Mutations In Sarcoglycan Genes Research Articles

Bilateral Pallidal Stimulation in a Family With Myoclonus Dystonia Syndrome Due to a Mutation in the Sarcoglycan Gene

ObjectivesThe study aimed to present a family with myoclonus dystonia (M-D) syndrome due to a mutation in the epsilon sarcoglycan gene (SGCE). Three members of the family suffered from treatment-refractory severe myoclonic jerks of the neck, trunk, and upper extremities. The mild dystonic symptoms recognized as cervical dystonia or truncal dystonia affected all individuals. The efficacy of pharmacotherapy, including anticholinergic, dopaminergic, and serotoninergic drugs, has failed. One individual developed an alcohol dependency and suffered from alcoholic epilepsy. Materials and MethodsThe patients were referred for stereotactic surgery. All individuals underwent bilateral implantation of deep brain stimulation (DBS) leads into the posteroventrolateral segment of the globus pallidus internus (GPi). Surgeries were uneventful. The formal preoperative objective assessment included the Unified Myoclonus Rating Scale (UMRS) and the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). The postoperative UMRS and BFMDRS assessments were done only under continuous stimulation at 3, 6, and 12 months after the surgery and at the last available follow-up ranging from 6 to 15 months (mean, 10 months follow-up). ResultsAt the last follow-up visit, the rest and action parts of UMRS were improved by 93.3% and 88.2%, respectively, when compared to the baseline scores. The motor and disability scales of BFMDRS were improved by 77% and 43% at the last follow-up visit compared to the baseline BFMDRS scores. There were no hardware or stimulation-induced complications over the follow-up period. Positive social adjustment allowed two patients to regain jobs and one patient continued his education and hobbies. ConclusionOur experience gathered in three individuals in the family with a mutation in SGCE indicates that bilateral GPi DBS can be an effective and safe treatment for disabling pharmacological resistant, intractable M-D syndrome.

Favorable response to carbamazepine therapy in genetically proven myoclonus-dystonia child

BackgroundMyoclonus dystonia (MDS) is a dominantly inherited genetic disorder caused by loss-of-function mutations in the epsilon sarcoglycan gene (SGCE).Case presentationWe here in report a twenty months old Saudi boy who presented to us with a concern that the child is unable to walk properly. On assessment, he was flexing his left arm and left leg that usually followed by a back-ward fall. Diagnosis of dystonia induced with initiation of movement was suggested that later on proven genetically to be pathogenic mutation of sarcoglycan gene. Carbamazepine therapy was initiated with dramatic response. Response was maintained at 4 years follow up.ConclusionsOur patient and the other previously reported cases might highlight the response of SGCE mutations to carbamazepine therapy.

Milder forms of α-sarcoglicanopathies diagnosed in adulthood by NGS analysis

Introduction: Sarcoglycanopathies (LGMD 2C2F) are a subgroup of limb-girdle muscular dystrophies (LGMD), caused by mutations in sarcoglycan genes. They usually have a childhood onset and rapidly progressive course with loss of ability to walk over 12–16 years. Methods: Next generation sequencing (NGS) targeted gene panel was performed in three adult patients with progressive muscle weakness in which routine muscle histology and immunohistochemistry were not diagnostic. Results: Genetic analysis revealed homozygous or compound heterozygous mutations in SGCA gene and Western Blot demonstrated protein reduction confirming the diagnosis of α-sarcoglicanopathy. Discussion: Our cases evidence that the diagnosis of mild forms of alfa sarcoglicanopathy could be a challenge and suggest the possibility that they could be underdiagnosed. The use of Next generation Sequencing targeted gene panels is very helpful in the diagnosis of these patients.

