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PubMed1990

[A case of flexion myelopathy presenting juvenile segmental muscular atrophy of upper extremities--a successful treatment by cervical spine immobilization].

A 24-year-old man was well until 1982, when he noticed weakness and atrophy of right arm especially those of biceps muscles. These symptoms did not progress until 1988. In 1988 weakness of left elbow flexion appeared and he was admitted to our hospital. On examination, he had weakness and atrophy of both upper extremities. Fasciculation was noticed in the proximal part of right arm. When his head was bent forward, dysesthesia appeared around radial side of his arm. There were no long tract sign or objective sensory loss. EMG showed neurogenic change over both his upper extremities. In plain cervical roentgenogram there existed abnormal kyphosis of cervical vertebrae. In MRI imaged with his neck flexed, cervical cord was compressed by the posterior surface of 4th cervical vertebral body, which corresponded to the top of cervical kyphosis. Based on these signs and examinations, a diagnosis of flexion myelopathy was made. Spinal immobilization by wiring and bone graft implantation ranging from C2 to C6 was performed to limit the range of anterior nuchal flexion. After this operation, improvement of muscle strength along with the disappearance of dysesthesia on neck flexion was observed. Clinically, this case closely resembles to juvenile type of distal and segmental muscular atrophy of upper extremities (Hirayama type). From our study, pathomechanism of this case seems to be a flexion myelopathy at C4 level. This view is supported also by the good recovery after the operation. This case suggests that nonprogressive atrophy of upper extremities due to flexion myelopathy can be successfully treated by cervical spine immobilization.

Adult↗
PubMed1996

Spinocerebellar ataxia type-1 and spinobulbar muscular atrophy gene products interact with glyceraldehyde-3-phosphate dehydrogenase.

Spinocerebellar ataxia type1 (SCA1) is one of several neurodegenerative disorders caused by expansions of translated CAG trinucleotide repeats which code for polyglutamine in the respective proteins. Most hypotheses about the molecular defect in these disorders suggest a gain of function, which may involve interactions with other proteins via the expanded polyglutamine tract. In this study we used ataxin-1, the SCA1 gene product, as a bait in the yeast two-hybrid system and identified the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase as an ataxin-1 interacting protein. In addition, the yeast two hybrid data demonstrate that wild type and mutant ataxin-1 form homo and heterodimers. Physical interaction between GAPDH and ataxin-1 was also demonstrated in vitro. To investigate if GAPDH might interact with other glutamine repeat-containing proteins involved in neurodegenerative disorders, we tested its binding to the androgen receptor which is mutated in spinobulbar muscular atrophy. The androgen receptor interacts with GAPDH both in the yeast two-hybrid system and in vitro. The binding of both ataxin-1 and the androgen receptor to GAPDH does not vary with the length of the polyglutamine tract. While provocative, these findings do not address the selective neuronal loss in each of these disorders in light of the wide expression patterns of GAPDH and the respective polyglutamine containing proteins. Nonetheless, such interactions may increase the susceptibility of specific neurons to a variety of insults and initiate degeneration.

Animals↗
PubMed2001

Hybrids monosomal for human chromosome 5 reveal the presence of a spinal muscular atrophy (SMA) carrier with two SMN1 copies on one chromosome.

We have analyzed the survival motor neuron gene (SMN1) dosage in 100 parents of children with homozygous SMN1 deletions. Of these parents, 96 (96%) demonstrated the expected one-copy SMN1 carrier genotype. However, four parents (4%) were observed to have a normal two-copy SMN1 dosage. The presence of two intact SMN1 genes in the parent of an affected child indicates either the occurrence of a de novo mutation event or a situation in which one chromosome has two copies of SMN1, whereas the other is null. We have separated individual chromosomes from two of these parents with two-copy SMN1 dosage by somatic cell hybridization and have employed a modified quantitative dosage assay to provide direct evidence that one parent is a two-copy/ zero-copy SMN1 carrier, whereas the other parent had an affected child as the result of a de novo mutation. These findings are important for assessing the recurrence risk of parents of children with spinal muscular atrophy and for providing accurate family counseling.

Autoradiography↗
PubMed1999

[An elderly case of juvenile muscular atrophy in the unilateral upper extremity with tremor in both hands].

