Myoclonus-dystonia Syndrome Research Articles

Incomplete nonsense‐mediated decay facilitates detection of a multi‐exonic deletion mutation in SGCE

Mutations in SGCE represent the major cause of the myoclonus-dystonia syndrome (DYT11), an autosomal dominant disorder of reduced penetrance. Virtually all affected individuals have myoclonus, which is concentrated in the upper extremities, neck and trunk. Over half of patients have dystonia, usually affecting the neck or arms. SGCE is maternally imprinted. Of the more than 70 SGCE mutations reported in the literature, 18 are large deletions disrupting at least one exon. Therefore, testing for exonic deletions should be considered in individuals with a classic phenotype in whom Sanger sequencing is unrevealing. However, standard methodologies for detection of exonic deletion mutations are expensive, labor intensive and can produce false negatives. Herein, we report the use of cDNA derived from leukocyte RNA to identify a deletion mutation (exons 4 and 5) of SGCE in a family with DYT11. Residual RNA from incomplete nonsense-mediated decay permitted reverse transcription to cDNA. Breakpoints of the 8939 bp heterozygous deletion were then defined with long-range polymerase chain reaction and Sanger sequencing. Use of cDNA generated by reverse transcription of leukocyte RNA can reduce the costs associated with diagnostic genetic testing and can facilitate detection of deletion mutations.

Effects of Denosumab on 1/3 Radius Bone Mineral Density in Postmenopausal Women Across Randomized Controlled Clinical Trials

Loss-of-function mutations in SGCE, which encodes ε-sarcoglycan (ε-SG), cause myoclonus-dystonia syndrome (OMIM159900, DYT11). A “major” ε-SG protein derived from CCDS5637.1 (NM_003919.2) and a “brain-specific” protein, that includes sequence derived from alternative exon 11b (CCDS47642.1, NM_001099400.1), are reportedly localized in post- and pre-synaptic membrane fractions, respectively. Moreover, deficiency of the “brain-specific” isoform and other isoforms derived from exon 11b may be central to the pathogenesis of DYT11. However, no animal model supports this hypothesis. Gene-trapped ES cells (CMHD-GT_148G1-3, intron 9 of NM_011360) were used to generate a novel Sgce mouse model (C57BL/6J background) with markedly reduced expression of isoforms derived from exons 3′ to exon 9 of NM_011360. Among those brain regions analyzed in adult (2 month-old) wild-type (WT) mice, cerebellum showed the highest relative expression of isoforms incorporating exon 11b. Homozygotes (SgceGt(148G1)Cmhd/Gt(148G1)Cmhd or SgceGt/Gt) and paternal heterozygotes (Sgcem+/pGt, m-maternal, p-paternal) showed 60 to 70% reductions in expression of total Sgce. Although expression of the major (NM_011360) and brain-specific (NM_001130189) isoforms was markedly reduced, expression of short isoforms was preserved and relatively small amounts of chimeric ε-SG/β-galactosidase fusion protein was produced by the Sgce gene-trap locus. Immunoaffinity purification followed by mass spectrometry assessments of Sgcem+/pGt mouse brain using pan- or brain-specific ε-SG antibodies revealed significant reductions of ε-SG and other interacting sarcoglycans. Genome-wide gene-expression data using RNA derived from adult Sgcem+/pGt mouse cerebellum showed that the top up-regulated genes were involved in cell cycle, cellular development, cell death and survival, while the top down-regulated genes were associated with protein synthesis, cellular development, and cell death and survival. In comparison to WT littermates, Sgcem+/pGt mice exhibited “tiptoe” gait and stimulus-induced appendicular posturing between Postnatal Days 14 to 16. Abnormalities noted in older Sgcem+/pGt mice included reduced body weight, altered gait dynamics, and reduced open-field activity. Overt spontaneous or stimulus-sensitive myoclonus was not apparent on the C57BL/6J background or mixed C57BL/6J-BALB/c and C57BL/6J-129S2 backgrounds. Our data confirm that mouse Sgce is a maternally imprinted gene and suggests that short Sgce isoforms may compensate, in part, for deficiency of major and brain-specific Sgce isoforms.