Sarcoglycanopathies: Clinical, Molecular and Genetic Characteristics, Epidemiology, Diagnostics and Treatment Options

Sarcoglycanopathies are a group of autosomal recessive limb-girdle muscular dystrophies (LGMD) caused by mutations in sarcoglycan genes: SGCA (LGMD 2D, MIM 600119), SGCB (LGMD 2E, MIM 604286), SGCG (LGMD 2C, MIM 353700), and SGCD (LGMD 2F, MIM 601287). These genes encode four transmembrane sarcoglycan subunits participating in formation of the large sarcolemmal dystrophin- glycoprotein complex. Clinical symptoms of sarcoglycanopathies resemble the ones in Duchenne/Becker muscular dystrophy and several autosomal recessive LGMD, which causes difficulties in the differential diagnostics between these diseases. This review covers the main aspects of sarcoglycanopathies, such as etiology, spectrum of mutations, clinical features and diagnostics. In addition, we review the fundamental pathogenesis mechanisms leading to sarcoglycanopathies, which can also help to understand the potential options for treatment for patients with muscular dystrophies.

BNSU SURVEILLANCE PROJECT: MYOCLONUS DYSTONIA SYNDROME

BackgroundMyoclonus Dystonia Syndrome (MDS) is a childhood onset, alcohol responsive movement disorder characterised by trunk and upper limb myoclonus and dystonia of the neck and hands. Inheritance is autosomal dominant...

Phenotypic and immunohistochemical characterization of sarcoglycanopathies

INTRODUCTION:Limb-girdle muscular dystrophy presents with heterogeneous clinical and molecular features. The primary characteristic of this disorder is proximal muscular weakness with variable age of onset, speed of progression, and intensity of symptoms. Sarcoglycanopathies, which are a subgroup of the limb-girdle muscular dystrophies, are caused by mutations in sarcoglycan genes. Mutations in these genes cause secondary deficiencies in other proteins, due to the instability of the dystrophin-glycoprotein complex. Therefore, determining the etiology of a given sarcoglycanopathy requires costly and occasionally inaccessible molecular methods.OBJECTIVE:The aim of this study was to identify phenotypic differences among limb-girdle muscular dystrophy patients who were grouped according to the immunohistochemical phenotypes for the four sarcoglycans.METHODS:To identify phenotypic differences among patients with different types of sarcoglycanopathies, a questionnaire was used and the muscle strength and range of motion of nine joints in 45 patients recruited from the Department of Neurology – HC-FMUSP (Clinics Hospital of the Faculty of Medicine of the University of São Paulo) were evaluated. The findings obtained from these analyses were compared with the results of the immunohistochemical findings.RESULTS:The patients were divided into the following groups based on the immunohistochemical findings: α-sarcoglycanopathies (16 patients), β-sarcoglycanopathies (1 patient), γ-sarcoglycanopathies (5 patients), and non-sarcoglycanopathies (23 patients). The muscle strength analysis revealed significant differences for both upper and lower limb muscles, particularly the shoulder and hip muscles, as expected. No pattern of joint contractures was found among the four groups analyzed, even within the same family. However, a high frequency of tiptoe gait was observed in patients with α-sarcoglycanopathies, while calf pseudo-hypertrophy was most common in patients with non-sarcoglycanopathies. The α-sarcoglycanopathy patients presented with more severe muscle weakness than did γ-sarcoglycanopathy patients.CONCLUSION:The clinical differences observed in this study, which were associated with the immunohistochemical findings, may help to prioritize the mutational investigation of sarcoglycan genes.

