Predictors of mortality and cardiovascular outcomes in Emery-Dreifuss muscular dystrophy in a long-term follow-up.

BACKGROUND: Emery-Dreifuss muscular dystrophy (EDMD) is an extremely rare muscular dystrophy due to either emerinopathy (EMD) or laminopathy (LMNA). The main risk for patients is that of cardiovascular complications. AIMS: This study aimed to identify predictors of adverse clinical events in patients with EDMD in a long-term follow-up observation. METHODS: A total of 45 patients with confirmed EMD or LMNA mutation were included in the study. The relationships between clinical parameters, the overall survival rate, and risk factors for disease progression were assessed. The primary endpoint was defined as death, while the secondary endpoint comprised death, resuscitated cardiac arrest (RCA), heart transplant (HTX), stroke, end-stage heart failure (ESHF), and hospitalization due to heart failure (HF). RESULTS: During a median length of follow-up observation of ten years (interquartile range, 5-15), ten patients (22%) died, one suffered RCA, two had HTX, and six suffered ischemic strokes (13%). Seven patients developed ESHF, and eight were hospitalized due to HF. The secondary endpoint occurred in 16 patients (36%). LMNA mutation (hazard ratio [HR], 6.01; 95% confidence interval [CI], 1.61-22.4; P = 0.008) and higher serum N-terminal fragment of B-type natriuretic peptide (NT-proBNP) concentration (HR, 1.29; 95% CI, 1.06-1.56 per 100 pg/ml; P = 0.01) increased the risk of death. Higher tricuspid annular plane systolic excursion (TAPSE) decreased the risk for the secondary endpoint (HR, 0.78; 95% CI, 0.68-0.90 mm; P <0.001). NT-proBNP >257 pg/ml and TAPSE <21 mm may be assumed as the best cut-off values for the primary and secondary endpoints, respectively. CONCLUSIONS: LMNA mutation and higher NT-proBNP concentration were associated with increased mortality in EDMD. Lower TAPSE was a predictor of a composite secondary endpoint in EDMD.

Floppy infant syndrome as a first manifestation of LMNA-related congenital muscular dystrophy.

LMNA-related congenital muscular dystrophy (L-CMD) is the most severe phenotypic form of skeletal muscle laminopathies. This paper reports clinical presentation of the disease in 15 Polish patients from 13 families with genetically confirmed skeletal muscle laminopathy. In all these patients floppy infant syndrome was the first manifestation of the disease. The genetic diagnosis was established by next generation sequencing (targeted panel or exome; 11 patients) or classic Sanger sequencing (4 patients). In addition to known pathogenic LMNA variants: c.116A > G (p.Asn39Ser), c.745C > T (p.Arg249Trp), c.746G > A (p.Arg249Gln), c.1072G > A (p.Glu358Lys), c.1147G > A (p.Glu383Lys), c.1163G > C (p.Arg388Pro), c.1357C > T (p.Arg453Trp), c.1583C > G (p.Thr528Arg), we have identified three novel ones: c.121C > G (p.Arg41Gly), c.1127A > G (p.Tyr376Cys) and c.1160T > C (p.Leu387Pro). Eleven patients had de novo mutations, 4 - familial. In one family we observed intrafamilial variability of clinical course: severe L-CMD in the male proband, intermediate form in his sister and asymptomatic in their mother. One asymptomatic father had somatic mosaicism. L-CMD should be suspected in children with hypotonia in infancy and delayed motor development, who have poor head control, severe hyperlordosis and unstable and awkward gait. Serum creatine kinase may be high (~1000IU/l). Progression of muscle weakness is fast, leading to early immobilization. In some patients with L-CMD joint contractures can develop with time. MRI shows that the most frequently affected muscles are the serratus anterior, lumbar paraspinal, gluteus, vastus, adductor magnus, hamstrings, medial head of gastrocnemius and soleus. Ultra-rare laminopathies can be a relatively common cause of generalized hypotonia in children. Introduction of wide genome sequencing methods was a breakthrough in diagnostics of diseases with great clinical and genetic variability and allowed approach "from genotype do phenotype". However target sequencing of LMNA gene could be considered in selected patients with clinical picture suggestive for laminopathy.