Myoclonus-dystonia syndrome due to tyrosine hydroxylase deficiency

To present a new family with tyrosine hydroxylase deficiency (THD) that presented with a new phenotype of predominant, levodopa-responsive myoclonus with dystonia due to compound heterozygosity of one previously reported mutation in the promoter region and a novel nonsynonymous mutation in the other allele, thus expanding the clinical and genetic spectrum of this disorder. We performed detailed clinical examination of the family and electrophysiology to characterize the myoclonus. We performed analysis of the TH gene and in silico prediction of the possible effect of nonsynonymous substitutions on protein structure. Electrophysiology suggested that the myoclonus was of subcortical origin. Genetic analysis of the TH gene revealed compound heterozygosity of a point mutation in the promoter region (c.1-71 C>T) and a novel nonsynonymous substitution in exon 12 (c.1282G>A, p.Gly428Arg). The latter is a novel variant, predicted to have a deleterious effect on the TH protein function and is the first pathogenic TH mutation in patients of African ancestry. We presented a THD family with predominant myoclonus-dystonia and a new genotype. It is important to consider THD in the differential diagnosis of myoclonus-dystonia, because early treatment with levodopa is crucial for these patients.

Alteration of Striatal Dopaminergic Neurotransmission in a Mouse Model of DYT11 Myoclonus-Dystonia

BackgroundDYT11 myoclonus-dystonia (M-D) syndrome is a neurological movement disorder characterized by myoclonic jerks and dystonic postures or movement that can be alleviated by alcohol. It is caused by mutations in SGCE encoding ε-sarcoglycan (ε-SG); the mouse homolog of this gene is Sgce. Paternally-inherited Sgce heterozygous knockout (Sgce KO) mice exhibit myoclonus, motor impairment and anxiety- and depression-like behaviors, modeling several clinical symptoms observed in DYT11 M-D patients. The behavioral deficits are accompanied by abnormally high levels of dopamine and its metabolites in the striatum of Sgce KO mice. Neuroimaging studies of DYT11 M-D patients show reduced dopamine D2 receptor (D2R) availability, although the possibility of increased endogenous dopamine, and consequently, competitive D2R occupancy cannot be ruled out.Methodology/Principal FindingsThe protein levels of striatal D2R, dopamine transporter (DAT), and dopamine D1 receptor (D1R) in Sgce KO mice were analyzed by Western blot. The striatal dopamine release after amphetamine injection in Sgce KO mice were analyzed by microdialysis in vivo. The striatal D2R was significantly decreased in Sgce KO mice without altering DAT and D1R. Sgce KO mice also exhibited a significant increase of dopamine release after amphetamine injection in comparison to wild-type (WT) littermates.Conclusion/SignificanceThe results suggest ε-SG may have a role in the regulation of D2R expression. The loss of ε-SG results in decreased striatal D2R, and subsequently leads to increased discharge of dopamine which could contribute to the behavioral impairment observed in DYT11 dystonia patients and in Sgce KO mice. The results suggest that reduction of striatal D2R and enhanced striatal dopamine release may contribute to the pathophysiology of DYT11 M-D patients.

1624 Myoclonus dystonia: a clinical and genetic description

BackgroundMyoclonus Dystonia Syndrome (MDS) is a childhood onset movement disorder involving trunk and upper limb myoclonus and dystonia of the neck and hands. Psychiatric co-morbidity has also been described and...

A Novel Mutation in Exon 6 of the Epsilon-Sarcoglycan Gene in Myoclonus Dystonia Syndrome

Abstract Myoclonus-dystonia syndrome (MDS) is a rare hereditary movement disorder characterized by the early onset of myoclonus in the first or second decade of life. The first locus for MDS was mapped to chromosome 7q21 and identified as the epsilon-sarcoglycan (SGCE) gene, and numerous mutations were subsequently identified. We here present the first reported Turkish MDS patient identified with a novel mutation in exon 6 of the SGCE gene, which resulted in truncation of the protein before the transmembrane domain, presumably causing the loss of function either by mislocalization of the protein away from the plasma membrane or through nonsense-mediated decay.