Spectrum of mutations in sarcoglycan genes in the Mumbai region of western India: High prevalence of 525del T

While the clinical and immunocytochemical features of sarcoglycanopathies have been reported from India, genetic aspects have not been studied. There is large variation in the sarcoglycan mutations among the studied populations. To study the spectrum of mutations in sarcoglycan genes (SG). Patients fulfilling Bushby's criteria for limb girdle muscular dystrophy were prospectively analyzed. Patients gave their medical history and underwent a clinical examination, serum creatine kinase estimation, electrophysiology, muscle biopsy with immunostaining for alpha, beta, gamma, and delta subunits and mutational analysis using denaturing high pressure liquid chromatography and direct sequencing. Mutations in SG accounted for 26.4% of the cohort of limb girdle muscular dystrophy. The mean age of these 18 patients was 22.5 years. Generally, proximal weakness affected the flexor and adductor compartments of the lower and upper limbs. The clinical profile of various mutations was indistinguishable from each other. Gamma SG mutations were most common, seen in 8 patients, followed by delta SG mutation in 5 patients and alpha mutation in 4 patients, while only 1 patient had mutation in the beta sarcoglycan gene. The most prevalent mutation in the gamma SG gene was 525del T. This is of interest as the mutation has been known to exist only in specific populations. This study, the first mutational analysis of Indian patients with sarcoglycanopathies suggests gamma SG mutations were the most common and the most prevalent mutation in the gamma SG gene was 525del T.

Smooth muscle cell-extrinsic vascular spasm arises from cardiomyocyte degeneration in sarcoglycan-deficient cardiomyopathy.

Vascular spasm is a poorly understood but critical biomedical process because it can acutely reduce blood supply and tissue oxygenation. Cardiomyopathy in mice lacking gamma-sarcoglycan or delta-sarcoglycan is characterized by focal damage. In the heart, sarcoglycan gene mutations produce regional defects in membrane permeability and focal degeneration, and it was hypothesized that vascular spasm was responsible for this focal necrosis. Supporting this notion, vascular spasm was noted in coronary arteries, and disruption of the sarcoglycan complex was observed in vascular smooth muscle providing a molecular mechanism for spasm. Using a transgene rescue strategy in the background of sarcoglycan-null mice, we replaced cardiomyocyte sarcoglycan expression. Cardiomyocyte-specific sarcoglycan expression was sufficient to correct cardiac focal degeneration. Intriguingly, successful restoration of the cardiomyocyte sarcoglycan complex also eliminated coronary artery vascular spasm, while restoration of smooth muscle sarcoglycan in the background of sarcoglycan-null alleles did not. This mechanism, whereby tissue damage leads to vascular spasm, can be partially corrected by NO synthase inhibitors. Therefore, we propose that cytokine release from damaged cardiomyocytes can feed back to produce vascular spasm. Moreover, vascular spasm feeds forward to produce additional cardiac damage.

Limb girdle muscular dystrophy: use of dHPLC and direct sequencing to detect sarcoglycan gene mutations in a New Zealand cohort

Limb girdle muscular dystrophy: use of dHPLC and direct sequencing to detect sarcoglycan gene mutations in a New Zealand cohort

LGMD2E patients risk developing dilated cardiomyopathy

Sarcoglycan gene mutations cause various limb-girdle muscular dystrophies. The sarcoglycans are expressed both in skeletal and cardiac muscle but, surprisingly, so far only a few sarcoglycanopathy patients have had documented cardiomyopathy. We studied six patients with β-sarcoglycanopathy. Immunohistochemical and immunoblot analysis performed on skeletal muscle biopsies from five patients, showed the loss of all sarcoglycans in three cases and marked reduction in two patients. Non-invasive cardiac examinations revealed that three patients had cardiac involvement: one had a severe Duchenne-like dystrophy, lethal dilated cardiomyopathy, and shared the same mutation reported in another cardiomyopathic patient; the other two patients had limb-girdle dystrophy and moderate cardiac involvement (one of them has a novel gene mutation). Given the age profile of the patients studied, the 50% cardiac involvement found in our LGMD2E patients is likely to be a conservative estimate. Careful cardiac monitoring should be carried out in β-sarcoglycanopathy patients who are at high risk of developing cardiomyopathy.

Zeta-sarcoglycan, a novel component of the sarcoglycan complex, is reduced in muscular dystrophy.