Cardiac Arrhythmias in Muscular Dystrophies Associated with Emerinopathy and Laminopathy: A Cohort Study.

INTRODUCTION: Cardiac involvement in patients with muscular dystrophy associated with Lamin A/C mutations (LMNA) is characterized by atrioventricular conduction abnormalities and life-threatening cardiac arrhythmias. Little is known about cardiac involvement in patients with emerin mutation (EMD). The aim of our study was to describe and compare the prevalence and time distribution of cardiac arrhythmias at extended follow-up. PATIENTS AND METHODS: 45 consecutive patients affected by muscular dystrophy associated to laminopathy or emerinopathy were examined. All patients underwent clinical evaluation, 12-lead surface electrocardiogram (ECG), 24 h electrocardiographic monitoring, and cardiac implanted device interrogation. RESULTS: At the end of 11 (5.0-16.6) years of follow-up, 89% of the patients showed cardiac arrhythmias. The most prevalent was atrial standstill (AS) (31%), followed by atrial fibrillation/flutter (AF/Afl) (29%) and ventricular tachycardia (22%). EMD patients presented more frequently AF/AFl compared to LMNA (50% vs. 20%, p = 0.06). Half of the EMD patients presented with AS, whilst there was no occurrence of such in the LMNA (p = 0.001). Ventricular arrhythmias were found in 60% of patients with laminopathy compared to 3% in patients with emerinopathy (p < 0.001). The age of AVB occurrence was higher in the LMNA group (32.8 +/- 10.6 vs. 25.1 +/- 9.1, p = 0.03). CONCLUSIONS: Atrial arrhythmias are common findings in patients with muscular dystrophy associated with EMD/LMNA mutations; however, they occurred earlier in EMD patients. Ventricular arrhythmias were very common (60%) in LMNA and occurred definitely earlier compared to the EMD group.

Echocardiographic Features of Cardiomyopathy in Emery-Dreifuss Muscular Dystrophy.

BACKGROUND: Emery-Dreifuss muscular dystrophy (EDMD) is a very rare type of muscular dystrophy characterized by musculoskeletal abnormalities accompanied by cardiac defects. Two most common genetic subtypes are EDMD1 due to EMD and EDMD2 caused by LMNA gene mutations. The aim of the study was to characterize and compare the cardiac morphology and function in the two main genetic subgroups of EDMD with the use of echocardiography. METHODS: 41 patients with EDMD (29 EDMD1 and 12 EDMD2) as well as 25 healthy controls were enrolled in our study. Transthoracic echo with the use of a prescribed protocol was performed. RESULTS: Highly statistically significant differences with regard to left ventricle (LV) volumes between the EDMD and the control group were found. 51% of EDMD patients had an enlarged left atrium and as many as 71% had an enlarged right atrium. The LV ejection fraction (LVEF) was significantly lower in EDMD patients than in the control group which corresponded also with a lower systolic velocity of the mitral annulus. 43% of EDMD patients had LVEF below the normal limit. Diastolic dysfunction was detected in 17% of EDMD patients. There were no significant differences between the two types of EDMD in terms of diameters and volumes of any chamber, as well as the systolic function of both left and right ventricles. CONCLUSIONS: A significant number of EDMD patients present LV dilatation and different degrees of systolic dysfunction. Dilatation of the atria dominates over ventricle dilatation. We did not present any significant differences between EDMD1 and EDMD2 in terms of the morphology and the function of the heart.

X-Linked Emery-Dreifuss Muscular Dystrophy: Study Of X-Chromosome Inactivation and Its Relation with Clinical Phenotypes in Female Carriers.