A gain-of-glycosylation mutation associated with myoclonus-dystonia syndrome affects trafficking and processing of mouse ε-sarcoglycan in the late secretory pathway

Missense mutations in the SGCE gene encoding ε-sarcoglycan account for approximately 15% of SGCE-positive cases of myoclonus-dystonia syndrome (MDS) in humans. In this study, we show that while the majority of MDS-associated missense mutants modeled with a murine ε-sarcoglycan cDNA are substrates for endoplasmic reticulum-associated degradation, one mutant, M68T (analogous to human c.275T>C, p.M92T), located in the Ig-like domain of ε-sarcoglycan, results in a gain-of-glycosylation mutation producing a protein that is targeted to the plasma membrane, albeit at reduced levels compared to wild-type ε-sarcoglycan. Removal of the ectopic N-linked glycan failed to restore efficient plasma membrane targeting of M68T demonstrating that the substitution rather than the glycan was responsible for the trafficking defect of this mutant. M68T also colocalized with CD63-positive vesicles in the endosomal-lysosomal system and was found to be more susceptible to lysosomal proteolysis than wild-type ε-sarcoglycan. Finally, we demonstrate impaired ectodomain shedding of M68T, a process that occurs physiologically for ε-sarcoglycan resulting in the lysosomal trafficking of the intracellular C-terminal domain of the protein. Our findings show that functional analysis of rare missense mutations can provide a mechanistic insight into the pathogenesis of MDS and the physiological role of ε-sarcoglycan.

DYT 11 Myoclonus-Dystonia Syndrome (MDS) with generalized epileptic discharges

We report on an 11 year old boy with a mutation in the Epsilon-Sarcoglycan (SGCE) gene associated with familial DYT 11 myoclonus-dystonia syndrome (MDS). At the age of 2 years he initially presented with a movement disorder by gait disturbance with inward rotation of both legs. Adiotionally the patient suffered from multifocal myoclonus affecting both arms, the upper part of the body and the head with a frequency of 100 a day over a period of 10 seconds remaining difficulties with eating and writing from the age of 6 years. In the absence of myoclonus or long repetitive jerks continous EEG videomonitoring showed epileptic activity: generalized (maximum electrode F4 and F3, 55%), left frontal (maximum electrode F3, 30%), right frontal (maximum electrode F4, 12,5%) and right parietal (maximum electrode P8, 2,5%). Meanwhile, epileptic EEG-activity during myoclonus was not seen.

A novel mutation of the SGCE-gene in a German family with myoclonus-dystonia syndrome

Here we describe the clinical and genetic findings of a 40 year old female patient and her 2-years-younger sister (Fig. 1, probands III:1 and III:2) suffering from myoclonus-dystonia syndrome (MDS) with a novel missense mutation in the gene encoding e-sarcoglycan (SGCE), which inhibits the expression of exon 4 and leads to a truncated and, therefore, inactive protein. MDS is an autosomal-dominant inherited disease characterized by a combination of dystonia and myoclonic jerks that frequently respond to ethanol ingestion [1]. Additional non-motor symptoms like anxiety and panic attacks, obsessive–compulsive symptoms, or addiction may coexist. In many cases, mutations in the SGCE-gene have been proven to cause the disease [2]. The two sisters experienced progressive symptoms of dystonia combined with myoclonic features in both lower extremities since the age of 1 year. While the older patient developed additional myoclonic jerks of the head as well as of both arms, particularly during action, the symptoms of her sister were less severe and limited to the lower extremities and the trunk (online resource 1 and 2). No other member of the family was affected (Fig. 1). The patients never suffered from seizures or psychiatric diseases. Cranial MRI, MEP, SSEP, and EEG were normal. Laboratory testing of spinal fluid, urine, and blood did not provide any hints for immunological or metabolic diseases. After extraction and sequencing of the patients’ and their father’s (Fig. 1, proband II:1) DNA, a novel heterozygote point mutation with a substitution of guanosine against adenosine at the last position of exon 4 (c.463G[A) was detected in both patients and their father (Fig. 2a). Different software algorithms suggested a high chance for an aberrant splicing, and thus, the presence of a translationally relevant mutation. This prediction was confirmed with the electrophoresis of the probands’ RT–PCR products on an agarose gel, which revealed a shortened RT– PCR product for both sisters, but not for the father. Sequencing of the short RT–PCR fragment confirmed that the sequence of exon 3 was followed by the sequence of exon 5 (Fig. 2b). The phenomenon of the missing exon 4 in the cDNA had to be due to aberrant splicing, because the coding strand of the sisters’ DNA contained the nucleotide sequence of all exons. As the DNA sequence of exon 4 consists of 73 nucleotides, this aberrant splicing did not only cause a deletion of relevant nucleotides [3, 4], but also predicted to result in an inactive protein due to a frame shift and a stop after 14 amino acids (p.I131TfsX15). In contrast to the findings in both sisters, the RT–PCR product of the father had a regular sequence. Electronic supplementary material The online version of this article (doi:10.1007/s00415-011-5911-6) contains supplementary material, which is available to authorized users.

