Publications by authors named "Rossella Tupler"

39 Publications

Increased resistance towards fatigability in patients with facioscapulohumeral muscular dystrophy.

Eur J Appl Physiol 2021 Mar 1. Epub 2021 Mar 1.

Criams-Sport Medicine Centre Voghera, University of Pavia, Voghera, Italy.

Purpose: In facioscapulohumeral muscular dystrophy (FSHD) fatigue is a major complaint. We aimed to investigate whether during isometric sustained elbow flexions, performance fatigability indexes differ in patients with FSHD with respect to healthy controls.

Methods: Seventeen patients with FSHD and seventeen healthy controls performed two isometric flexions of the dominant biceps brachii at 20% of their maximal voluntary contraction (MVC) for 2 min and then at 60% MVC until exhaustion. Muscle weakness was characterized as a percentage of predicted values. Maximal voluntary strength, endurance time and performance fatigability indices (mean frequency of the power spectrum (MNF), muscle fiber conduction velocity (CV) and fractal dimension (FD)), extracted from the surface electromyogram signal (sEMG) were compared between the two groups.

Results: In patients with FSHD, maximal voluntary strength was 68.7% of predicted value (p < 0.01). Compared to healthy controls, FSHD patients showed reduced MVC (p < 0.001; r = 0.62) and lower levels of performance fatigability, characterized by reduced rate of changes in MNF (p < 0.01; r = 0.56), CV (p < 0.05; 0.37) and FD (p < 0.001; r = 0.51) and increased endurance time (p < 0.001; r = 0.63), during the isometric contraction at 60% MVC.

Conclusion: A decreased reduction in the slopes of all the considered sEMG parameters during sustained isometric elbow flexions suggests that patients with FSHD experience lower levels of performance fatigability compared to healthy controls.
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http://dx.doi.org/10.1007/s00421-021-04650-3DOI Listing
March 2021

Large genotype-phenotype study in carriers of D4Z4 borderline alleles provides guidance for facioscapulohumeral muscular dystrophy diagnosis.

Sci Rep 2020 12 10;10(1):21648. Epub 2020 Dec 10.

Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.

Facioscapulohumeral muscular dystrophy (FSHD) is a myopathy with prevalence of 1 in 20,000. Almost all patients affected by FSHD carry deletions of an integral number of tandem 3.3 kilobase repeats, termed D4Z4, located on chromosome 4q35. Assessment of size of D4Z4 alleles is commonly used for FSHD diagnosis. However, the extended molecular testing has expanded the spectrum of clinical phenotypes. In particular, D4Z4 alleles with 9-10 repeat have been found in healthy individuals, in subjects with FSHD or affected by other myopathies. These findings weakened the strict relationship between observed phenotypes and their underlying genotypes, complicating the interpretation of molecular findings for diagnosis and genetic counseling. In light of the wide clinical variability detected in carriers of D4Z4 alleles with 9-10 repeats, we applied a standardized methodology, the Comprehensive Clinical Evaluation Form (CCEF), to describe and characterize the phenotype of 244 individuals carrying D4Z4 alleles with 9-10 repeats (134 index cases and 110 relatives). The study shows that 54.5% of index cases display a classical FSHD phenotype with typical facial and scapular muscle weakness, whereas 20.1% present incomplete phenotype with facial weakness or scapular girdle weakness, 6.7% display minor signs such as winged scapula or hyperCKemia, without functional motor impairment, and 18.7% of index cases show more complex phenotypes with atypical clinical features. Family studies revealed that 70.9% of relatives carrying 9-10 D4Z4 reduced alleles has no motor impairment, whereas a few relatives (10.0%) display a classical FSHD phenotype. Importantly all relatives of index cases with no FSHD phenotype were healthy carriers. These data establish the low penetrance of D4Z4 alleles with 9-10 repeats. We recommend the use of CCEF for the standardized clinical assessment integrated by family studies and further molecular investigation for appropriate diagnosis and genetic counseling. Especially in presence of atypical phenotypes and/or sporadic cases with all healthy relatives is not possible to perform conclusive diagnosis of FSHD, but all these cases need further studies for a proper diagnosis, to search novel causative genetic defects or investigate environmental factors or co-morbidities that may trigger the pathogenic process. These evidences are also fundamental for the stratification of patients eligible for clinical trials. Our work reinforces the value of large genotype-phenotype studies to define criteria for clinical practice and genetic counseling in rare diseases.
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http://dx.doi.org/10.1038/s41598-020-78578-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7730397PMC
December 2020

Cochlear Dysfunction Is a Frequent Feature of Facioscapulohumeral Muscular Dystrophy Type 1 (FSHD1).

Otol Neurotol 2021 Jan;42(1):18-23

Department of Systems Medicine, Neuromuscular Diseases Unit.

Introduction: Facioscapulohumeral muscular dystrophy type 1 (FSHD) represents one of the most common forms of muscular hereditary diseases and it is characterized by a great clinical variability with the typical muscular symptoms and other clinical features, including hearing impairment. However, etiopathogenetic mechanisms of auditory dysfunction are still not completely understood and it has been suggested that it could be assigned to a cochlear alteration that is present even in those subjects with a normal pure tonal audiometry (PTA) examination.

Methods: We found out the cochlear function in 26 patients with molecular diagnosis of FSHD1 and in healthy controls. All patients underwent complete neurological and audiological examinations, including FSHD clinical score, pure-tone audiometry (PTA), and otoacoustic emissions (OAEs), in particular transient evoked otoacoustic emissions (TEOAEs) and distortion product evoked otoacoustic emissions (DPOAEs).

Results: All FSHD1 patients showed significantly reduced DPOAEs and TEOAEs, bilaterally and at all frequencies, even when considering only subjects with a normal PTA or a mild muscular involvement (FSHD score ≤ 2). No correlation between OAEs and FSHD clinical score was found.

Discussion: Cochlear echoes represent a sensitive tool in detecting subclinical cochlear dysfunction in FSHD1 even in subjects with normal hearing and/or subtle muscle involvement. Our study is focused on the importance of evaluating the cochlear alteration through OAEs and, in particular, by performing TEOAEs and DPOAEs sequentially, to evaluate more frequent specificities of cochlear dysfunction with a wider spectrum of analysis.
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http://dx.doi.org/10.1097/MAO.0000000000002877DOI Listing
January 2021

Mosaicism in Human Health and Disease.

