Abstract Background Homozygous mutations in ANO5 , a gene encoding anoctamin 5, a putative calcium-activated chloride channel, have recently been reported in patients with adult-onset myopathies or ...isolated high-CK levels. Cardiomyopathy has not previously been reported in these populations despite a proven expression of anoctamin 5 in the cardiac muscle. Methods Patients presenting for the management of high-CK levels or overt myopathy with proven ANO5 mutations were prospectively investigated between June 2010 and March 2012 in Pitié Salpêtrière Hospital, according to a standardised protocol. Neurological and cardiological clinical examinations, CK assessment, electrocardiogram (ECG), and echocardiography were performed, as well as cardiac MRI and coronary CT angiography in patients with left ventricular (LV) dysfunction. Results Our study included 19 consecutive patients (male = 15, age = 46.2 ± 12.7 years) from 16 families. Five had asymptomatic high-CK levels and 14 had overt myopathy. One patient had a personal history of stable coronary artery disease with normal ventricular function. ECG showed ventricular premature beats in one patient. Echocardiography displayed LV dilatation in two patients, LV dysfunction in one, and both abnormalities in two who fulfilled criteria for dilated cardiomyopathy which was confirmed by cardiac MRI and normal CT angiography. Conclusions Dilated cardiomyopathy is a potential complication in patients with myopathies due to mutations in the ANO5 gene whose screening requires specific procedures.
Emery-Dreifuss muscular dystrophy (EDMD) is characterized by early contractures of elbows and Achilles tendons, slowly progressive muscle wasting and weakness, and a cardiomyopathy with conduction ...blocks which is life-threatening. Two modes of inheritance exist, X-linked (OMIM 310300) and autosomal dominant (EDMD-AD; OMIM 181350). EDMD-AD is clinically identical to the X-linked forms of the disease. Mutations in EMD, the gene encoding emerin, are responsible for the X-linked form. We have mapped the locus for EDMD-AD to an 8-cM interval on chromosome 1q11-q23 in a large French pedigree, and found that the EMD phenotype in four other small families was potentially linked to this locus. This region contains the lamin A/C gene (LMNA), a candidate gene encoding two proteins of the nuclear lamina, lamins A and C, produced by alternative splicing. We identified four mutations in LMNA that co-segregate with the disease phenotype in the five families: one nonsense mutation and three missense mutations. These results are the first identification of mutations in a component of the nuclear lamina as a cause of inherited muscle disorder. Together with mutations in EMD (refs 5,6), they underscore the potential importance of the nuclear envelope components in the pathogenesis of neuromuscular disorders.
Background and purpose
Our aim was to determine the prognostic value of urine and blood heteroplasmy in patients with the m.3243A>G mutation.
Methods
Adults with the m.3243A>G mutation referred to ...our institution between January 2000 and May 2014 were retrospectively included. The relationship between their baseline clinical characteristics, their mutation load in urine and blood, and major adverse events (MAEs) during follow‐up, defined as medical complications requiring a hospitalization or complicated by death, was studied.
Results
Of the 43 patients (age 45.6 ± 13.3 years) included in the study, 36 patients were symptomatic, including nine with evidence of focal brain involvement, and seven were asymptomatic. Over a 5.5 ± 4.0 year mean follow‐up duration, 14 patients (33%) developed MAEs. Patients with MAEs had a higher mutation load than others in urine (60.1% ± 13.8% vs. 40.6% ± 26.2%, P = 0.01) and in blood (26.9% ± 18.4% vs. 16.0% ± 12.1%, P = 0.03). Optimal cutoff values for the prediction of MAEs were 45% for urine and 35% for blood. In multivariate analysis, mutation load in urine ≥45% odds ratio 25.3; 95% confidence interval (CI) 1.1–567.8; P = 0.04, left ventricular hypertrophy (odds ratio 16.7; 95% CI 1.3– 222.5; P = 0.03) and seizures (odds ratio 48.3; 95% CI 2.5–933; P = 0.01) were associated with MAEs.
Conclusions
Patients with the m.3243A>G mutation are at high risk of MAEs, which can be independently predicted by mutation load in urine ≥45%, a personal history of seizures, and left ventricular hypertrophy.
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Cardiac tachyarrhythmias have rarely been studied in young patients with myotonic dystrophy type 1 (DM1). The authors observed major cardiac rhythm disturbances in 11 patients aged 10 to 18 years. ...Tachyarrhythmic events were more frequent than impulse conduction disorders. Wide variations in CTG expansion were observed among the population. Since physical exercise was a prominent arrhythmogenic factor, systematic exercise tests with EKG monitoring may be indicated in young patients with DM1.