POMD10 Do psychiatric disorders form part of the myoclonus-dystonia syndrome phenotype? A systematic review of published literature

Myoclonus–dystonia syndrome (MDS) is a rare movement disorder characterised by myoclonus mainly of the trunk and upper limbs in conjunction with dystonic posturing, usually of neck and hands. Mutations of...

Large SGCE deletion contributes to Taiwanese myoclonus–dystonia syndrome

We report three novel deletions of the SGCE gene in three families with myoclonus–dystonia (M–D) syndrome in Taiwan. Their clinical characteristics included: early onset, dominant myoclonus and dystonia in the neck, trunk and upper limbs. By direct sequencing of the SGCE gene coding regions, we identified a small heterozygous deletion (c.842delA) in exon 7 of the three sibs and asymptomatic father in the first family and an eight-base heterozygous deletion (c.524_531del) in exon 5 of the mother and a daughter in the second family. Using multiple ligation-dependent probe amplification (MLPA), a large heterozygous deletion of 2–11 exons was identified in the father and a son in the third family which was undetected by initial sequencing. It is the largest intragenic deletion ever reported. In conclusion, we have identified three novel mutations of SGCE in the respective three M–D families. The large deletion was responsible for one third of these M–D families which might implicate an important contribution to Taiwanese M–D syndrome. We suggest that the contribution of large deletion should be further verified in a large cohort of patients with M–D syndrome in Han Chinese.

Atypical Silver–Russell phenotype resulting from maternal uniparental disomy of chromosome 7

We report on a patient with atypical Silver-Russell phenotype comprising severe growth retardation, unusual facies, bilateral Duane anomaly and infantile hypercalcemia caused by maternal uniparental iso/heterodisomy (mUPD) of chromosome 7. The development of myoclonus in this patient lends further support to the hypothesis that abnormal imprinting of the SGCE gene is responsible for some cases of myoclonus-dystonia syndrome. This case highlights the utility of SNP microarray technology as an accessible tool for the diagnosis of mUPD7 in atypical cases. We propose that depending on the balance of iso- and heterodisomic segments in a particular patient, mUPD7 may result in a range of phenotypes not confined to classic Silver-Russell syndrome.

Excellent response to oral zolpidem in a sporadic case of the myoclonus dystonia syndrome

Excellent response to oral zolpidem in a sporadic case of the myoclonus dystonia syndrome

Bilateral pallidal deep brain stimulation in a case of myoclonus dystonia syndrome

Bilateral pallidal deep brain stimulation in a case of myoclonus dystonia syndrome

