice, France.
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Grosso S, Mostardini R, Di Bartolo RM, Balestri P, Verrotti A. Epilepsy, speech delay, and mental retardation in facioscapulohumeral muscular dystrophy. Eur J Paediatr Neurol 2011; 15:456-60. [PMID: 21763164 DOI: 10.1016/j.ejpn.2011.04.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 03/04/2011] [Accepted: 04/16/2011] [Indexed: 12/12/2022]
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common muscular dystrophies which is related to the deletion of tandem repeats on chromosome 4q35. Extramuscular features such as hearing loss, retinopathy, mental retardation, and epilepsy, may be observed in patients carrying large 4q35 deletions resulting in fragment sizes less than 12 kilobases (kb) (normal >35 kb). We report on a family affected by FSHD carrying a small 4q35 deletion and residual fragments length of 17 kb, presenting with epilepsy (three patients), speech delay (two), and mental retardation (one). In all patients semeiology of seizures and interictal EEG anomalies were congruent with a localization-related epilepsy possibly involving the temporal lobe. In conclusion, we provide further evidences that extramuscular findings such as epilepsy, speech delay, and mental retardation may occur in those patients carrying smaller 4q35 deletions, suggesting that a close correlation between 4q35 fragment size and clinical severity in FSHD is therefore not constant. Moreover, a review of the literature and our observations seem to suggest that focal epilepsies, likely related to the temporal lobe in the present family, represent the main type of epilepsy occurring in children with FSHD.
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Affiliation(s)
- Salvatore Grosso
- Department of Pediatrics, Gynecology, Obstetrics, and Reproductive Medicine, Pediatric Neurology Section, University of Siena, Italy.
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Distrofia muscolare facio-scapolo-omerale. Neurologia 2011. [DOI: 10.1016/s1634-7072(11)70626-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
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Orrell RW. Facioscapulohumeral dystrophy and scapuloperoneal syndromes. HANDBOOK OF CLINICAL NEUROLOGY 2011; 101:167-80. [PMID: 21496633 DOI: 10.1016/b978-0-08-045031-5.00013-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Facioscapulohumeral dystrophy (FSHD) is the third most common muscular dystrophy. It is named for its characteristic involvement of the muscles of the face and upper arm. It is present worldwide, with a prevalence of around 4 per 100000 and an incidence of about 1 in 20000. Overall lifespan is not affected significantly. The scapuloperoneal syndrome is a rarer presentation that may cause some confusion. FSHD is an autosomal dominant condition. The molecular genetics of FSHD are complex, with current understanding focusing on epigenetic effects related to contraction-dependent (FSHD1) and contraction-independent (FSHD2) effects of a hypomethylated repeat sequence (D4Z4), in the presence of a specific 4qA161 phenotype. Molecular genetic diagnosis is available based on these findings, but with some complexities which may lead to false-negative results on routine laboratory investigation. No medication has been demonstrated to alter the clinical course of the disease significantly. A range of supportive measures may be applied. This chapter reviews the epidemiology, pathogenesis, genetics, clinical features, investigation, prognosis, and management of patients with FSHD and the scapuloperoneal syndrome.
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Affiliation(s)
- Richard W Orrell
- University Department of Clinical Neurosciences, UCL Institute of Neurology, London, UK
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Cabianca DS, Gabellini D. The cell biology of disease: FSHD: copy number variations on the theme of muscular dystrophy. J Cell Biol 2010; 191:1049-60. [PMID: 21149563 PMCID: PMC3002039 DOI: 10.1083/jcb.201007028] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Accepted: 11/08/2010] [Indexed: 01/17/2023] Open
Abstract
In humans, copy number variations (CNVs) are a common source of phenotypic diversity and disease susceptibility. Facioscapulohumeral muscular dystrophy (FSHD) is an important genetic disease caused by CNVs. It is an autosomal-dominant myopathy caused by a reduction in the copy number of the D4Z4 macrosatellite repeat located at chromosome 4q35. Interestingly, the reduction of D4Z4 copy number is not sufficient by itself to cause FSHD. A number of epigenetic events appear to affect the severity of the disease, its rate of progression, and the distribution of muscle weakness. Indeed, recent findings suggest that virtually all levels of epigenetic regulation, from DNA methylation to higher order chromosomal architecture, are altered at the disease locus, causing the de-regulation of 4q35 gene expression and ultimately FSHD.