Annu Rev Genet 2020 11 11;54:487-510. Epub 2020 Sep 11.

Department of Neurology, Kennedy Krieger Institute, Baltimore, Maryland 21205, USA; email:

Mosaicism refers to the occurrence of two or more genomes in an individual derived from a single zygote. Germline mosaicism is a mutation that is limited to the gonads and can be transmitted to offspring. Somatic mosaicism is a postzygotic mutation that occurs in the soma, and it may occur at any developmental stage or in adult tissues. Mosaic variation may be classified in six ways: () germline or somatic origin, () class of DNA mutation (ranging in scale from single base pairs to multiple chromosomes), () developmental context, () body location(s), () functional consequence (including deleterious, neutral, or advantageous), and () additional sources of mosaicism, including mitochondrial heteroplasmy, exogenous DNA sources such as vectors, and epigenetic changes such as imprinting and X-chromosome inactivation. Technological advances, including single-cell and other next-generation sequencing, have facilitated improved sensitivity and specificity to detect mosaicism in a variety of biological contexts.
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http://dx.doi.org/10.1146/annurev-genet-041720-093403DOI Listing
November 2020

A 5-year clinical follow-up study from the Italian National Registry for FSHD.

J Neurol 2021 Jan 19;268(1):356-366. Epub 2020 Aug 19.

Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, via G. Campi 287, 41125, Modena, Italy.

Background: The natural history of facioscapulohumeral muscular dystrophy (FSHD) is undefined.

Methods: An observational cohort study was conducted in 246 FSHD1 patients. We split the analysis between index cases and carrier relatives and we classified all patients using the Comprehensive Clinical Evaluation Form (CCEF). The disease progression was measured as a variation of the FSHD score performed at baseline and at the end of 5-year follow-up (ΔFSHD score).

Findings: Disease worsened in 79.4% (112/141) of index cases versus 38.1% (40/105) of carrier relatives and advanced more rapidly in index cases (ΔFSHD score 2.3 versus 1.2). The 79.1% (38/48) of asymptomatic carriers remained asymptomatic. The highest ΔFSHD score (1.7) was found in subject with facial and scapular weakness at baseline (category A), whereas in subjects with incomplete phenotype (facial or scapular weakness, category B) had lower ΔFSHD score (0.6) p < 0.0001.

Conclusions: The progression of disease is different between index cases and carrier relatives and the assessment of the CCEF categories has strong prognostic effect in FSHD1 patients.
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http://dx.doi.org/10.1007/s00415-020-10144-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7815626PMC
January 2021

Deletion of the Williams Beuren syndrome critical region unmasks facioscapulohumeral muscular dystrophy.

Eur J Paediatr Neurol 2020 Jul 22;27:25-29. Epub 2020 May 22.

Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy; Department of of Molecular, Cell and Cancer Biology, University of Massachsetts Medical School, Worcester, USA. Electronic address:

Among 1339 unrelated cases accrued by the Italian National Registry for facioscapulohumeral muscular dystrophy (FSHD), we found three unrelated cases who presented signs of Williams-Beuren Syndrome (WBS) in early childhood and later developed FSHD. All three cases carry the molecular defects associated with the two disorders. The rarity of WBS and FSHD, 1 in 7500 and 1 in 20,000 respectively, makes a random association of the two diseases unlikely. These cases open novel and unexpected interpretation of genetic findings. The nonrandom association of both FSHD and WBS points at a gene co-expression network providing hints for the identification of modules and functionally enriched pathways in the two conditions.
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http://dx.doi.org/10.1016/j.ejpn.2020.05.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7427329PMC
July 2020

Modulation of Cell Death and Promotion of Chondrogenic Differentiation by Fas/FasL in Human Dental Pulp Stem Cells (hDPSCs).

Front Cell Dev Biol 2020 15;8:279. Epub 2020 May 15.

Department of Surgery, Medicine Dentistry and Morphological Sciences with Interest in Transplant, University of Modena and Reggio Emilia, Modena, Italy.

Human dental pulp stem cells (hDPSCs) are characterized by high proliferation rate, the multi-differentiation ability and, notably, low immunogenicity and immunomodulatory properties exerted through different mechanisms including Fas/FasL pathway. Despite their multipotency, hDPSCs require particular conditions to achieve chondrogenic differentiation. This might be due to the perivascular localization and the expression of angiogenic marker under standard culture conditions. FasL stimulation was able to promote the early induction of chondrogenic commitment and to lead the differentiation at later times. Interestingly, the expression of angiogenic marker was reduced by FasL stimulation without activating the extrinsic apoptotic pathway in standard culture conditions. In conclusion, these findings highlight the peculiar embryological origin of hDPSCs and provide further insights on their biological properties. Therefore, Fas/FasL pathway not only is involved in determining the immunomodulatory properties, but also is implicated in supporting the chondrogenic commitment of hDPSCs.
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http://dx.doi.org/10.3389/fcell.2020.00279DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7242757PMC
May 2020

Phenotypic Variability Among Patients With D4Z4 Reduced Allele Facioscapulohumeral Muscular Dystrophy.

JAMA Netw Open 2020 05 1;3(5):e204040. Epub 2020 May 1.

Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.

Importance: Facioscapulohumeral muscular dystrophy (FSHD) is considered an autosomal dominant disorder, associated with the deletion of tandemly arrayed D4Z4 repetitive elements. The extensive use of molecular analysis of the D4Z4 locus for FSHD diagnosis has revealed wide clinical variability, suggesting that subgroups of patients exist among carriers of the D4Z4 reduced allele (DRA).

Objective: To investigate the clinical expression of FSHD in the genetic subgroup of carriers of a DRA with 7 to 8 repeat units (RUs).