X-linked Emery-Dreifuss muscular dystrophy (EDMD1) affects approximately 1:100,000 male births. Female carriers are usually asymptomatic but, in some cases, they may present clinical symptoms after age 50 at cardiac level, especially in the form of conduction tissue anomalies. The aim of this study was to evaluate the relation between heart involvement in symptomatic EDMD1 carriers and the X-chromosome inactivation (XCI) pattern. The XCI pattern was determined on the lymphocytes of 30 symptomatic and asymptomatic EDMD1 female carriers-25 familial and 5 sporadic cases-seeking genetic advice using the androgen receptor (AR) methylation-based assay. Carriers were subdivided according to whether they were above or below 50 years of age. A variance analysis was performed to compare the XCI pattern between symptomatic and asymptomatic carriers. The results show that 20% of EDMD1 carriers had cardiac symptoms, and that 50% of these were ≥50 years of age. The XCI pattern was similar in both symptomatic and asymptomatic carriers. Conclusions: Arrhythmias in EDMD1 carriers poorly correlate on lymphocytes to a skewed XCI, probably due to (a) the different embryological origin of cardiac conduction tissue compared to lymphocytes or (b) the preferential loss of atrial cells replaced by fibrous tissue.

Clinical aspects of Emery-Dreifuss muscular dystrophy.

Emery-Dreifuss muscular dystrophy (EDMD), clinically characterized by scapulo-humero-peroneal muscle atrophy and weakness, multi-joint contractures with spine rigidity and cardiomyopathy with conduction defects, is associated with structural/functional defect of genes that encode the proteins of nuclear envelope, including lamin A and several lamin-interacting proteins. This paper presents clinical aspects of EDMD in context to causative genes, genotype-phenotype correlation and its emplacement within phenotypic spectrum of skeletal muscle diseases associated with envelopathies.

Low-symptomatic skeletal muscle disease in patients with a cardiac disease - Diagnostic approach in skeletal muscle laminopathies.

Mild skeletal muscle symptoms might be accompanied with severe cardiac disease, sometimes indicating a serious inherited disorder. Very often it is a cardiologist who refers a patient with cardiomyopathy and/or cardiac arrhythmia and discrete muscle disease for neurological consultation, which helps to establish a proper diagnosis. Here we present three families in which a diagnosis of skeletal muscle laminopathy was made after careful examination of the members, who presented with cardiac arrhythmia and/or heart failure and a mild skeletal muscle disease, which together with positive family history allowed to direct the molecular diagnostics and then provide appropriate treatment and counseling.

Dysfunctional lamins as mediators of oxidative stress in Emery-Dreifuss muscular dystrophy.

Deficit of lamin A/C or emerin causes genetically transmitted Emery-Dreifuss muscular dystrophy (EDMD). As lamins are considered to be mediators of oxidative stress, the antioxidant/oxidant status was examined. The total oxidant/antioxidant status in serum was examined in 29 cases of Emery-Dreifuss muscular dystrophy. The study included 12 autosomal-dominant laminopathies (AD-EDMD), 17 X-linked emerinopathies (X-EDMD) and 20 age-matched normal subjects. Total oxidant status (TOS) was reduced in all cases, and the total antioxidant capacity (TAC) was found to be decreased in the majority of the patients (in 82.8%). A relationship between TOS level and disease progression was noted. No correlation between TOS/TAC level and cardiological or neurological parameters was detected. The results of the study indicate disturbances of redox balance in EDMD patients. Determination of TOS/TAC might help to assess the progress of the disease and the potential effectiveness of antioxidant therapy.

A novel de novo COL6A1 mutation emphasizes the role of intron 14 donor splice site defects as a cause of moderate-progressive form of ColVI myopathy - a case report and review of the genotype-phenotype correlation.