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Affiliation(s)
- Daphne Selvaggia Cabianca
- International PhD Program in Cellular and Molecular Biology, Vita-Salute San Raffaele University, 20132 Milan, Italy
- Division of Regenerative Medicine, San Raffaele Scientific Institute, DIBIT 1, 2A3-49, 20132 Milan, Italy
| | - Davide Gabellini
- Division of Regenerative Medicine, San Raffaele Scientific Institute, DIBIT 1, 2A3-49, 20132 Milan, Italy
- Dulbecco Telethon Institute, 20132 Milan, Italy
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Wang ZQ, Wang N, van der Maarel S, Murong SX, Wu ZY. Distinguishing the 4qA and 4qB variants is essential for the diagnosis of facioscapulohumeral muscular dystrophy in the Chinese population. Eur J Hum Genet 2010; 19:64-9. [PMID: 20736973 DOI: 10.1038/ejhg.2010.143] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is the third most common inherited muscular dystrophy with markedly clinical variability and complex genetic cause. Several reports pertaining to the Caucasian population have confirmed that there are 4qA and 4qB variants of the 4qter subtelomere, and FSHD is uniquely associated with the 4qA variant. However, few data relevant to the Chinese population have been published. In present paper, detailed clinical and genetic re-evaluations were performed in members of four special families who had been initially diagnosed as atypical or asymptomatic FSHD based only on the D4Z4 repeat length analysis. The FSHD-sized D4Z4 repeats in the probands from families 1, 2 and 3 were identified as 4qB variants. These patients were further confirmed as limb-girdle muscular dystrophy (LGMD2) or myotonic dystrophy (DM1) by molecular analyses. Specifically, we identified a 4qB variant on chromosome 10 in the healthy members of the fourth FSHD family with complex D4Z4 rearrangements of two exchanged repeat arrays. For the first time, we demonstrated in the Chinese population that D4Z4 contractions on the 4qB variant do not cause FSHD and 4qB variant on chromosome 10 might also represent intermediate structures in the transition from 4q to 10q. Furthermore, our results emphasize that D4Z4 repeat length analysis alone is not sufficient for the diagnosis of FSHD, especially when used as an exclusion criterion. This analysis should be accompanied by 4qA/4qB variant determination and integrated chromosome assignments, especially in patients with obscure and unclassified myopathies similar to atypical forms of FSHD.
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Affiliation(s)
- Zhi-Qiang Wang
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Center of Neuroscience, Fujian Medical University, Fuzhou, China
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Tsumagari K, Chen D, Hackman JR, Bossler AD, Ehrlich M. FSH dystrophy and a subtelomeric 4q haplotype: a new assay and associations with disease. J Med Genet 2010; 47:745-51. [PMID: 20710047 DOI: 10.1136/jmg.2009.076703] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
BACKGROUND Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant disease associated with contraction of arrays of tandem 3.3-kb units (D4Z4) on subtelomeric 4q. Disease-linked arrays usually have fewer than 11 repeat units. Equally short D4Z4 arrays at subtelomeric 10q are not linked to FSHD. The newly described 4qA161 haplotype, which is more prevalent in pathogenic 4q alleles, involves sequences in and near D4Z4. METHODS We developed two new assays for 4qA161, which are based upon direct sequencing of PCR products or detecting restriction fragment length polymorphisms. They were used to analyse single nucleotide polymorphisms (SNPs) indicative of 4q161 alleles. RESULTS All (35/35) FSHD patients had one or two 4qA161 alleles (60% or 40%, respectively). In contrast, 46% (21/46) of control individuals had no 4qA161 allele (p<10(-4)), and 26% had homozygous 4qB163 alleles. CONCLUSIONS Our results from a heterogeneous population are consistent with the previously described association of the 4qA161 haplotype with FSHD, but a causal association with pathogenesis is uncertain. In addition, we found that haplotype analysis is complicated by the presence of minor 10q alleles. Nonetheless, our sequencing assay for the 4qA161allele can enhance molecular diagnosis of FSHD, including prenatal diagnosis, and is simpler to perform than the previously described assay.