Design, Setting, And Participants: This multicenter cross-sectional study included 422 carriers of DRA with 7 to 8 RUs (187 unrelated probands and 235 relatives) from a consecutive sample of 280 probands and 306 relatives from the Italian National Registry for FSHD collected between 2008 and 2016. Participants were evaluated by the Italian Clinical Network for FSHD, and all clinical and molecular data were collected in the Italian National Registry for FSHD database. Data analysis was conducted from January 2017 to June 2018.

Main Outcomes And Measures: The phenotypic classification of probands and relatives was obtained by applying the Comprehensive Clinical Evaluation Form which classifies patients in the 4 following categories: (1) participants presenting facial and scapular girdle muscle weakness typical of FSHD (category A, subcategories A1-A3), (2) participants with muscle weakness limited to scapular girdle or facial muscles (category B, subcategories B1 and B2), (3) asymptomatic or healthy participants (category C, subcategories C1 and C2), and (4) participants with myopathic phenotypes presenting clinical features not consistent with FSHD canonical phenotype (category D, subcategories D1 and D2).

Results: A total of 187 probands (mean [SD] age at last neurological examination, 53.5 [15.2] years; 103 [55.1%] men) and 235 relatives (mean [SD] age at last neurologic examination, 45.1 [17.0] years; 104 [44.7%] men) with a DRA with 7 to 8 RUs and a molecular diagnosis of FSHD were evaluated. Of 187 probands, 99 (52.9%; 95% CI, 45.7%-60.1%) displayed the classic FSHD phenotype, whereas 86 (47.1%; 95% CI, 39.8%-54.3%) presented incomplete or atypical phenotypes. Of 235 carrier relatives from 106 unrelated families, 124 (52.8%; 95% CI, 46.4%-59.7%) had no motor impairment, whereas a small number (38 [16.2%; 95% CI, 9.8%-23.1%]) displayed the classic FSHD phenotype, and 73 (31.0%; 95% CI, 24.7%-38.0%) presented with incomplete or atypical phenotypes. In 37 of 106 families (34.9%; 95% CI, 25.9%-44.8%), the proband was the only participant presenting with a myopathic phenotype, while only 20 families (18.9%; 95% CI, 11.9%-27.6%) had a member with autosomal dominant FSHD.

Conclusions And Relevance: This study found large phenotypic variability associated with individuals carrying a DRA with 7 to 8 RUs, in contrast to the indication that a positive molecular test is the only determining aspect for FSHD diagnosis. These findings suggest that carriers of a DRA with 7 to 8 RUs constitute a genetic subgroup different from classic FSHD. Based on these results, it is recommended that clinicians use the Comprehensive Clinical Evaluation Form for clinical classification and, whenever possible, study the extended family to provide the most adequate clinical management and genetic counseling.
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http://dx.doi.org/10.1001/jamanetworkopen.2020.4040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7195625PMC
May 2020

Interpretation of the Epigenetic Signature of Facioscapulohumeral Muscular Dystrophy in Light of Genotype-Phenotype Studies.

Int J Mol Sci 2020 Apr 10;21(7). Epub 2020 Apr 10.

Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy.

Facioscapulohumeral muscular dystrophy (FSHD) is characterized by incomplete penetrance and intra-familial clinical variability. The disease has been associated with the genetic and epigenetic features of the D4Z4 repetitive elements at 4q35. Recently, D4Z4 hypomethylation has been proposed as a reliable marker in the FSHD diagnosis. We exploited the Italian Registry for FSHD, in which FSHD families are classified using the Clinical Comprehensive Evaluation Form (CCEF). A total of 122 index cases showing a classical FSHD phenotype (CCEF, category A) and 110 relatives were selected to test with the receiver operating characteristic (ROC) curve, the diagnostic and predictive value of D4Z4 methylation. Moreover, we performed DNA methylation analysis in selected large families with reduced penetrance characterized by the co-presence of subjects carriers of one D4Z4 reduced allele with no signs of disease or presenting the classic FSHD clinical phenotype. We observed a wide variability in the D4Z4 methylation levels among index cases revealing no association with clinical manifestation or disease severity. By extending the analysis to family members, we revealed the low predictive value of D4Z4 methylation in detecting the affected condition. In view of the variability in D4Z4 methylation profiles observed in our large cohort, we conclude that D4Z4 methylation does not mirror the clinical expression of FSHD. We recommend that measurement of this epigenetic mark must be interpreted with caution in clinical practice.
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http://dx.doi.org/10.3390/ijms21072635DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7178248PMC
April 2020

Does DNA Methylation Matter in FSHD?

Genes (Basel) 2020 02 28;11(3). Epub 2020 Feb 28.

Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, 4,41121 Modena, Italy.

Facioscapulohumeral muscular dystrophy (FSHD) has been associated with the genetic and epigenetic molecular features of the CpG-rich D4Z4 repeat tandem array at 4q35. Reduced DNA methylation of D4Z4 repeats is considered part of the FSHD mechanism and has been proposed as a reliable marker in the FSHD diagnostic procedure. We considered the assessment of D4Z4 DNA methylation status conducted on distinct cohorts using different methodologies. On the basis of the reported results we conclude that the percentage of DNA methylation detected at D4Z4 does not correlate with the disease status. Overall, data suggest that in the case of FSHD1, D4Z4 hypomethylation is a consequence of the chromatin structure present in the contracted allele, rather than a proxy of its function. Besides, CpG methylation at D4Z4 DNA is reduced in patients presenting diseases unrelated to muscle progressive wasting, like Bosma Arhinia and Microphthalmia syndrome, a developmental disorder, as well as ICF syndrome. Consistent with these observations, the analysis of epigenetic reprogramming at the D4Z4 locus in human embryonic and induced pluripotent stem cells indicate that other mechanisms, independent from the repeat number, are involved in the control of the epigenetic structure at D4Z4.
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http://dx.doi.org/10.3390/genes11030258DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7140823PMC
February 2020

Phenotype may predict the clinical course of facioscapolohumeral muscular dystrophy.

Muscle Nerve 2019 06 4;59(6):711-713. Epub 2019 Apr 4.

Department of Clinical and Experimental Medicine, University of Pisa, via Roma 67 56126, Pisa, Italy.

Introduction: The correct phenotypic classification of patients with facioscapulohumeral muscular dystrophy (FSHD) is crucial for directing genetic diagnosis and for the definition of outcome measures in clinical trials.