Myofibrillar myopathies (MFM) have been described in the mid-1990s as a group of diseases sharing common histological features, including an abnormal accumulation of intrasarcoplasmic proteins, the ...presence of vacuoles and a disorganization of the intermyofibrillar network beginning at the Z-disk. The boundaries of this concept are still uncertain, and whereas six genes (DES, CRYAB, LDB3/ZASP, MYOT, FLNC and BAG3) are now classically considered as responsible for MFM, other entities such as FHL1 myopathy or Hereditary Myopathy with Early Respiratory Failure linked to mutations of titin can now as well be included in this group. The diagnosis of MFM is not always easy; as histological lesions can be focal, and muscle biopsy may be disappointing; this has led to a growing importance of muscle imaging, and the selectivity of muscle involvement has now been described in several disorders. Due to the rarity of these myopathies, if some clinical patterns (such as distal myopathy associated with cardiomyopathy due to desmin mutations) are now well known, surprises remain possible and should lead to systematic testing of the known genes in case of a typical histological presentation. In this paper, we aim at reviewing the data acquired on the six main genes listed above as well as presenting the experience from two French reference centres, Paris and Marseilles.
Les myopathies myofibrillaires (MMF) constituent un champ relativement neuf en myologie, dont les frontières restent incertaines. Il s’agit d’un groupe d’affection dont la définition est histologique, marquée par l’accumulation intracellulaire de protéines issues pour l’essentiel de la strie Z, dont la désorganisation précoce est patente en microscopie électronique. En un peu plus de 15 ans, six gènes principaux (DES, CRYAB, LDB3/ZASP, MYOT, FLNC et BAG3) sont venus rendre compte de cas caractérisés sur le plan histologique mais jusque-là inexpliqués sur le plan moléculaire. D’autres affections, comme les myopathies liées à FHL1 et les myopathies avec atteinte respiratoire précoce liées à la titine, sont certainement à rattacher à ce groupe. D’autres cas restent inexpliqués, laissant supposer l’existence de gènes encore inconnus, que les techniques de séquençage de nouvelle génération aideront sans doute à identifier. Le présent travail se propose de présenter une revue des données acquises sur les MMF dues aux six gènes principaux énoncés plus haut, ainsi que les connaissances en ce domaine issues de l’expérience des deux centres de référence français de Paris et Marseille.
Myofibrillar myopathies (MFM) are mostly adult-onset diseases characterized by progressive morphological alterations of the muscle fibers beginning in the Z-disk and the presence of protein ...aggregates in the sarcoplasm. They are mostly caused by mutations in different genes that encode Z-disk proteins, including DES, CRYAB, LDB3, MYOT, FLNC and BAG3. A large family of French origin, presenting an autosomal dominant pattern, characterized by cardiac arrhythmia associated to late-onset muscle weakness, was evaluated to clarify clinical, morphological and genetic diagnosis. Muscle weakness began during adult life (over 30 years of age), and had a proximal distribution. Histology showed clear signs of a myofibrillar myopathy, but with unusual, large inclusions. Subsequently, genetic testing was performed in MFM genes available for screening at the time of clinical/histological diagnosis, and desmin (DES), αB-crystallin (CRYAB), myotilin (MYOT) and ZASP (LDB3), were excluded. LMNA gene screening found the p.R296C variant which did not co-segregate with the disease. Genome wide scan revealed linkage to 7q.32, containing the FLNC gene. FLNC direct sequencing revealed a heterozygous c.3646T>A p.Tyr1216Asn change, co-segregating with the disease, in a highly conserved amino acid of the protein. Normal filamin C levels were detected by Western-blot analysis in patient muscle biopsies and expression of the mutant protein in NIH3T3 showed filamin C aggregates. This is an original FLNC mutation in a MFM family with an atypical clinical and histopathological presentation, given the presence of significantly focal lesions and prominent sarcoplasmic masses in muscle biopsies and the constant heart involvement preceding significantly the onset of the myopathy. Though a rare etiology, FLNC gene should not be excluded in early-onset arrhythmia, even in the absence of myopathy, which occurs later in the disease course.