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Affiliation(s)
- K Tsumagari
- Biochemistry Department, Tulane Medical School, New Orleans, Louisiana, USA
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Barat-Houari M, Nguyen K, Bernard R, Fernandez C, Vovan C, Bareil C, Khau Van Kien P, Thorel D, Tuffery-Giraud S, Vasseur F, Attarian S, Pouget J, Girardet A, Lévy N, Claustres M. New multiplex PCR-based protocol allowing indirect diagnosis of FSHD on single cells: can PGD be offered despite high risk of recombination? Eur J Hum Genet 2010; 18:533-8. [PMID: 19935833 PMCID: PMC2987324 DOI: 10.1038/ejhg.2009.207] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 10/01/2009] [Accepted: 10/14/2009] [Indexed: 01/23/2023] Open
Abstract
Molecular pathophysiology of facioscapulohumeral muscular dystrophy (FSHD) involves the heterozygous contraction of the number of tandemly repeated D4Z4 units at chromosome 4q35.2. FSHD is associated with a range of 1-10 D4Z4 units instead of 11-150 in normal controls. Several factors complicate FSHD molecular diagnosis, especially the cis-segregation of D4Z4 contraction with a 4qA allele, whereas D4Z4 shortening is silent both on alleles 4qB and 10q. Discrimination of pathogenic 4q-D4Z4 alleles from highly homologous 10q-D4Z4 arrays requires the use of the conventional Southern blot, which is not suitable at the single-cell level. Preimplantation genetic diagnosis (PGD) is a frequent request from FSHD families with several affected relatives. We aimed to develop a rapid and sensitive PCR-based multiplex approach on single cells to perform an indirect familial segregation study of pathogenic alleles. Among several available polymorphic markers at 4q35.2, the four most proximal (D4S2390, D4S1652, D4S2930 and D4S1523, <1.23 Mb) showing the highest heterozygote frequencies (67-91%) were selected. Five recombination events in the D4S2390-D4S1523 interval were observed among 144 meioses. In the D4S2390-D4Z4 interval, no recombination event occurred among 28 FSHD meioses. Instead, a particular haplotype segregated with both clinical and molecular status, allowing the characterization of an at-risk allele in each tested FSHD family (maximal LOD score 2.98 for theta=0.0). This indirect protocol can easily complement conventional techniques in prenatal diagnosis. Although our multiplex PCR-based approach technically fulfils guidelines for single-cell analysis, the relatively high recombination risk hampers its application to PGD.
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Affiliation(s)
- Mouna Barat-Houari
- CHU de Montpellier, Laboratoire de Génétique Moléculaire, Montpellier, France.
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Focal segmental glomerulosclerosis, Coats'-like retinopathy, sensorineural deafness and chromosome 4 duplication: a new association. Pediatr Nephrol 2010; 25:1551-4. [PMID: 20191367 PMCID: PMC2887537 DOI: 10.1007/s00467-010-1474-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 01/11/2010] [Accepted: 01/12/2010] [Indexed: 11/15/2022]
Abstract
We describe the novel association in a girl of nephrotic syndrome due to focal segmental glomerulosclerosis, bilateral sensorineural deafness, basal ganglia calcification, bilateral retinopathy similar to that seen in Coats' disease, with de novo duplication of a subtelomeric region of chromosome 4q35. The chromosomal duplication was identified during investigation of a possible association with features of fascio-scapulo-humeral dystrophy (FSHD). This duplication has not previously been reported with FSGS and adds to the expanding number of genetic associations with steroid-resistant nephrotic syndrome.