Methods: Our objective was to ascertain the utility of the Comprehensive Clinical Evaluation Form (CCEF), the clinical classification proposed by the Italian Clinical Network for FSHD, in an independent FSHD patient population from the UK FSHD Patient Registry. We subdivided the patients into group 1, classic FSHD phenotype/category A of CCEF, and group 2, facial sparing phenotypes/category B1 of CCEF.

Results: Among 642 patients with FSHD1, 68.1% reported facial and shoulder weakness, whereas 24.1% reported shoulder weakness without facial impairment. The phenotype in group 2 was milder, with a higher mean age at onset (P < 0.0001) and less severe motor disability.

Discussion: Patients with different FSHD phenotypes may have different disease courses. Muscle Nerve 59:711-713, 2019.
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http://dx.doi.org/10.1002/mus.26474DOI Listing
June 2019

Genotype-phenotype correlation: The ultimate challenge in facioscapolohumeral muscular dystrophy.

Authors:
Rossella Tupler

Eur J Paediatr Neurol 2018 09;22(5):737

Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy; Department of Molecular Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, USA. Electronic address:

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http://dx.doi.org/10.1016/j.ejpn.2018.07.010DOI Listing
September 2018

Early onset facioscapulohumeral dystrophy - a systematic review using individual patient data.

Neuromuscul Disord 2017 Dec 21;27(12):1077-1083. Epub 2017 Sep 21.

Department of Neurology, Donders Centre for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands.

Infantile or early onset is estimated to occur in around 10% of all facioscapulohumeral dystrophy (FSHD) patients. Although small series of early onset FSHD patients have been reported, comprehensive data on the clinical phenotype is missing. We performed a systematic literature search on the clinical features of early onset FSHD comprising a total of 43 articles with individual data on 227 patients. Additional data from four cohorts was provided by the authors. Mean age at reporting was 18.8 years, and 40% of patients were wheelchair-dependent at that age. Half of the patients had systemic features, including hearing loss (40%), retinal abnormalities (37%) and developmental delay (8%). We found an inverse correlation between repeat size and disease severity, similar to adult-onset FSHD. De novo FSHD1 mutations were more prevalent than in adult-onset FSHD. Compared to adult FSHD, our findings indicate that early onset FSHD is overall characterized by a more severe muscle phenotype and a higher prevalence of systemic features. However, similar as in adults, a significant clinical heterogeneity was observed. Based on this, we consider early onset FSHD to be on the severe end of the FSHD disease spectrum. We found natural history studies and treatment studies to be very scarce in early onset FSHD, therefore longitudinal studies are needed to improve prognostication, clinical management and trial-readiness.
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http://dx.doi.org/10.1016/j.nmd.2017.09.007DOI Listing
December 2017

Aberrant Compartment Formation by HSPB2 Mislocalizes Lamin A and Compromises Nuclear Integrity and Function.

Cell Rep 2017 Aug;20(9):2100-2115

Department of Biomedical, Metabolic and Neuronal Sciences, University of Modena and Reggio Emilia, and Center for Neuroscience and Neurotechnology, 41125 Modena, Italy. Electronic address:

Small heat shock proteins (HSPBs) contain intrinsically disordered regions (IDRs), but the functions of these IDRs are still unknown. Here, we report that, in mammalian cells, HSPB2 phase separates to form nuclear compartments with liquid-like properties. We show that phase separation requires the disordered C-terminal domain of HSPB2. We further demonstrate that, in differentiating myoblasts, nuclear HSPB2 compartments sequester lamin A. Increasing the nuclear concentration of HSPB2 causes the formation of aberrant nuclear compartments that mislocalize lamin A and chromatin, with detrimental consequences for nuclear function and integrity. Importantly, phase separation of HSPB2 is regulated by HSPB3, but this ability is lost in two identified HSPB3 mutants that are associated with myopathy. Our results suggest that HSPB2 phase separation is involved in reorganizing the nucleoplasm during myoblast differentiation. Furthermore, these findings support the idea that aberrant HSPB2 phase separation, due to HSPB3 loss-of-function mutations, contributes to myopathy.
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http://dx.doi.org/10.1016/j.celrep.2017.08.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5583511PMC
August 2017

225th ENMC international workshop:: A global FSHD registry framework, 18-20 November 2016, Heemskerk, The Netherlands.

Neuromuscul Disord 2017 08 12;27(8):782-790. Epub 2017 Apr 12.

Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy. Electronic address:

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http://dx.doi.org/10.1016/j.nmd.2017.04.004DOI Listing
August 2017

The genetic basis of undiagnosed muscular dystrophies and myopathies: Results from 504 patients.

Neurology 2016 07 8;87(1):71-6. Epub 2016 Jun 8.

From the Dipartimento di Biochimica Biofisica e Patologia Generale (M.S., G.D.F., A. Torella, A.G., T.G., F.D.V.B., G.E., G.P., V.N.), Seconda Università di Napoli; Telethon Institute of Genetics and Medicine (M.S., G.D.F., A. Torella, M. Mutarelli, V.S.M., A.G., T.G., G.E., V.N.), Pozzuoli; U.O.C. Neurologia Pediatrica e Malattie Muscolari (C.F., C.M., C.B.), IRCCS Istituto Giannina Gaslini, Genova; Centro Dino Ferrari, Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti (F.M., D.R., G.P.C.), and Neuromuscular and Rare Disease Unit, Dipartimento di Neuroscienze (M. Moggio), Università degli Studi di Milano, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan; Dipartimento di Neuroscienze (M. Fanin, E.P.), Università di Padova; Dipartimento di Neuroscienze e Scienze Riproduttive ed Odontostomatologiche (L.R., L.S.), Università degli Studi di Napoli "Federico II," Napoli; Dipartimento di Medicina Clinica e Sperimentale (G.R., G.S.), Università degli Studi di Pisa; Medicina Molecolare (G.A., F.M.S.), IRCCS Fondazione Stella Maris, Pisa; Dipartimento di Medicina Sperimentale (L. Passamano, P.D., R.P., L. Politano) and Dipartimento di Scienze Mediche, Chirurgiche, Neurologiche, Metaboliche, e dell'Invecchiamento (O.F., S.S., G.D.I.), Seconda Università di Napoli; Dipartimento di Neuroscienze (A.R., M. Mora, L.M.), Istituto Besta, Milano; Don Carlo Gnocchi ONLUS Foundation (G.T.), Milano; Dipartimento di Neuroscienze (A.D., E.B.), IRCCS Ospedale Pediatrico Bambino Gesù, Roma, Italy; Center for Medical Genetics (S.J., K.C.) and Department of Neurology (J.D.B.), Ghent University Hospital, Belgium; Dipartimento di Neuroscienze (O.M., C.R., S.M., A. Toscano), Università degli Studi di Messina, Italy; Folkhälsan Institute of Genetics (A.E., P.H., B.U.), University of Helsinki, Finland; Section for Neuromuscular Diseases and Neuropathies (M. Filosto), Unit of Clinical Neurology, University Hospital 'Spedali Civili,' Brescia, Italy; Neuromusc