The neurobiology of the dystrophin-associated glycoprotein complex

While the function of dystrophin in muscle disease has been thoroughly investigated, dystrophin and associated proteins also have important roles in the central nervous system. Many patients with Duchenne and Becker muscular dystrophies (D/BMD) have cognitive impairment, learning disability, and an increased incidence of some neuropsychiatric disorders. Accordingly, dystrophin and members of the dystrophin-associated glycoprotein complex (DGC) are found in the brain where they participate in macromolecular assemblies that anchor receptors to specialized sites within the membrane. In neurons, dystrophin and the DGC participate in the postsynaptic clustering and stabilization of some inhibitory GABAergic synapses. During development, α-dystroglycan functions as an extracellular matrix receptor controlling, amongst other things, neuronal migration in the developing cortex and cerebellum. Several types of congenital muscular dystrophy caused by impaired α-dystroglycan glycosylation cause neuronal migration abnormalities and mental retardation. In glial cells, the DGC is involved in the organization of protein complexes that target water-channels to the plasma membrane. Finally, mutations in the gene encoding ε-sarcoglycan cause the neurogenic movement disorder, myoclonus-dystonia syndrome implicating ε–sarcoglycan in dopaminergic neurotransmission. In this review we describe the recent progress in defining the role of the DGC and associated proteins in the brain.

Myoclonus and tremor response to thalamic deep brain stimulation parameters in a patient with inherited myoclonus–dystonia syndrome

We present a 74-year-old woman with inherited myoclonus–dystonia, with predominant myoclonus and a novel mutation in the ɛ-sarcoglycan gene. The patient reports a life-long history of rapid, jerking movements, most severe in the upper extremities as well as a postural and action tremor. Bilateral deep brain stimulation (DBS) of the ventral intermediate nucleus of the thalamus was performed, and the patient demonstrated moderate clinical improvement in myoclonus. We studied the effects on myoclonus and tremor of varying DBS frequency and amplitude. The frequency tuning curve for myoclonus was similar to that of tremor, suggesting similar mechanisms by which DBS alleviates both disorders.

Myoclonus-Dystonia Due to Maternal Uniparental Disomy

Myoclonus-dystonia is a movement disorder often associated with mutations in the maternally imprinted epsilon-sarcoglycan (SGCE) gene located on chromosome 7q21. Silver-Russell syndrome is a heterogeneous disorder characterized by prenatal and postnatal growth restriction and a characteristic facies, caused in some cases by maternal uniparental disomy of chromosome 7. To describe and investigate the combination of a typical myoclonus-dystonia syndrome and Silver-Russell syndrome. Clinical and neurophysiological examination as well as cytogenetic and molecular analyses. Movement disorder clinic. Patient A 36-year-old man with typical myoclonus-dystonia and Silver-Russell syndrome. Clinical description of the disease and its genetic cause. Cytogenetic analysis revealed mosaicism for a small chromosome 7 marker chromosome. Microsatellite analysis indicated loss of the paternal allele and maternal uniparental disomy of chromosome 7. In keeping with the maternal imprinting mechanism, no unmethylated allele of SGCE was detected after bisulfite treatment of the patient's DNA, and reverse transcription-polymerase chain reaction demonstrated loss of SGCE expression. Molecular analysis ruled out mutations in the SGCE gene. We identified a new genetic alteration-maternal chromosome 7 disomy-that can cause myoclonus-dystonia. This alteration results in repression of both alleles of the maternally imprinted SGCE gene and suggests SGCE loss of function as the disease mechanism.

A neurophysiological study of myoclonus in patients with DYT11 myoclonus‐dystonia syndrome

Mutations in the epsilon-sarcoglycan (SGCE) gene have been associated with DYT11 myoclonus-dystonia syndrome (MDS). The aim of this study was to characterize myoclonus in 9 patients with DYT11-MDS presenting with predominant myoclonus and mild dystonia by means of neurophysiological techniques. Variously severe multifocal myoclonus occurred in all of the patients, and included short (mean 89.1 +/- 13.3 milliseconds) electromyographic bursts without any electroencephalographic correlate, sometimes presenting a pseudo-rhythmic course. Massive jerks could be evoked by sudden stimuli in 5 patients, showing a "startle-like" muscle spreading and latencies consistent with a brainstem origin. Somatosensory evoked potentials and long-loop reflexes were normal, as was silent period and long-term intracortical inhibition evaluated by means of transcranial magnetic stimulation; however, short-term intracortical inhibition revealed subtle impairment, and event-related synchronization (ERS) in the beta band was delayed. Blink reflex recovery was strongly enhanced. Myoclonus in DYT11-MDS seems to be generated at subcortical level, and possibly involves basal ganglia and brainstem circuitries. Cortical impairment may depend from subcortical dysfunction, but it can also have a role in influencing the myoclonic presentation. The wide distribution of the defective SCGE in DYT11-MDS may justify the involvement of different brain areas.