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Klooster R, Straasheijm K, Shah B, Sowden J, Frants R, Thornton C, Tawil R, van der Maarel S. Comprehensive expression analysis of FSHD candidate genes at the mRNA and protein level. Eur J Hum Genet 2009; 17:1615-24. [PMID: 19809486 PMCID: PMC2987013 DOI: 10.1038/ejhg.2009.62] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 03/18/2009] [Accepted: 03/18/2009] [Indexed: 01/24/2023] Open
Abstract
In facioscapulohumeral muscular dystrophy (FSHD) the majority of patients carry a D4Z4 macrosatellite repeat contraction in the subtelomere of chromosome 4q. Several disease mechanisms have been proposed to explain how repeat contraction causes muscular dystrophy. All proposed mechanisms foresee a change from a closed to a more open chromatin structure followed by loss of control over expression of genes in or proximal to D4Z4. Initially, a distance and residual repeat size-dependent upregulation of the candidate genes FRG2, FRG1 and ANT1 was observed, but most successive expression studies failed to support transcriptional upregulation of 4qter genes. Moreover, chromatin studies do not provide evidence for a cis-spreading mechanism operating at 4qter in FSHD. In part, this inconsistency may be explained by differences in the techniques used, and the use of RNA samples obtained from different muscle groups. The aim of this study is to comprehensively and uniformly study the expression of the FSHD candidate genes FRG1, FRG2, CRYM, ANT1, ALP, PITX1 and LRP2BP at the RNA and protein level in identically processed primary myoblasts, myotubes and quadriceps muscle. Expression was compared between samples obtained from FSHD patients and normal controls with samples from myotonic dystrophy type 1 patients as disease controls. No consistent changes in RNA or protein expression levels were observed between the samples. The one exception was a selective increase in FRG2 mRNA expression in FSHD myotubes. This study provides further evidence that there is no demonstrable consistent, large magnitude, overexpression of any of the FSHD candidate genes.
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Affiliation(s)
- Rinse Klooster
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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Ansseau E, Laoudj-Chenivesse D, Marcowycz A, Tassin A, Vanderplanck C, Sauvage S, Barro M, Mahieu I, Leroy A, Leclercq I, Mainfroid V, Figlewicz D, Mouly V, Butler-Browne G, Belayew A, Coppée F. DUX4c is up-regulated in FSHD. It induces the MYF5 protein and human myoblast proliferation. PLoS One 2009; 4:e7482. [PMID: 19829708 PMCID: PMC2759506 DOI: 10.1371/journal.pone.0007482] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Accepted: 09/17/2009] [Indexed: 12/21/2022] Open
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is a dominant disease linked to contractions of the D4Z4 repeat array in 4q35. We have previously identified a double homeobox gene (DUX4) within each D4Z4 unit that encodes a transcription factor expressed in FSHD but not control myoblasts. DUX4 and its target genes contribute to the global dysregulation of gene expression observed in FSHD. We have now characterized the homologous DUX4c gene mapped 42 kb centromeric of the D4Z4 repeat array. It encodes a 47-kDa protein with a double homeodomain identical to DUX4 but divergent in the carboxyl-terminal region. DUX4c was detected in primary myoblast extracts by Western blot with a specific antiserum, and was induced upon differentiation. The protein was increased about 2-fold in FSHD versus control myotubes but reached 2-10-fold induction in FSHD muscle biopsies. We have shown by Western blot and by a DNA-binding assay that DUX4c over-expression induced the MYF5 myogenic regulator and its DNA-binding activity. DUX4c might stabilize the MYF5 protein as we detected their interaction by co-immunoprecipitation. In keeping with the known role of Myf5 in myoblast accumulation during mouse muscle regeneration DUX4c over-expression activated proliferation of human primary myoblasts and inhibited their differentiation. Altogether, these results suggested that DUX4c could be involved in muscle regeneration and that changes in its expression could contribute to the FSHD pathology.