Objective: To apply next-generation sequencing (NGS) for the investigation of the genetic basis of undiagnosed muscular dystrophies and myopathies in a very large cohort of patients.

Methods: We applied an NGS-based platform named MotorPlex to our diagnostic workflow to test muscle disease genes with a high sensitivity and specificity for small DNA variants. We analyzed 504 undiagnosed patients mostly referred as being affected by limb-girdle muscular dystrophy or congenital myopathy.

Results: MotorPlex provided a complete molecular diagnosis in 218 cases (43.3%). A further 160 patients (31.7%) showed as yet unproven candidate variants. Pathogenic variants were found in 47 of 93 genes, and in more than 30% of cases, the phenotype was nonconventional, broadening the spectrum of disease presentation in at least 10 genes.

Conclusions: Our large DNA study of patients with undiagnosed myopathy is an example of the ongoing revolution in molecular diagnostics, highlighting the advantages in using NGS as a first-tier approach for heterogeneous genetic conditions.
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http://dx.doi.org/10.1212/WNL.0000000000002800DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4932234PMC
July 2016

A novel clinical tool to classify facioscapulohumeral muscular dystrophy phenotypes.

J Neurol 2016 Jun 28;263(6):1204-14. Epub 2016 Apr 28.

Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.

Based on the 7-year experience of the Italian Clinical Network for FSHD, we revised the FSHD clinical form to describe, in a harmonized manner, the phenotypic spectrum observed in FSHD. The new Comprehensive Clinical Evaluation Form (CCEF) defines various clinical categories by the combination of different features. The inter-rater reproducibility of the CCEF was assessed between two examiners using kappa statistics by evaluating 56 subjects carrying the molecular marker used for FSHD diagnosis. The CCEF classifies: (1) subjects presenting facial and scapular girdle muscle weakness typical of FSHD (category A, subcategories A1-A3), (2) subjects with muscle weakness limited to scapular girdle or facial muscles (category B subcategories B1, B2), (3) asymptomatic/healthy subjects (category C, subcategories C1, C2), (4) subjects with myopathic phenotype presenting clinical features not consistent with FSHD canonical phenotype (D, subcategories D1, D2). The inter-rater reliability study showed an excellent concordance of the final four CCEF categories with a κ equal to 0.90; 95 % CI (0.71; 0.97). Absolute agreement was observed for categories C and D, an excellent agreement for categories A [κ = 0.88; 95 % CI (0.75; 1.00)], and a good agreement for categories B [κ = 0.79; 95 % CI (0.57; 1.00)]. The CCEF supports the harmonized phenotypic classification of patients and families. The categories outlined by the CCEF may assist diagnosis, genetic counseling and natural history studies. Furthermore, the CCEF categories could support selection of patients in randomized clinical trials. This precise categorization might also promote the search of genetic factor(s) contributing to the phenotypic spectrum of disease.
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http://dx.doi.org/10.1007/s00415-016-8123-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4893383PMC
June 2016

Clinical expression of facioscapulohumeral muscular dystrophy in carriers of 1-3 D4Z4 reduced alleles: experience of the FSHD Italian National Registry.

BMJ Open 2016 Jan 5;6(1):e007798. Epub 2016 Jan 5.

Department of Science of Life, Institute of Biology, University of Modena and Reggio Emilia, Modena, Italy Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.

Objectives: Facioscapulohumeral muscular dystrophy type 1 (FSHD1) has been genetically linked to reduced numbers (≤ 8) of D4Z4 repeats at 4q35. Particularly severe FSHD cases, characterised by an infantile onset and presence of additional extra-muscular features, have been associated with the shortest D4Z4 reduced alleles with 1-3 repeats (1-3 DRA). We searched for signs of perinatal onset and evaluated disease outcome through the systematic collection of clinical and anamnestic records of de novo and familial index cases and their relatives, carrying 1-3 DRA.

Setting: Italy.

Participants: 66 index cases and 33 relatives carrying 1-3 DRA.

Outcomes: The clinical examination was performed using the standardised FSHD evaluation form with validated inter-rater reliability. To investigate the earliest signs of disease, we designed the Infantile Anamnestic Questionnaire (IAQ). Comparison of age at onset was performed using the non-parametric Wilcoxon rank-sum or Kruskal-Wallis test. Comparison of the FSHD score was performed using a general linear model and Wald test. Kaplan-Meier survival analysis was used to estimate the age-specific cumulative motor impairment risk.

Results: No patients had perinatal onset. Among index cases, 36 (54.5%) showed the first signs by 10 years of age. The large majority of patients with early disease onset (26 out of 36, 72.2%) were de novo; whereas the majority of patients with disease onset after 10 years of age were familial (16, 53.3%). Comparison of the disease severity outcome between index cases with age at onset before and over 10 years of age, failed to detect statistical significance (Wald test p value=0.064). Of 61 index cases, only 17 (27.9%) presented extra-muscular conditions. Relatives carrying 1-3 DRA showed a large clinical variability ranging from healthy subjects, to patients with severe motor impairment.