Impact of Medicare Cutbacks In DXA Reimbursement on Care of Patients At Risk For Fracture

Loss-of-function mutations in SGCE, which encodes ε-sarcoglycan (ε-SG), cause myoclonus-dystonia syndrome (OMIM159900, DYT11). A “major” ε-SG protein derived from CCDS5637.1 (NM_003919.2) and a “brain-specific” protein, that includes sequence derived from alternative exon 11b (CCDS47642.1, NM_001099400.1), are reportedly localized in post- and pre-synaptic membrane fractions, respectively. Moreover, deficiency of the “brain-specific” isoform and other isoforms derived from exon 11b may be central to the pathogenesis of DYT11. However, no animal model supports this hypothesis. Gene-trapped ES cells (CMHD-GT_148G1-3, intron 9 of NM_011360) were used to generate a novel Sgce mouse model (C57BL/6J background) with markedly reduced expression of isoforms derived from exons 3′ to exon 9 of NM_011360. Among those brain regions analyzed in adult (2 month-old) wild-type (WT) mice, cerebellum showed the highest relative expression of isoforms incorporating exon 11b. Homozygotes (SgceGt(148G1)Cmhd/Gt(148G1)Cmhd or SgceGt/Gt) and paternal heterozygotes (Sgcem+/pGt, m-maternal, p-paternal) showed 60 to 70% reductions in expression of total Sgce. Although expression of the major (NM_011360) and brain-specific (NM_001130189) isoforms was markedly reduced, expression of short isoforms was preserved and relatively small amounts of chimeric ε-SG/β-galactosidase fusion protein was produced by the Sgce gene-trap locus. Immunoaffinity purification followed by mass spectrometry assessments of Sgcem+/pGt mouse brain using pan- or brain-specific ε-SG antibodies revealed significant reductions of ε-SG and other interacting sarcoglycans. Genome-wide gene-expression data using RNA derived from adult Sgcem+/pGt mouse cerebellum showed that the top up-regulated genes were involved in cell cycle, cellular development, cell death and survival, while the top down-regulated genes were associated with protein synthesis, cellular development, and cell death and survival. In comparison to WT littermates, Sgcem+/pGt mice exhibited “tiptoe” gait and stimulus-induced appendicular posturing between Postnatal Days 14 to 16. Abnormalities noted in older Sgcem+/pGt mice included reduced body weight, altered gait dynamics, and reduced open-field activity. Overt spontaneous or stimulus-sensitive myoclonus was not apparent on the C57BL/6J background or mixed C57BL/6J-BALB/c and C57BL/6J-129S2 backgrounds. Our data confirm that mouse Sgce is a maternally imprinted gene and suggests that short Sgce isoforms may compensate, in part, for deficiency of major and brain-specific Sgce isoforms.

A novel mutation of the ε‐sarcoglycan gene in a Chinese family with myoclonus‐dystonia syndrome

In a Chinese myoclonus-dystonia syndrome (MDS) family presented with a phenotype including a typical MDS, cervical dystonia, and writer's cramp, genetic analyses revealed a novel 662 + 1insG heterozygous mutation in exon 5 in the epsilon-sarcoglycan (SGCE) gene, leading to a frameshift with a down stream stop codon. Low SGCE mRNA levels were detected in the mutation carriers by real-time PCR, suggesting that the nonsense mutation might interfere with the stability of SGCE mRNA. This is the first report on Chinese with a SGCE mutation leading to MDS. Our data support the fact that same mutation of SGCE gene can lead to a varied phenotype, even in the same family.