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Affiliation(s)
- Eugénie Ansseau
- Laboratory of Molecular Biology, University of Mons-Hainaut, 6, Mons, Belgium
| | | | - Aline Marcowycz
- Laboratory of Molecular Biology, University of Mons-Hainaut, 6, Mons, Belgium
| | - Alexandra Tassin
- Laboratory of Molecular Biology, University of Mons-Hainaut, 6, Mons, Belgium
| | - Céline Vanderplanck
- Laboratory of Molecular Biology, University of Mons-Hainaut, 6, Mons, Belgium
| | - Sébastien Sauvage
- Laboratory of Molecular Biology, University of Mons-Hainaut, 6, Mons, Belgium
| | - Marietta Barro
- INSERM ERI 25 Muscle et Pathologies, CHU A. de Villeneuve, Montpellier, France
| | - Isabelle Mahieu
- Laboratory of Molecular Biology, University of Mons-Hainaut, 6, Mons, Belgium
| | - Axelle Leroy
- Laboratory of Molecular Biology, University of Mons-Hainaut, 6, Mons, Belgium
| | - India Leclercq
- Laboratory of Molecular Biology, University of Mons-Hainaut, 6, Mons, Belgium
| | | | - Denise Figlewicz
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Vincent Mouly
- Institute of Myology, Platform for human cell culture, Paris, France
| | | | - Alexandra Belayew
- Laboratory of Molecular Biology, University of Mons-Hainaut, 6, Mons, Belgium
| | - Frédérique Coppée
- Laboratory of Molecular Biology, University of Mons-Hainaut, 6, Mons, Belgium
- * E-mail:
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Dmitriev P, Lipinski M, Vassetzky YS. Pearls in the junk: Dissecting the molecular pathogenesis of facioscapulohumeral muscular dystrophy. Neuromuscul Disord 2009; 19:17-20. [DOI: 10.1016/j.nmd.2008.09.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Revised: 09/08/2008] [Accepted: 09/09/2008] [Indexed: 11/16/2022]
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de Greef JC, Frants RR, van der Maarel SM. Epigenetic mechanisms of facioscapulohumeral muscular dystrophy. Mutat Res 2008; 647:94-102. [PMID: 18723032 PMCID: PMC2650037 DOI: 10.1016/j.mrfmmm.2008.07.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 07/18/2008] [Accepted: 07/23/2008] [Indexed: 04/08/2023]
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) seems to be caused by a complex epigenetic disease mechanism as a result of contraction of the polymorphic macrosatellite repeat D4Z4 on chromosome 4qter. Currently, the exact mechanism causing the FSHD phenotype is still not elucidated. In this review, we discuss the genetic and epigenetic changes observed in patients with FSHD and the possible disease mechanisms that may be associated with FSHD pathogenesis.
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Affiliation(s)
- Jessica C. de Greef
- Department of Human Genetics, Leiden University Medical Center (LUMC), Leiden, The Netherlands
| | - Rune R. Frants
- Department of Human Genetics, Leiden University Medical Center (LUMC), Leiden, The Netherlands
| | - Silvère M. van der Maarel
- Department of Human Genetics, Leiden University Medical Center (LUMC), Leiden, The Netherlands
- Address correspondence and reprint requests to: Dr. S.M. van der Maarel, Department of Human Genetics, Center for Human and Clinical Genetics, Leiden University Medical Center, Bldg. 2, room S-03-042, Postal zone S-4-P, P.O. Box 9600, 2300 RC Leiden, The Netherlands
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Tsumagari K, Qi L, Jackson K, Shao C, Lacey M, Sowden J, Tawil R, Vedanarayanan V, Ehrlich M. Epigenetics of a tandem DNA repeat: chromatin DNaseI sensitivity and opposite methylation changes in cancers. Nucleic Acids Res 2008; 36:2196-207. [PMID: 18281700 PMCID: PMC2367708 DOI: 10.1093/nar/gkn055] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
DNA methylation and chromatin DNaseI sensitivity were analyzed in and adjacent to D4Z4 repeat arrays, which consist of 1 to ∼100 tandem 3.3-kb units at subtelomeric 4q and 10q. D4Z4 displayed hypomethylation in some cancers and hypermethylation in others relative to normal tissues. Surprisingly, in cancers with extensive D4Z4 methylation there was a barrier to hypermethylation spreading to the beginning of this disease-associated array (facioscapulohumeral muscular dystrophy, FSHD) despite sequence conservation in repeat units throughout the array. We infer a different chromatin structure at the proximal end of the array than at interior repeats, consistent with results from chromatin DNaseI sensitivity assays indicating a boundary element near the beginning of the array. The relative chromatin DNaseI sensitivity in FSHD and control myoblasts and lymphoblasts was as follows: a non-genic D4Z4-adjacent sequence (p13E-11, array-proximal)> untranscribed gene standards > D4Z4 arrays> constitutive heterochromatin (satellite 2; P< 10−4 for all comparisons). Cancers displaying D4Z4 hypermethylation also exhibited a hypermethylation-resistant subregion within the 3.3-kb D4Z4 repeat units. This subregion contains runs of G that form G-quadruplexes in vitro. Unusual DNA structures might contribute to topological constraints that link short 4q D4Z4 arrays to FSHD and make long ones phenotypically neutral.