Conclusions: The size of the D4Z4 allele is not always predictive of severe clinical outcome. The high degree of clinical variability suggests that additional factors contribute to the phenotype complexity.
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http://dx.doi.org/10.1136/bmjopen-2015-007798DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4716236PMC
January 2016

FHL1 reduces dystrophy in transgenic mice overexpressing FSHD muscular dystrophy region gene 1 (FRG1).

PLoS One 2015 19;10(2):e0117665. Epub 2015 Feb 19.

Department of Biochemistry & Molecular Biology, Monash University, Clayton, Victoria, 3800, Australia.

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal-dominant disease with no effective treatment. The genetic cause of FSHD is complex and the primary pathogenic insult underlying the muscle disease is unknown. Several disease candidate genes have been proposed including DUX4 and FRG1. Expression analysis studies of FSHD report the deregulation of genes which mediate myoblast differentiation and fusion. Transgenic mice overexpressing FRG1 recapitulate the FSHD muscular dystrophy phenotype. Our current study selectively examines how increased expression of FRG1 may contribute to myoblast differentiation defects. We generated stable C2C12 cell lines overexpressing FRG1, which exhibited a myoblast fusion defect upon differentiation. To determine if myoblast fusion defects contribute to the FRG1 mouse dystrophic phenotype, this strain was crossed with skeletal muscle specific FHL1-transgenic mice. We previously reported that FHL1 promotes myoblast fusion in vitro and FHL1-transgenic mice develop skeletal muscle hypertrophy. In the current study, FRG1 mice overexpressing FHL1 showed an improvement in the dystrophic phenotype, including a reduced spinal kyphosis, increased muscle mass and myofiber size, and decreased muscle fibrosis. FHL1 expression in FRG1 mice, did not alter satellite cell number or activation, but enhanced myoblast fusion. Primary myoblasts isolated from FRG1 mice showed a myoblast fusion defect that was rescued by FHL1 expression. Therefore, increased FRG1 expression may contribute to a muscular dystrophy phenotype resembling FSHD by impairing myoblast fusion, a defect that can be rescued by enhanced myoblast fusion via expression of FHL1.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0117665PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4335040PMC
November 2015

An integrated approach in a case of facioscapulohumeral dystrophy.

BMC Musculoskelet Disord 2014 May 15;15:155. Epub 2014 May 15.

LUSAMMR Laboratory for Motor Activities in Rare Diseases, Voghera, University of Pavia, Via Forlanini 6, Pavia 27100, Italy.

Background: Muscle fatigue, weakness and atrophy are basilar clinical features that accompany facioscapulohumeral dystrophy (FSHD) the third most common muscular dystrophy.No therapy is available for FSHD.

Case Presentation: We describe the effects of 6mo exercise therapy and nutritional supplementation in a 43-year-old woman severely affected by FSHD.

Conclusion: A mixed exercise program combined with nutritional supplementation can be safely used with beneficial effects in selected patients with FSHD.
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http://dx.doi.org/10.1186/1471-2474-15-155DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4032568PMC
May 2014

Altered Tnnt3 characterizes selective weakness of fast fibers in mice overexpressing FSHD region gene 1 (FRG1).

Am J Physiol Regul Integr Comp Physiol 2014 Jan 4;306(2):R124-37. Epub 2013 Dec 4.

Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy;

Facioscapulohumeral muscular dystrophy (FSHD), a common hereditary myopathy, is characterized by atrophy and weakness of selective muscle groups. FSHD is considered an autosomal dominant disease with incomplete penetrance and unpredictable variability of clinical expression within families. Mice overexpressing FRG1 (FSHD region gene 1), a candidate gene for this disease, develop a progressive myopathy with features of the human disorder. Here, we show that in FRG1-overexpressing mice, fast muscles, which are the most affected by the dystrophic process, display anomalous fast skeletal troponin T (fTnT) isoform, resulting from the aberrant splicing of the Tnnt3 mRNA that precedes the appearance of dystrophic signs. We determine that muscles of FRG1 mice develop less strength due to impaired contractile properties of fast-twitch fibers associated with an anomalous MyHC-actin ratio and a reduced sensitivity to Ca(2+). We demonstrate that the decrease of Ca(2+) sensitivity of fast-twitch fibers depends on the anomalous troponin complex and can be rescued by the substitution with the wild-type proteins. Finally, we find that the presence of aberrant splicing isoforms of TNNT3 characterizes dystrophic muscles in FSHD patients. Collectively, our results suggest that anomalous TNNT3 profile correlates with the muscle impairment in both humans and mice. On the basis of these results, we propose that aberrant fTnT represents a biological marker of muscle phenotype severity and disease progression.
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http://dx.doi.org/10.1152/ajpregu.00379.2013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3921317PMC
January 2014

Large scale genotype-phenotype analyses indicate that novel prognostic tools are required for families with facioscapulohumeral muscular dystrophy.

Brain 2013 Nov 11;136(Pt 11):3408-17. Epub 2013 Sep 11.

1 Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, via Roma 67, 56126 Pisa, Italy.

Facioscapulohumeral muscular dystrophy has been genetically linked to reduced numbers (≤ 8) of D4Z4 repeats at 4q35 combined with 4A(159/161/168) DUX4 polyadenylation signal haplotype. However, we have recently reported that 1.3% of healthy individuals carry this molecular signature and 19% of subjects affected by facioscapulohumeral muscular dystrophy do not carry alleles with eight or fewer D4Z4 repeats. Therefore, prognosis for subjects carrying or at risk of carrying D4Z4 reduced alleles has become more complicated. To test for additional prognostic factors, we measured the degree of motor impairment in a large group of patients affected by facioscapulohumeral muscular dystrophy and their relatives who are carrying D4Z4 reduced alleles. The clinical expression of motor impairment was assessed in 530 subjects, 163 probands and 367 relatives, from 176 unrelated families according to a standardized clinical score. The associations between clinical severity and size of D4Z4 allele, degree of kinship, gender, age and 4q haplotype were evaluated. Overall, 32.2% of relatives did not display any muscle functional impairment. This phenotype was influenced by the degree of relation with proband, because 47.1% of second- through fifth-degree relatives were unaffected, whereas only 27.5% of first-degree family members did not show motor impairment. The estimated risk of developing motor impairment by age 50 for relatives carrying a D4Z4 reduced allele with 1-3 repeats or 4-8 repeats was 88.7% and 55%, respectively. Male relatives had a mean score significantly higher than females (5.4 versus 4.0, P = 0.003). No 4q haplotype was exclusively associated with the presence of disease. In 13% of families in which D4Z4 alleles with 4-8 repeats segregate, the diagnosis of facioscapulohumeral muscular dystrophy was reported only in one generation. In conclusion, this large-scale analysis provides further information that should be taken into account when counselling families in which a reduced allele with 4-8 D4Z4 repeats segregates. In addition, the reduced expression of disease observed in distant relatives suggests that a family's genetic background plays a role in the occurrence of facioscapulohumeral muscular dystrophy. These results indicate that the identification of new susceptibility factors for this disease will require an accurate classification of families.
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http://dx.doi.org/10.1093/brain/awt226DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3808686PMC
November 2013

