Cardiac and muscle imaging findings in a family with X-linked Emery-Dreifuss muscular dystrophy

Signs and symptoms of carriers of non-DMD X-linked neuromuscular diseases: A scoping review

BACKGROUND

It has been known for long that females carrying pathogenic variants in the DMD gene often report symptoms and/or exhibit signs of the disease. However, a notable knowledge gap exists concerning the signs and symptoms of female carriers of other X-linked neuromuscular diseases (XLNMDs).

OBJECTIVE

This scoping review aims to provide a comprehensive outline of existing literature regarding the signs and symptoms of carriers of non-DMD XLNMDs to raise awareness among both researchers and clinicians.

METHODS

Three electronic databases were used for the literature search (PubMed, Embase, Web of Science). Studies on the signs and symptoms of carriers of non-DMD XLNMDs were included.

RESULTS

We included 44 articles for this review with a total of 354 carriers of non-DMD XLNMDs (mean age 43.9 years, std. deviation 17.4). Muscular signs and symptoms were reported for 125 carriers (X-linked myotubular myopathy (XLMTM): n = 96 (65%); Kennedy's disease (KD): n = 25 (32%); X-linked recessive Charcot-Marie-Tooth disease (CMTXR): n = 2 (15%); Uruguay faciocardiomusculoskeletal syndrome (FCMSU): n = 1 (33%); Barth syndrome (BS): n = 1 (100%)). In terms of ancillary investigations, abnormalities in histopathology and imaging were the most frequent with 44 carriers having abnormalities found by these testing (XLMTM: n = 36 (24%); Emery-Dreifuss muscular dystrophy 1 (EDMD1): n = 4 (5%); KD: n = 4 (5%) / XLMTM: n = 18 (12%); EDMD1: n = 1 (1%); KD: n = 5 (6%); X-linked myopathy with postural muscle atrophy (XMPMA): n = 19 (83%); BS: n = 1 (100%)). A difference between the number of EDMD1 carriers with cardiovascular signs and symptoms (n = 2 (1%)) and the number of carriers with abnormal electrocardiography tests (n = 20 (23%)) was also noted.

CONCLUSION

Carriers of non-DMD XLNMDs exhibit a variety of signs and symptoms that could impact quality of life, making it vital for clinicians to be aware of these patients.

Role of Cdkn2a in the Emery-Dreifuss Muscular Dystrophy Cardiac Phenotype

The Cdkn2a locus is one of the most studied tumor suppressor loci in the context of several cancer types. However, in the last years, its expression has also been linked to terminal differentiation and the activation of the senescence program in different cellular subtypes. Knock-out (KO) of the entire locus enhances the capability of stem cells to proliferate in some tissues and respond to severe physiological and non-physiological damages in different organs, including the heart. Emery-Dreifuss muscular dystrophy (EDMD) is characterized by severe contractures and muscle loss at the level of skeletal muscles of the elbows, ankles and neck, and by dilated cardiomyopathy. We have recently demonstrated, using the LMNA Δ8-11 murine model of Emery-Dreifuss muscular dystrophy (EDMD), that dystrophic muscle stem cells prematurely express non-lineage-specific genes early on during postnatal growth, leading to rapid exhaustion of the muscle stem cell pool. Knock-out of the Cdkn2a locus in EDMD dystrophic mice partially restores muscle stem cell properties. In the present study, we describe the cardiac phenotype of the LMNA Δ8-11 mouse model and functionally characterize the effects of KO of the Cdkn2a locus on heart functions and life expectancy.

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.

Is infrared thermography (IRT) a possible tool for the evaluation and follow up of Emery-Dreifuss muscular dystrophy? A preliminary study

HYPOTHESIS

The hypothesis of this work is that infrared thermography could become a valid tool for the diagnosis and follow-up of the Emery-Dreifuss disease due to putative temperature changes produced by a constant degenerative evolution of this muscular dystrophy.

TESTING THE HYPOTHESIS

To justify this hypothesis we proposed a pilot study with 2 brothers affected of Emery-Dreifuss who present a very different age, with the principal objective to evidence a possible evolution of this pathology. Acquisition and comparison of images of computerized axial tomography (CT) and thermography (IRT) of the distal limbs in 2 affected brothers.

DATA AND DISCUSSION

Important image correlations in the region of the thighs and the posterior region of the legs have been highlighted. The comparison between the CT and the thermography showed how the first results are encouraged and promising and open a possible new line of research on the evaluation and follow-up of this disease. Despite this, a larger number of studies are needed to validate the thermography as a diagnostic technique and follow-up of this pathology.

Muscle imaging in inherited and acquired muscle diseases

In this review we discuss the use of conventional (computed tomography, magnetic resonance imaging, ultrasound) and advanced muscle imaging modalities (diffusion tensor imaging, magnetic resonance spectroscopy) in hereditary and acquired myopathies. We summarize the data on specific patterns of muscle involvement in the major categories of muscle disease and provide recommendations on how to use muscle imaging in this field of neuromuscular disorders.

Muscle imaging in muscle dystrophies produced by mutations in the EMD and LMNA genes

Identifying the mutated gene that produces a particular muscle dystrophy is difficult because different genotypes may share a phenotype and vice versa. Muscle MRI is a useful tool to recognize patterns of muscle involvement in patients with muscle dystrophies and to guide the diagnosis process. The radiologic pattern of muscle involvement in patients with mutations in the EMD and LMNA genes has not been completely established. Our objective is to describe the pattern of muscle fatty infiltration in patients with mutations in the EMD and in the LMNA genes and to search for differences between the two genotypes that could be helpful to guide the genetic tests. We conducted a national multicenter study in 42 patients, 10 with mutations in the EMD gene and 32 with mutations in the LMNA gene. MRI or CT was used to study the muscles from trunk to legs. Patients had a similar pattern of fatty infiltration regardless of whether they had the mutation in the EMD or LMNA gene. The main muscles involved were the paravertebral, glutei, quadriceps, biceps, semitendinosus, semimembranosus, adductor major, soleus, and gastrocnemius. Involvement of peroneus muscle, which was more frequently affected in patients with mutations in the EMD gene, was useful to differentiate between the two genotypes. Muscle MRI/CT identifies a similar pattern of muscle fatty infiltration in patients with mutations in the EMD or the LMNA genes. The involvement of peroneus muscles could be useful to conduct genetic analysis in patients with an EDMD phenotype.

Genetic and clinical characteristics of skeletal and cardiac muscle in patients with lamin A/C gene mutations

Alterations of the lamin A/C (LMNA) gene are associated with different clinical entities, including disorders that affect skeletal and cardiac muscle, peripheral nerves, metabolism, bones, and disorders that cause premature aging. In this article we review the clinical and genetic characteristics of cardiac and skeletal muscle diseases related to alterations in the LMNA gene. There is no single explanation of how LMNA gene alterations may cause these disorders; however, important goals have been achieved in understanding the pathogenic effects of LMNA gene mutations on cardiac and skeletal muscle.