Collagen VI-related myopathy is a group of disorders affecting skeletal muscles and connective tissue. The most common symptoms are muscle weakness and joint deformities which limit the movement and progress over time. Several forms of collagen VI-related myopathies have been described: Bethlem myopathy, an intermediate form and Ullrich congenital muscular dystrophy, which is the most severe. Here we report a novel de novo c.1056+3A>C substitution in intron 14 of the COL6A1 gene encoding alpha-chains of collagen VI in a 13-year-old girl suffering from collagen VI (ColVI) myopathy. Analysis performed on cDNA generated from the RNA obtained from the patient's blood cells showed that the reported variant leads to the entire exon 14 skipping and probably results in an in-frame deletion of 18 amino acids of the COL6A1 protein. Clinical presentation, abnormal secretion of the collagen demonstrated in muscle biopsy and the COL6A1 c.1056+3A>C mutation justify classification of the presented case as ColVI myopathy with moderate-progressive course. Analysis of the literature indicates that the donor splice site of COL6A1 intron 14, associated with the phenotype of Bethlem myopathy or intermediate form, is a hot spot for ColVI myopathies.

The effect of the lamin A and its mutants on nuclear structure, cell proliferation, protein stability, and mobility in embryonic cells.

LMNA gene encodes for nuclear intermediate filament proteins lamin A/C. Mutations in this gene lead to a spectrum of genetic disorders, collectively referred to as laminopathies. Lamin A/C are widely expressed in most differentiated somatic cells but not in early embryos and some undifferentiated cells. To investigate the role of lamin A/C in cell phenotype maintenance and differentiation, which could be a determinant of the pathogenesis of laminopathies, we examined the role played by exogenous lamin A and its mutants in differentiated cell lines (HeLa, NHDF) and less-differentiated HEK 293 cells. We introduced exogenous wild-type and mutated (H222P, L263P, E358K D446V, and ∆50) lamin A into different cell types and analyzed proteins' impact on proliferation, protein mobility, and endogenous nuclear envelope protein distribution. The mutants give rise to a broad spectrum of nuclear phenotypes and relocate lamin C. The mutations ∆50 and D446V enhance proliferation in comparison to wild-type lamin A and control cells, but no changes in exogenous protein mobility measured by FRAP were observed. Interestingly, although transcripts for lamins A and C are at similar level in HEK 293 cells, only lamin C protein is detected in western blots. Also, exogenous lamin A and its mutants, when expressed in HEK 293 cells underwent posttranscriptional processing. Overall, our results provide new insight into the maintenance of lamin A in less-differentiated cells. Embryonic cells are very sensitive to lamin A imbalance, and its upregulation disturbs lamin C, which may influence gene expression and many regulatory pathways.

Limb-girdle muscular dystrophy with severe heart failure overlapping with lipodystrophy in a patient with LMNA mutation p.Ser334del.

Laminopathies, a group of heterogeneous disorders associated with lamin A/C gene (LMNA) mutations, encompass a wide spectrum of clinical phenotypes, which may present as separate disease or as overlapping syndromes. We describe a 35-year-old female in whom a novel sporadic heterozygous mutation c.1001_1003delGCC (p.Ser334del) of the LMNA gene was found. The patient presented with overlapping syndrome of heart failure secondary to dilated cardiomyopathy, limb-girdle dystrophy and partial lipodystrophy. Endomyocardial biopsy revealed strong up-regulation of HLA classes I and II antigens on microvessels and induction of the class I antigens on cardiomyocytes. On muscle biopsy, a wide range of fiber sizes and small clusters of inflammatory infiltrations were found. In the rapid progression of heart failure with arrhythmias or conduction defect, accompanied with muscle atrophy and lipodystrophy, the genetic disease should be taken into consideration. In addition, undefined inflammatory response and fibrosis in the heart or skeletal muscle might further justify screening of the lamin A/C gene.

Cardiac pacing in 21 patients with Emery-Dreifuss muscular dystrophy: a single-centre study with a 39-year follow-up.