Large-scale population analysis challenges the current criteria for the molecular diagnosis of fascioscapulohumeral muscular dystrophy.

Am J Hum Genet 2012 Apr;90(4):628-35

Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Italy.

Facioscapulohumeral muscular dystrophy (FSHD) is a common hereditary myopathy causally linked to reduced numbers (≤8) of 3.3 kilobase D4Z4 tandem repeats at 4q35. However, because individuals carrying D4Z4-reduced alleles and no FSHD and patients with FSHD and no short allele have been observed, additional markers have been proposed to support an FSHD molecular diagnosis. In particular a reduction in the number of D4Z4 elements combined with the 4A(159/161/168)PAS haplotype (which provides the possibility of expressing DUX4) is currently used as the genetic signature uniquely associated with FSHD. Here, we analyzed these DNA elements in more than 800 Italian and Brazilian samples of normal individuals unrelated to any FSHD patients. We find that 3% of healthy subjects carry alleles with a reduced number (4-8) of D4Z4 repeats on chromosome 4q and that one-third of these alleles, 1.3%, occur in combination with the 4A161PAS haplotype. We also systematically characterized the 4q35 haplotype in 253 unrelated FSHD patients. We find that only 127 of them (50.1%) carry alleles with 1-8 D4Z4 repeats associated with 4A161PAS, whereas the remaining FSHD probands carry different haplotypes or alleles with a greater number of D4Z4 repeats. The present study shows that the current genetic signature of FSHD is a common polymorphism and that only half of FSHD probands carry this molecular signature. Our results suggest that the genetic basis of FSHD, which is remarkably heterogeneous, should be revisited, because this has important implications for genetic counseling and prenatal diagnosis of at-risk families.
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http://dx.doi.org/10.1016/j.ajhg.2012.02.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3322229PMC
April 2012

Effects of creatine and exercise on skeletal muscle of FRG1-transgenic mice.

Can J Neurol Sci 2012 Mar;39(2):225-31

Department of Medical Sciences, McMaster University, Hamilton, Ontario, Canada.

Background: The FRG1-transgenic mouse displays muscle dysfunction and atrophy reminiscent of fascioscapulohumeral muscular dystrophy (FSHD) and could provide a model to determine potential therapeutic interventions.

Methods: To determine if FRG1 mice benefit from treatments that improve muscle mass and function, mice were treated with creatine alone (Cr) or in combination with treadmill exercise (CrEX).

Results: The CrEx treatment increased quadriceps weight, mitochondrial content (cytochome c oxidase (COX) activity, COX subunit one and four protein), and induced greater improvements in grip strength and rotarod fall speed. While Cr increased COX subunits one and four protein, no effect on muscle mass or performance was found. Since Cr resulted in no functional improvements, the benefits of CrEx may be mediated by exercise; however, the potential synergistic action of the combined treatment cannot be excluded.

Conclusion: Treatment with CrEx attenuates atrophy and muscle dysfunction associated with FRG1 overexpression. These data suggest exercise and creatine supplementation may benefit individuals with FSHD.
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http://dx.doi.org/10.1017/s0317167100013275DOI Listing
March 2012

Rippling muscle disease and facioscapulohumeral dystrophy-like phenotype in a patient carrying a heterozygous CAV3 T78M mutation and a D4Z4 partial deletion: Further evidence for "double trouble" overlapping syndromes.

Neuromuscul Disord 2012 Jun 14;22(6):534-40. Epub 2012 Jan 14.

Department of Neuroscience, University of Pisa, Pisa, Italy.

We report the first case of a heterozygous T78M mutation in the caveolin-3 gene (CAV3) associated with rippling muscle disease and proximal myopathy. The patient displayed also bilateral winged scapula with limited abduction of upper arms and marked asymmetric atrophy of leg muscles shown by magnetic resonance imaging. Immunohistochemistry on the patient's muscle biopsy demonstrated a reduction of caveolin-3 staining, compatible with the diagnosis of caveolinopathy. Interestingly, consistent with the possible diagnosis of FSHD, the patient carried a 35 kb D4Z4 allele on chromosome 4q35. We discuss the hypothesis that the two genetic mutations may exert a synergistic effect in determining the phenotype observed in this patient.
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http://dx.doi.org/10.1016/j.nmd.2011.12.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3359497PMC
June 2012

Facioscapulohumeral muscular dystrophy: new insights from compound heterozygotes and implication for prenatal genetic counselling.

J Med Genet 2012 Mar 3;49(3):171-8. Epub 2012 Jan 3.

Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Italy.