Emery‐Dreifuss muscular dystrophy (EDMD) is characterized by early contractures of the elbows and Achilles tendons, slowly progressive muscle wasting and weakness, and life‐threatening cardiomyopathy ...with conduction blocks. We recently identified LMNA encoding two nuclear envelope proteins, lamins A and C, to be implicated in the autosomal dominant form of EDMD. Here, we report on the variability of the phenotype and spectrum of LMNA mutations in 53 autosomal dominant EDMD patients (36 members of 6 families and 17 sporadic cases). Twelve of the 53 patients showed cardiac involvement exclusively, although the remaining 41 all showed muscle weakness and contractures. We were able to identify a common phenotype among the patients with skeletal muscle involvement, consisting of humeroperoneal wasting and weakness, scapular winging, rigidity of the spine, and elbow and Achilles tendon contractures. The disease course was generally slow, but we observed either a milder phenotype characterized by late onset and a mild degree of weakness and contractures or a more severe phenotype with early presentation and a rapidly progressive course in a few cases. Mutation analysis identified 18 mutations in LMNA (ie, 1 nonsense mutation, 2 deletions of a codon, and 15 missense mutations). All the mutations were distributed between exons 1 and 9 in the region of LMNA that is common to lamins A and C. LMNA mutations arose de novo in 76% of the cases; 2 of these de novo mutations were typical hot spots, and 2 others were identified in 2 unrelated cases. There was no clear correlation between the phenotype and type or localization of the mutations within the gene. Moreover, a marked inter‐ and intra‐familial variability in the clinical expression of LMNA mutations exists, ranging from patients expressing the full clinical picture of EDMD to those characterized only by cardiac involvement, which points toward a significant role of possible modifier genes in the course of this disease. In conclusion, the high proportion of de novo mutations together with the large spectrum of both LMNA mutations and the expression of the disease should now prompt screening for LMNA in familial and sporadic cases of both EDMD and dilated cardiomyopathy associated with conduction system disease. Ann Neurol 2000;48:170–180
BÉCANE, H.–M., et al.: High Incidence of Sudden Death with Conduction System and Myocardial Disease Due to Lamins A and C Gene Mutation. We studied 54 living relatives from a large French kindred, ...among which 17 members presented with a cardiomyopathy transmitted on an autosomal dominant mode. Five of these individuals had clinical manifestations of muscle disease phenotypically consistent with Emery‐Dreifuss muscular dystrophy. Genetic analysis of this kindred had demonstrated a nonsense mutation in the LMNA gene located on chromosome 1q11–q23. This gene encodes lamins A and C, proteins of the nuclear lamina located on the inner face of the nuclear envelope. We retrospectively determined the cause of death of 15 deceased family members, 8 of whom had died suddenly, 2 as a first and single manifestation of the disease. The six other cases had histories of arrhythmias and left ventricular dysfunction before dying suddenly, and three of them died despite the prior implantation of a permanent pacemaker. The mean age of onset of cardiac symptoms among affected living family members was 33 years (range 15–47 years), and the first symptoms were due to marked atrioventricular conduction defects or sinus dysfunction, requiring the implantation of permanent pacemakers in seven cases. Myocardial dysfunction accompanied by ventricular arrhythmias developed rapidly in the course of the disease and resulted in severe dilated cardiomyopathy requiring cardiac transplantation in three cases. In conclusion, in patients presenting a life‐threatening familial or sporadic cardiac restricted phenotype similar to that described here, mutations in the lamins A and C gene should be looked for. In the genotypically affected individuals, cardiological and electrophysiological follow‐up should be performed to prevent sudden death that could occur rapidly in the evolution of such disease.
To determine the long-term incidence of cardiac life-threatening complications and death in patients with the m.3243A>G mutation, and to identify cardiac prognostic factors.
We retrospectively ...included patients carrying the m.3243A>G mutation who were admitted to the Neuromuscular Disease Clinic of Pitié Salpêtrière Hospital between January 1992 and December 2010. We collected information relative to their yearly neurologic and cardiac investigations, their mutation load in blood, urine, and muscle at initial admission, and the occurrence of cardiac life-threatening adverse events and death during follow-up.
Forty-one patients (median age = 47 years 36-55 years, men = 13) were included, of whom 38 had clinical manifestations of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) and 3 were asymptomatic. One patient had a personal history of cardiac transplantation. Cardiac investigations displayed left ventricular hypertrophy, left ventricular dysfunction, or both abnormalities in 18 patients, along with Wolff-Parkinson-White syndrome in 7, conduction system disease in 4, and atrial fibrillation in 1. Over a median 5-year (3-9 years) follow-up period, 11 patients died, including 3 due to heart failure; 7 had life-threatening adverse events, including 6 hospitalizations for severe heart failure and 1 resuscitated cardiac arrest. By multivariate analysis, left ventricular hypertrophy was the only parameter independently associated with occurrence of cardiac adverse events.
Patients with the m.3243A>G mutation have a high incidence of cardiac death and life-threatening adverse events. Left ventricular hypertrophy was the only parameter independently associated with occurrence of these events.