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Affiliation(s)
- Koji Tsumagari
- Human Genetics Program and Department of Biochemistry and Tulane Cancer Center, Tulane Medical School, Department of Mathematics, Tulane University, New Orleans, LA 70112, USA
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Kowaljow V, Marcowycz A, Ansseau E, Conde CB, Sauvage S, Mattéotti C, Arias C, Corona ED, Nuñez NG, Leo O, Wattiez R, Figlewicz D, Laoudj-Chenivesse D, Belayew A, Coppée F, Rosa AL. The DUX4 gene at the FSHD1A locus encodes a pro-apoptotic protein. Neuromuscul Disord 2007; 17:611-23. [PMID: 17588759 DOI: 10.1016/j.nmd.2007.04.002] [Citation(s) in RCA: 248] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2007] [Revised: 03/28/2007] [Accepted: 04/05/2007] [Indexed: 12/19/2022]
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) patients carry contractions of the D4Z4-tandem repeat array on chromosome 4q35. Decrease in D4Z4 copy number is thought to alter a chromatin structure and activate expression of neighboring genes. D4Z4 contains a putative double-homeobox gene called DUX4. We identified DUX4 mRNAs in cells transfected with genomic fragments containing the DUX4 gene. Using RT-PCR we also recognized expressed DUX4 mRNAs in primary FSHD myoblasts. Polyclonal antibodies raised against specific DUX4 peptides detected the DUX4 protein in cells transfected with D4Z4 elements. DUX4 localizes in the nucleus of cells transfected with CMV-DUX4 expression vectors. A DUX4-related protein is endogenously expressed in nuclei of adult and fetal human rhabdomyosarcoma cell lines. Overexpression of DUX4 induces cell death, induces caspase 3/7 activity and alters emerin distribution at the nuclear envelope. We propose that DUX4-mediated cell death contributes to the pathogenic pathway in FSHD.
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Affiliation(s)
- Valeria Kowaljow
- Laboratorio de Neurogenética, Instituto de Investigación, Médica Mercedes y Martín Ferreyra (INIMEC-CONICET), Córdoba, Argentina
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Ehrlich M, Jackson K, Tsumagari K, Camaño P, Lemmers RJFL. Hybridization analysis of D4Z4 repeat arrays linked to FSHD. Chromosoma 2006; 116:107-16. [PMID: 17131163 PMCID: PMC1828046 DOI: 10.1007/s00412-006-0080-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2006] [Revised: 08/18/2006] [Accepted: 08/22/2006] [Indexed: 12/12/2022]
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant disease involving shortening of D4Z4, an array of tandem 3.3-kb repeat units on chromosome 4. These arrays are in subtelomeric regions of 4q and 10q and have 1-100 units. FSHD is associated with an array of 1-10 units at 4q35. Unambiguous clinical diagnosis of FSHD depends on determining the array length at 4q35, usually with the array-adjacent p13E-11 probe after pulsed-field or linear gel electrophoresis. Complicating factors for molecular diagnosis of FSHD are the phenotypically neutral 10q D4Z4 arrays, cross-hybridizing sequences elsewhere in the genome, deletions including the genomic p13E-11 sequence and part of D4Z4, translocations between 4q and 10q D4Z4 arrays, and the extremely high G + C content of D4Z4 arrays (73%). In this study, we optimized conditions for molecular diagnosis of FSHD with a 1-kb D4Z4 subfragment probe after hybridization with p13E-11. We demonstrate that these hybridization conditions allow the identification of FSHD alleles with deletions of the genomic p13E-11 sequence and aid in determination of the nonpathogenic D4Z4 arrays at 10q. Furthermore, we show that the D4Z4-like sequences present elsewhere in the genome are not tandemly arranged, like those at 4q35 and 10q26.
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Affiliation(s)
- Melanie Ehrlich
- Program in Human Genetics and Department of Biochemistry, Tulane Medical School, New Orleans, LA, USA.
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