A 75-year-old man had noticed muscle atrophy and weakness of his right hand and forearm at the age of 25. The symptoms slowly progressed and then stopped. Right hand tremor appeared at about age 40. There was no symptom in his left upper extremity, and his gait was normal. He now shows severe muscle atrophy in his right hand and forearm. There was distally dominant weakness of the right upper extremity and his hand grip was 0 kg on the right and 25 kg on the left. On admission there was no weakness in the bilateral lower extremities. He had postural tremor in both hands and fingers. The tendon reflexes were hypoactive in the upper extremities and normal in the lower extremities. Abnormalities in the superficial sensation were unremarkable, whereas vibration sensation in both the upper and lower extremities was mildly disturbed. Electromyography revealed chronic denervation, especially in the right upper extremity. The sensory nerve conduction study results and somatosensory evoked potentials in the upper extremities were normal. Cervical MRI demonstrated spondylotic changes, canal stenosis from the C5 to C7 levels, and compression of the spinal cord. His hand tremor was dominant on the right with a peak frequency of about 7 Hz. Tremor frequency and power were decreased by mechanical load. Hirayama's disease (juvenile muscular atrophy of unilateral upper extremity) was the most probable diagnosis, although aging might have produced various additional abnormalities. The tremor seen in this patient showed characteristics of enhanced physiological tremor.

Aged↗
PubMed1998

Spinobulbar muscular atrophy: polyglutamine-expanded androgen receptor is proteolytically resistant in vitro and processed abnormally in transfected cells.

The neuronotoxicity of genes with expanded CAG repeats is most likely mediated by their respective polyglutamine (Gln)-expanded gene products. Gln- expanded portions of these products may be sufficient, or necessary, for pathogenesis. We tested whether a Gln-expanded human androgen receptor (AR) is structurally altered, so that it allows for the proteolytic generation of a potentially pathogenic portion that may be resistant to further degradation. We found, in vitro , that a Gln-expanded AR is more proteolytically resistant than normal, and that it yields a distinct set of Gln-expanded fragments even after extended proteolysis in the presence of 2 M urea. Furthermore, COS cells transfected with CAG-expanded AR cDNA generate an aberrant, nuclear-associated 75 kDa derivative containing the Gln-expanded tract. They are also twice as likely to die by 24 h apoptotically than those transfected with normal AR cDNA. Our data support the notion that an unconventional derivative of the Gln- expanded AR is a component of the proximate motor neuronopathic agent in spinobulbar muscular atrophy. They also focus attention on two ways in which neuronotoxic derivatives may originate from various Gln-expanded proteins: (i) generation of an unusual derivative that is pathogenic de novo ; and (ii) the toxic accumulation of a normal derivative because of an inability to dispose of it.

Animals↗
PubMed2003

Chromosomal mapping of the peroneal muscular atrophy (pma) gene in the mouse.

We conducted chromosomal mapping of the pma gene that is a causative gene in the peroneal muscular atrophy mouse, which shows a club foot at birth and unusual gait due to a dropped foot in the adult. Linkage analyses using backcross progeny revealed a significant linkage between the pma gene and three microsatellite markers, D5Mit263 at 73 cM, D5Mit141 and D5Mit97 at 74 cM on Chr 5. The gene order was determined as follows: centromere-D5Mit263-[2.65 cM]-D5Mit141-[2.56 cM]-pma-[5.13 cM]-D5Mit97-telomere.

Animals↗
PubMed1996

YAC contigs of the Rab1 and wobbler (wr) spinal muscular atrophy gene region on proximal mouse chromosome 11 and of the homologous region on human chromosome 2p.

Despite rapid progress in the physical characterization of murine and human genomes, little molecular information is available on certain regions, e.g., proximal mouse chromosome 11 (Chr 11) and human chromosome 2p (Chr 2p). We have localized the wobbler spinal atrophy gene wr to proximal mouse Chr 11, tightly linked to Rab1, a gene coding for a small GTP-binding protein, and Glnsps1, an intronless pseudogene of the glutamine synthetase gene. We have now used these markers to construct a 1.3-Mb yeast artificial chromosome (YAC) contig of the Rab1 region on mouse Chr 11. Four YAC clones isolated from two independent YAC libraries were characterized by rare-cutting analysis, fluorescence in situ hybridization (FISH), and sequence-tagged site (STS) isolation and mapping. Rab1 and Glns-ps1 were found to be only 200 kb apart. A potential CpG island near a methylated NarI site and a trapped exon, ETG1.1, were found between these loci, and a new STS, AHY1.1, was found over 250 kb from Rab1. Two overlapping YACs were identified that contained a 150-kb region of human Chr 2p, comprising the RAB1 locus, AHY1.1, and the human homologue of ETG1.1, indicating a high degree of conservation of this region in the two species. We mapped AHY1.1 and thus human RAB1 on Chr 2p13.4-p14 using somatic cell hybrids and a radiation hybrid panel, thus extending a known region of conserved synteny between mouse Chr 11 and human Chr 2p. Recently, the gene LMGMD2B for a human recessive neuromuscular disease, limb girdle muscular dystrophy type 2B, has been mapped to 2p13-p16. The conservation between the mouse Rab1 and human RAB1 regions will be helpful in identifying candidate genes for the wobbler spinal muscular atrophy and in clarifying a possible relationship between wr and LMGMD2B.