BACKGROUND: Emery-Dreifuss muscular dystrophy (EDMD) is a genetic condition associated with cardiac arrhythmias. The patients typically develop early, asymptomatic bradyarrhythmia, which may lead to sudden death, preventable with a cardiac implantable electronic device (CIED). EDMD may be characterised by atrial electrical silence. Intra-operative electrophysiological evaluation of the myocardium helps ultimately determine the true nature of the disorder and select an appropriate CIED. AIM: To analyse permanent electrotherapy procedures in EDMD patients: atrial pacing limitations that stem from the electrophysiological properties of the myocardium and long-term follow-up of implanted devices. METHODS: A total of 21 EDMD patients (mean age 29 ± 9 years) with a CIED implanted (1976-2014) due to bradyarrhythmia were included in the study. The implantation procedures and factors determining the CIED type selection were analysed. RESULTS: CIEDs were implanted in five women and in 16 men with EDMD types 1 and 2 (mean follow-up: 11 ± 8 years). Intra-operatively assessed atrial electrophysiology resulted in changing the planned CIED type during the procedure in three men with EDMD type 1. Eventually, we implanted: eight DDD, one VDD, 11 VVI, and one CD-DR device, with four of the patients' devices switched later from DDD to VVI mode in response to electrophysiological changes in the atria. CONCLUSIONS: Intra-operative assessment of atrial electrophysiological properties resulted in changing the planned DDD mode for VVI in 19% of patients with EDMD type 1. Progression of the underlying disease over a 39-year follow-up resulted in a later change of the initially selected pacing mode from DDD to VVI in 40% of cases.

Emery-Dreifuss muscular dystrophy type 2 associated (?) with mild peripheral polyneuropathy.

In recent years numerous mutations in the LMNA gene encoding lamin A/C were shown to segregate with a wide spectrum of phenotypes. A recurrent p.R377H mutation in the LMNA gene was reported in patients with Emery-Dreifuss dystrophy (EDMD2) with various ethnic backgrounds. We present a patient with EDMD2 caused by a p.R377H mutation, associated with mild peripheral polyneuropathy. The analysis of peripheral myelin protein 22 (PMP22), ganglioside induced differentiation-associated protein 1 (GDAP1), gap junction ß-1 protein (GJB1), and myelin protein zero (MPZ) genes did not reveal mutations; however, we identified a new sequence intronic variant in the mitofusin 2 (MFN2) gene of unknown pathogenic significance. A complex phenotype in the presented patient might depend either on single mutation in the LMNA gene or on bigenic defect; therefore, a wide genetic investigation is needed to elucidate the molecular background of EDMD2/polyneuropathy in this case.

Tissue inhibitors of matrix metalloproteinases in serum are cardiac biomarkers in Emery-Dreifuss muscular dystrophy.

BACKGROUND: Tissue inhibitors of matrix metalloproteinases (TIMPs) are known to be involved in cardiovascular diseases. Hitherto, they have not been examined in dilated cardiomyopathy in the course of Emery-Dreifuss muscular dystrophy (EDMD). AIM: To define TIMPs in serum because they might help in defining cardiac dysfunction at the early cardiological stages of this disease and detect preclinical stages of cardiomyopathy. METHODS: Twenty-five EDMD patients connected with lamin A/C (AD-EDMD) or emerin (X-EDMD) deficiency and 20 healthy age-matched controls were examined. The serum levels of the tissue inhibitors TIMP-1, -2, -3 were quantified using the ELISA sandwich immunoassay procedure with appropriate antibodies. RESULTS: Serum levels of TIMP-1 were normal in autosomal AD-EDMD and increased in the majority of X-linked EDMD. The level of TIMP-2 was decreased in 25%/21% of AD-EDMD/X-EDMD cases. TIMP-3 serum level was significantly reduced in all the examined patients. Receiver operating curves indicated that in terms of sensitivity and specificity characteristics the performance of TIMP-3 (less that of TIMP-2) makes them the best markers of cardiac involvement among the examined TIMPs. CONCLUSIONS: Evidence shows that the levels of TIMP-3, and in some cases also TIMP-2, are decreased in EDMD. The decrease might be associated with an adverse effect on matrix metalloproteinases and remodelling of the myocardial matrix. The specific decrease of TIMP-3 indicates that this biomarker might help in early detection of cardiac involvement in EDMD. Up-regulation of TIMP-1 in the majority of patients with X-EDMD indicates increased myocardial extracellular matrix turnover, early onset of tissue remodelling, and may contribute to arrhythmia, frequently occurring in this form of the disease.