Background Facioscapulohumeral muscular dystrophy (FSHD) is considered an autosomal dominant disease with a prevalence of 1 in 20 000. Almost all patients with FSHD carry deletions of integral copies of tandem 3.3 kb repeats (D4Z4) located on chromosome 4q35. However, FSHD families have been reported in which individuals carrying a D4Z4-reduced allele remain asymptomatic. Recently, it has been proposed that the D4Z4-reduced allele is pathogenic only in association with the permissive haplotype, 4APAS. Methods and results Through the Italian National Registry for FSHD (INRF), genotype-phenotype correlations were extensively studied in 11 non-consanguineous families in which two D4Z4-reduced alleles segregate. Overall, 68 subjects carrying D4Z4-reduced alleles were examined, including 15 compound heterozygotes. It was found that in four families the only FSHD-affected subject was the compound heterozygote for the D4Z4-reduced allele, and 52.6% of subjects carrying a single D4Z4-reduced 4A161PAS haplotype were non-penetrant carriers; moreover, the population frequency of the 4A161PAS haplotype associated with a D4Z4-reduced allele was found to be as high as 1.2%. Conclusions This study reveals a high frequency of compound heterozygotes in the Italian population and the presence of D4Z4-reduced alleles with the 4A161PAS pathogenic haplotype in the majority of non-penetrant subjects in FSHD families with compound heterozygosity. These data suggest that carriers of FSHD-sized alleles with 4A161PAS haplotype are more common in the general population than expected on the basis of FSHD prevalence. These findings challenge the notion that FSHD is a fully penetrant autosomal dominant disorder uniquely associated with the 4A161PAS haplotype, with relevant repercussions for genetic counselling and prenatal diagnosis.
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http://dx.doi.org/10.1136/jmedgenet-2011-100454DOI Listing
March 2012

RNA interference improves myopathic phenotypes in mice over-expressing FSHD region gene 1 (FRG1).

Mol Ther 2011 Nov 5;19(11):2048-54. Epub 2011 Jul 5.

Molecular, Cellular, and Developmental Biology Graduate Program, The Ohio State University, Columbus, Ohio, USA.

Muscular dystrophies, and other diseases of muscle, arise from recessive and dominant gene mutations. Gene replacement strategies may be beneficial for the former, while gene silencing approaches may provide treatment for the latter. In the last two decades, muscle-directed gene therapies were primarily focused on treating recessive disorders. This disparity at least partly arose because feasible mechanisms to silence dominant disease genes lagged behind gene replacement strategies. With the discovery of RNA interference (RNAi) and its subsequent development as a promising new gene silencing tool, the landscape has changed. In this study, our objective was to demonstrate proof-of-principle for RNAi therapy of a dominant myopathy in vivo. We tested the potential of adeno-associated viral (AAV)-delivered therapeutic microRNAs, targeting the human Facioscapulohumeral muscular dystrophy (FSHD) region gene 1 (FRG1), to correct myopathic features in mice expressing toxic levels of human FRG1 (FRG1(-high) mice). We found that FRG1 gene silencing improved muscle mass, strength, and histopathological abnormalities associated with muscular dystrophy in FRG1(-high) mice, thereby demonstrating therapeutic promise for treatment of dominantly inherited myopathies using RNAi. This approach potentially applies to as many as 29 different gene mutations responsible for myopathies inherited as dominant disorders.
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http://dx.doi.org/10.1038/mt.2011.118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3222519PMC
November 2011

A standardized clinical evaluation of patients affected by facioscapulohumeral muscular dystrophy: The FSHD clinical score.

Muscle Nerve 2010 Aug;42(2):213-7

Department of Neurology, IRCCS Fondazione Ospedale Maggiore Policlinico, University of Milan, Milan, Italy.

To define numerically the clinical severity of facioscapulohumeral muscular dystrophy (FSHD), we developed a protocol that quantifies muscle weakness by combining the functional evaluation of six muscle groups affected in this disease. To validate reproducibility of the protocol, 69 patients were recruited. Each patient was evaluated by at least five neurologists, and an FSHD severity score was given by each examiner. The degree of agreement among clinicians' evaluations was measured by kappa-statistics. Nineteen subjects received a score between 0 and 1, 9 had a score between 2 and 4, 20 received a score between 5 and 10, and 8 had a score between 11 and 15. Of the 13 subjects with D4Z4 alleles within the normal range (ranging from 10 to 150 repeats), 12 obtained a score of 0 and only 1 had a score of 1. Kappa-statistics showed a very high concordance for all muscle groups. We developed a simple, reliable, easily used tool to define the clinical expression of FSHD. Longitudinal studies will assess its sensitivity and utility in measuring changes for widespread use.
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http://dx.doi.org/10.1002/mus.21671DOI Listing
August 2010

The MeCP2/YY1 interaction regulates ANT1 expression at 4q35: novel hints for Rett syndrome pathogenesis.

Hum Mol Genet 2010 Aug 26;19(16):3114-23. Epub 2010 May 26.

Laboratory of Genetic and Epigenetic Control of Gene Expression, Department of Structural and Functional Biology, University of Insubria, 21052 Busto Arsizio, VA, Italy.

Rett syndrome is a severe neurodevelopmental disorder mainly caused by mutations in the transcriptional regulator MeCP2. Although there is no effective therapy for Rett syndrome, the recently discovered disease reversibility in mice suggests that there are therapeutic possibilities. Identification of MeCP2 targets or modifiers of the phenotype can facilitate the design of curative strategies. To identify possible novel MeCP2 interactors, we exploited a bioinformatic approach and selected Ying Yang 1 (YY1) as an interesting candidate. We demonstrate that MeCP2 interacts in vitro and in vivo with YY1, a ubiquitous zinc-finger epigenetic factor regulating the expression of several genes. We show that MeCP2 cooperates with YY1 in repressing the ANT1 gene encoding a mitochondrial adenine nucleotide translocase. Importantly, ANT1 mRNA levels are increased in human and mouse cell lines devoid of MeCP2, in Rett patient fibroblasts and in the brain of Mecp2-null mice. We further demonstrate that ANT1 protein levels are upregulated in Mecp2-null mice. Finally, the identified MeCP2-YY1 interaction, together with the well-known involvement of YY1 in the regulation of D4Z4-associated genes at 4q35, led us to discover the anomalous depression of FRG2, a subtelomeric gene of unknown function, in Rett fibroblasts. Collectively, our data indicate that mutations in MeCP2 might cause the aberrant overexpression of genes located at a specific locus, thus providing new candidates for the pathogenesis of Rett syndrome. As both ANT1 mutations and overexpression have been associated with human diseases, we consider it highly relevant to address the consequences of ANT1 deregulation in Rett syndrome.
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http://dx.doi.org/10.1093/hmg/ddq214DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908467PMC
August 2010