Animals↗
PubMed1992

Peroneal muscular atrophy with hereditary spastic paraparesis (HMSN V) is pathologically heterogeneous. Report of nerve biopsy in four cases and review of the literature.

Peroneal muscular atrophy (PMA) associated with hereditary spastic paraparesis (HSP) is a nosologically ill-defined disease, which has been classified by Dyck as hereditary motor and sensory neuropathy type V (HMSN V). Nerve biopsy has been rarely reported in this condition. We examined sural nerve biopsies in four patients, demonstrating the following: severe myelinated fiber loss especially of large fibers, with moderate (one case) or prominent (one case) onion bulb formation; selective decrease of large fibers with moderate Schwann cell hyperplasia (one case); normal myelinated fiber population with minimal changes (one case). After reviewing previously reported cases we, conclude that in PMA with HSP sural nerve biopsy may show features either of hypertrophic type of PMA, of neuronal type, or of spinal type; thus, it seems inappropriate to allocate PMA with HSP in a unique subtype of HMSN. In addition, HSP may be not associated with peripheral neuropathy, and thus the classification in the HMSN group may be incongruous. A proper classification of PMA with HSP may be in the "complicated" forms of HSP according to Harding [Lancet I: 1151-1155 (1983)]; however, the nosology of this condition needs to be further elucidated, possibly on the basis of the underlying molecular genetic mechanisms of HSP and PMA.

Adult↗
PubMed1978

A clinical study of chronic childhood spinal muscular atrophy. A review of 141 cases.

The case histories and clinical details of 141 children (67 males and 74 females) with chronic childhood spinal muscular atrophy (SMA) have been reviewed. Hundred of these children were alive at the time of the study. The cases comprise a consecutive unselected series of all with this disease who presented to two large English neurological centres over a 10-year tracing period. Chronic childhood SMA is defined here as a progressive disease of anterior horn cells with initial proximal selectivity, which does not of itself cause death before 18 months of age. Clinical signs are first manifest between birth and 8 years of age, but in 95% before 3 years. Cumulative frequency tables for motor skills are presented; 46% of children never walked, even with orthopaedic aids; 37.6% were able to walk unaided at some stage. No child was able to run after 12 years of age. Late-presenting sporadic cases retain motor skills longer than do familial cases. A sex influence on the clinical course of the disease has been demonstrated, males being more severely affected. Cumulative frequency curves for age-at-onset and age-at-presentation have been compiled. A sib of an affected index case, still clinically normal at 2 years of age, has passed 90 percent of his risk period; the use of such cumulative frequency curves for studies of carrier-frequency and incidence is discussed. The median age at death for this disease exceeds 10 years. The range encompassed by the clinical spectrum is discussed.

Adolescent↗
PubMed2006

Modulating role of RNA structure in alternative splicing of a critical exon in the spinal muscular atrophy genes.

Humans have two nearly identical copies of the survival motor neuron (SMN ) gene, SMN1 and SMN2. Homozygous loss of SMN1 causes spinal muscular atrophy (SMA). SMN2 is unable to prevent the disease due to skipping of exon 7. Using a systematic approach of in vivo selection, we have previously demonstrated that a weak 5' splice site (ss) serves as the major cause of skipping of SMN2 exon 7. Here we show the inhibitory impact of RNA structure on the weak 5' ss of exon 7. We call this structure terminal stem-loop 2 (TSL2). Confirming the inhibitory nature of TSL2, point mutations that destabilize TSL2 promote exon 7 inclusion in SMN2, whereas strengthening of TSL2 promotes exon 7 skipping even in SMN1. We also demonstrate that TSL2 negatively affects the recruitment of U1snRNP at the 5' ss of exon 7. Using enzymatic structure probing, we confirm that the sequence at the junction of exon 7/intron 7 folds into TSL2 and show that mutations in TSL2 cause predicted structural changes in this region. Our findings reveal for the first time the critical role of RNA structure in regulation of alternative splicing of human SMN.

Alternative Splicing↗