The dystrophin glycoprotein complex (DGC) is found at the plasma membrane of muscle cells, where it provides a link between the cytoskeleton and the extracellular matrix. A subcomplex within the DGC, the sarcoglycan complex, associates with dystrophin and mediates muscle membrane stability. Mutations in sarcoglycan genes lead to muscular dystrophy and cardiomyopathy in both humans and mice. In invertebrates, there are three sarcoglycan genes, while in mammals there are additional sarcoglycan genes that probably arose from gene duplication events. We identified a novel mammalian sarcoglycan, zeta-sarcoglycan, that is highly related to gamma-sarcoglycan and delta-sarcoglycan. We generated a zeta-sarcoglycan-specific antibody and found that zeta-sarcoglycan associated with other members of the sarcoglycan complex at the plasma membrane. Additionally, zeta-sarcoglycan was reduced at the membrane in muscular dystrophy, consistent with a role in mediating membrane stability. zeta-Sarcoglycan was also found as a component of the vascular smooth muscle sarcoglycan complex. Together, these data demonstrate that zeta-sarcoglycan is an integral component of the sarcoglycan complex and, as such, is important in the pathogenesis of muscular dystrophy.

Private beta- and gamma-sarcoglycan gene mutations: evidence of a founder effect in Northern Italy.

Autosomal recessive muscular dystrophies called "sarcoglycanopathies" result from mutations in the genes encoding alpha-, beta-, gamma-, or delta-sarcoglycan complex components. The present study involved six unrelated families from Northern Italy showing mutations in the beta- or gamma-sarcoglycan genes. An 8 bp duplication in the beta-sarcoglycan gene and 1 bp insertion in the gamma-sarcoglycan gene occur with high frequency in our population. These mutations have never been reported thus far in other countries. Many patients are homozygotes for a single mutation, although they derived from non-consanguineous marriages. We suggest that these alleles are "private" mutations of this geographical region. A panel of highly informative microsatellite markers that map in the beta- and gamma-sarcoglycan gene locus was used to assess the haplotypes among affected patients and control population, in order to test the presence of linkage disequilibrium. We found that the 8 bp duplication in the beta-sarcoglycan gene and the 1 bp insertion in the gamma-sarcoglycan gene are in linkage disequilibrium with neighbouring polymorphisms. The recurrence of specific sarcoglycan mutations in Northern Italy is probably due to a founder effect, combined with a relative genetic isolation.

Heart involvement in muscular dystrophies due to sarcoglycan gene mutations.

Mutations in the sarcoglycan genes cause autosomal-recessive muscular dystrophies. Because sarcoglycan genes and their protein products are highly expressed both in skeletal and cardiac muscle, patients with these mutations might be expected to be at risk to develop dilated cardiomyopathy. We therefore studied 13 patients with alpha-, beta-, gamma-sarcoglycan gene mutations by thorough cardiological assessment. Electrocardiographic or echocardiographic abnormalities were observed in about 30% of cases showing a severe course of muscular dystrophy. No correlation was found between the presence of cardiac abnormalities and the type of mutation or sarcoglycan gene involved. The cardiac involvement was never severe, but it may be detected in early stages of the muscle disease. The absence of overt cardiac dysfunction may be due to lower sarcoglycan protein expression in cardiac than skeletal muscle or to less sarcolemmal instability at the myocardial level, possibly related to the different distribution of forces generated by contraction of the myocardium with respect to proximal limb-girdle muscles.

The sarcoglycan complex in limb-girdle muscular dystrophy.

The involvement of the sarcoglycan complex in the pathogenesis of muscular dystrophy is becoming increasingly clear. Sarcoglycan gene mutations lead to four forms of autosomal recessive limb-girdle muscular dystrophy. Recent progress has been made with the identification of novel mutations and their correlations with disease. Through this research, a better understanding the molecular pathogenesis of limb-girdle muscular dystrophy has been gained. Finally, animal models are now being used to study viral-mediated gene transfer for the future treatment of this disease.