Professional activity of Emery-Dreifuss muscular dystrophy patients in Poland.

OBJECTIVES: Emery-Dreifuss muscular dystrophy (EDMD) is a very rare genetic disorder affecting skeletal and heart muscles. The aim of this study was to identify factors which might influence the ability to work in EDMD patients in Poland. MATERIAL AND METHODS: The study included 24 patients suffering from either of the two EDMD forms: 17 with emerinopathy (EDMD1; EDMD caused by mutations in the emerin gene) and 7 with laminopathy (EDMD2; EDMD caused by the lamin A/C gene mutations). After clinical evaluation of EDMD course, study participants were questioned about their education, current and former employment, and disability certificates and pensions. RESULTS: 54% of the study participants were employed, and 90% of them had job position corresponding to their education. Undertaking work did not correlate with the level of physical performance or disease complication, but it revealed statistically significant correlation with a higher level of education (p = 0.015). Only 23% of professionally active patients were employed in a sheltered workplace. Disability certificate was granted to all EDMD2 and to 90% of EDMD1 patients. All EDMD2 and 50% of EDMD1 patients received a disability pension, which reflects more severe course of EDMD2. CONCLUSIONS: Higher level of education increased the chance of employment, even if significant disability was present. Therefore, I hypothesize that advice on education and job counseling should be applied as early as possible after the diagnosis of EDMD.

Severe phenotypes of SMARD1 associated with novel mutations of the IGHMBP2 gene and nuclear degeneration of muscle and Schwann cells.

Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is a very rare autosomal recessive form of spinal muscular atrophy manifested in low birth weight, diaphragmatic palsy and distal muscular atrophy. Caused by a mutation in the IGHMBP2 gene, the disease is addressed here by reference to five Polish patients in which SMARD1 has been confirmed genetically. All presented a severe form of the disease and had evident symptoms during the second month of life; with four displaying weak cries, feeding difficulties and hypotonia from birth. Two were afflicted by severe dysfunction of the autonomic nervous system. Ultrastructural analysis of a muscle biopsy revealed progressive degeneration within the nuclei of the muscle cells and Schwann cells. Neuromuscular junctions were also defective. It proved possible to identify in our patients 6 novel IGHMBP2 mutations: three missense (c.595G>C, c.1682T>C and c.1794C>A), two nonsense (c.94C>T and c.1336C>T) and one in-frame deletion (c.1615_1623del). One nonsense mutation (c.429C>T) that had been described previously was also identified. Observation of our patients makes it clear that clinical picture is still the most important factor suggesting diagnosis of SMARD1, though further investigations concerning some of the symptoms are required. As the IGHMBP2 gene is characterized by significant heterogeneity, genetic counseling of affected families is rendered more complex. IGHMBP2 protein deficiency can lead to the degeneration of nuclei, in both muscle and Schwann cells.

Is mutation p.Arg168Gly in TPM3 gene responsible for Type 1 fiber hypoplasia and cap structure formation?

Congenital fiber type disproportion with delayed fiber type maturation and the appearance of cap structures were analyzed in a child with p.Arg168Gly mutation in TPM3 gene. Very narrow myotube-like Type 1 fibers with single nuclei decorated by cap structures seem to be a result of a failure in fusion process and mature fiber formation. Repeated mutations in exon 5 of TPM3 gene giving cap structures may be a different consequence of the loss of specific isoform normally operating in the fusion process and sarcomer formation.