From dystrophinopathy to sarcoglycanopathy: Evolution of a concept of muscular dystrophy

Duchenne and Becker muscular dystrophies are collectively termed dystrophinopathy. Dystrophinopathy and severe childhood autosomal recessive muscular dystrophy (SCARMD) are clinically very similar and had not been distinguished in the early 20th century. SCARMD was first classified separately from dystrophinopathy due to differences in the mode of inheritance. Studies performed several years ago clarified some immunohistochemical and genetic characteristics of SCARMD, but many remained to be clarified. In 1994, the sarcoglycan complex was discovered among dystrophin-associated proteins. Subsequently, on the basis of our immunohistochemical findings which indicated that all components of the sarcoglycan complex are absent in SCARMD muscles, and the previous genetic findings, we proposed that a mutation of any one of the sarcoglycan genes leads to SCARMD. This hypothesis explained and predicted various characteristics of SCARMD at the molecular level, most of which have been verified by subsequent discoveries in our own as well as various other laboratories. SCARMD is now called sarcoglycanopathy, which is caused by a defect of any one of four different sarcoglycan genes, and thus far mutations in sarcoglycan genes have been documented in the SCARMD patients. In this review, the evolution of the concept of sarcoglycanopathy separate from that of dystrophinopathy is explained by comparing studies on these diseases. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:421–438, 1998.

From dystrophinopathy to sarcoglycanopathy: evolution of a concept of muscular dystrophy.

Duchenne and Becker muscular dystrophies are collectively termed dystrophinopathy. Dystrophinopathy and severe childhood autosomal recessive muscular dystrophy (SCARMD) are clinically very similar and had not been distinguished in the early 20th century. SCARMD was first classified separately from dystrophinopathy due to differences in the mode of inheritance. Studies performed several years ago clarified some immunohistochemical and genetic characteristics of SCARMD, but many remained to be clarified. In 1994, the sarcoglycan complex was discovered among dystrophin-associated proteins. Subsequently, on the basis of our immunohistochemical findings which indicated that all components of the sarcoglycan complex are absent in SCARMD muscles, and the previous genetic findings, we proposed that a mutation of any one of the sarcoglycan genes leads to SCARMD. This hypothesis explained and predicted various characteristics of SCARMD at the molecular level, most of which have been verified by subsequent discoveries in our own as well as various other laboratories. SCARMD is now called sarcoglycanopathy, which is caused by a defect of any one of four different sarcoglycan genes, and thus far mutations in sarcoglycan genes have been documented in the SCARMD patients. In this review, the evolution of the concept of sarcoglycanopathy separate from that of dystrophinopathy is explained by comparing studies on these diseases.

Human ϵ-sarcoglycan is highly related to α-sarcoglycan (adhalin), the limb girdle muscular dystrophy 2D gene

The dystrophin-glycoprotein complex (DGC) is critical for muscle membrane stability. The sarcoglycans are transmembrane proteins within the DGC, and the function of the sarcoglycans is unknown. Mutations in sarcoglycan genes cause autosomal recessive muscular dystrophy. We have identified a new sarcoglycan gene with high homology to α-sarcoglycan highlighting the redundancy of the DGC. This gene, named ϵ-sarcoglycan, has an identical intron-exon structure to α-sarcoglycan, and is more broadly expressed. The characterization of ϵ-sarcoglycan should make it possible to determine if it, like the other sarcoglycan genes, is mutated in muscular dystrophy.

Genetic epidemiology of muscular dystrophies resulting from sarcoglycan gene mutations.

BACKGROUND: The autosomal recessive limb-girdle muscular dystrophies (LGMDs) are a group of genetically heterogeneous muscle diseases characterised by progressive proximal limb muscle weakness. Six different loci have been mapped and...

Known and novel sarcoglycan gene mutations in Portuguese patients

Known and novel sarcoglycan gene mutations in Portuguese patients