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PubMed1979

Blood selenium in chronic spinal muscular atrophy.

The spinal muscular atrophies (SMA) of childhood comprise the second most common fatal recessive disease after cystic fibrosis, yet the nature of the biochemical defect causing the anterior horn cell degeneration is totally unknown. Recent reports of a cluster of adult motor neurone disease cases from a high seleniferous area in South Dakota have prompted the study of blood selenium in children with SMA in Australia. Eight children with chronic SMA were tested, in addition to 9 obligate heterozygote carriers of the gene. Blood selenium levels of patients and carriers did not differ significantly from that observed in controls. The mammalian effects of selenium toxicity are discussed.

Adolescent↗
PubMed2003

A transgene carrying an A2G missense mutation in the SMN gene modulates phenotypic severity in mice with severe (type I) spinal muscular atrophy.

5q spinal muscular atrophy (SMA) is a common autosomal recessive disorder in humans and the leading genetic cause of infantile death. Patients lack a functional survival of motor neurons (SMN1) gene, but carry one or more copies of the highly homologous SMN2 gene. A homozygous knockout of the single murine Smn gene is embryonic lethal. Here we report that in the absence of the SMN2 gene, a mutant SMN A2G transgene is unable to rescue the embryonic lethality. In its presence, the A2G transgene delays the onset of motor neuron loss, resulting in mice with mild SMA. We suggest that only in the presence of low levels of full-length SMN is the A2G transgene able to form partially functional higher order SMN complexes essential for its functions. Mild SMA mice exhibit motor neuron degeneration, muscle atrophy, and abnormal EMGs. Animals homozygous for the mutant transgene are less severely affected than heterozygotes. This demonstrates the importance of SMN levels in SMA even if the protein is expressed from a mutant allele. Our mild SMA mice will be useful in (a) determining the effect of missense mutations in vivo and in motor neurons and (b) testing potential therapies in SMA.

Animals↗
PubMed2001

Spinal muscular atrophy.

The spinal muscular atrophies are a group of mostly inherited disorders selectively affecting the lower motor neuron. There is a wide degree of clinical and genetic heterogeneity that must be taken into account when giving prognostic information. Autosomal recessive childhood proximal SMA is the commonest form and is due to mutations in a gene encoding a novel protein, SMN, that appears to play a critical role in RNA metabolism but has also been shown to interact with actin-binding proteins and mediators of programmed cell death. The identification of the genetic basis of SMA has resulted in advances for prenatal diagnosis and in new insights into motor neuron biology. The chromosomal location of two of the rarer dominant forms of SMA has been found. Identification of the molecular pathophysiology of lower motor neuron syndromes can be expected to aid in the development of therapy for these disabling disorders.

Adult↗
PubMed1998

The role of the SMN gene in proximal spinal muscular atrophy.

Childhood spinal muscular atrophy (SMA) is a common recessive autosomal disorder that results in degeneration of lower motor neurons. The identification of the disease gene, Survival of Motor Neuron (SMN), was a major advance in understanding the molecular basis underlying this devastating neuromuscular disease. This finding has greatly improved the genetic counselling of SMA families. Recently, biochemical studies demonstrated its involvement in the biogenesis of spliceosomal snRNPs, suggesting a critical role of SMN in RNA processing. Surprisingly, other studies showed a putative role of SMN in an anti-apoptotic pathway involving Bcl-2. The function of SMN protein is not fully understood. These observations emphasized the difficulty in elucidating the function of any novel protein. Therefore, multidisciplinary approaches are required to understand the pathogenesis of SMA.

Animals↗
PubMed2000

Animal models of spinal muscular atrophy.

Proximal spinal muscular atrophy (SMA) is the second most common autosomal recessive inherited disorder in humans. It is the most common genetic cause of infant mortality. As yet, there is no cure for this neuromuscular disorder which affects the lower motor neurons and proximal muscles of the limbs and trunk. In the last decade, significant advances have been made in understanding this disease, from linkage analysis to isolating the defective gene and identifying its protein product. This review summarizes the most recent advance in SMA research: the development of animal models of the disease, in particular mouse models of SMA. The SMA mice that we describe here present with symptoms similar to those seen in SMA patients. They promise to further the understanding of the molecular basis of this disease and demonstrate the feasibility of using the intact SMN2 gene, found in all SMA patients, as a means of treating this disorder.

Animals↗
PubMed1995

A novel cDNA detects homozygous microdeletions in greater than 50% of type I spinal muscular atrophy patients.

Spinal muscular atrophy (SMA) is the second most common lethal, autosomal recessive disease in Caucasians (after cystic fibrosis). Childhood SMAs are divided into three groups (type I, II and III), which are allelic variants of the same locus in a region of approximately 850 kb in chromosome 5q12-q13, containing multiple copies of a novel, chromosome 5-specific repeat as well as many atypical pseudogenes. This has hampered the identification of candidate genes. We have identified several coding sequences unique to the SMA region. A genomic fragment detected by one cDNA is homozygously deleted in 17/29 (58%) of type I SMA patients. Of 235 unaffected individuals examined, only two showed the deletion and both are carriers of SMA. Our results suggest that deletion of at least part of this novel gene is directly related to the phenotype of SMA.

Base Sequence↗
PubMed1995

A frame-shift deletion in the survival motor neuron gene in Spanish spinal muscular atrophy patients.

Spinal muscular atrophy (SMA) is a frequent autosomal recessive disease characterized by degeneration of the motor neurons of the spinal cord causing proximal paralysis with muscle atrophy. The region on chromosome 5q13 encompassing the disease gene is particularly unstable and prone to large-scale deletions whose characterization recently led to the identification of the survival motor neuron (SMN) gene. We now present a genetic analysis of 54 unrelated Spanish SMA families that has revealed a 4-basepair (bp) deletion (AGAG) in exon 3 of SMN in four unrelated patients. This deletion, which results in a frameshift and a premature stop codon, occurs on the same haplotype background, suggesting that a single mutational event is involved in the four families. The other patients showed either deletions of the SMN gene (49/54) or a gene conversion event changing SMN exon 7 into its highly homologous copy (cBCD541, 1/54). This observation gives strong support to the view that mutations of the SMN gene are responsible for the SMA phenotype as it is the first frameshift mutation reported in SMA.

Base Sequence↗
PubMed2007

Stat5 constitutive activation rescues defects in spinal muscular atrophy.

Proximal spinal muscular atrophy (SMA) is a motor neuron degeneration disorder for which there is currently no effective treatment. Here, we report three compounds (sodium vanadate, trichostatin A and aclarubicin) that effectively enhance SMN2 expression by inducing Stat5 activation in SMA-like mouse embryonic fibroblasts and human SMN2-transfected NSC34 cells. We found that Stat5 activation enhanced SMN2 promoter activity with increase in both full-length and deletion exon 7 SMN transcripts in SMN2-NSC34 cells. Knockdown of Stat5 expression disrupted the effects of sodium vanadate on SMN2 activation but did not influence SMN2 splicing, suggesting that Stat5 signaling is involved in SMN2 transcriptional regulation. In addition, constitutive activation of Stat5 mutant (Stat5A1*6) profoundly increased the number of nuclear gems in SMA-patient lymphocytes and reduced SMA-like motor neuron axon outgrowth defects. These results demonstrate that Stat5 signaling could be a possible pharmacological target for treating SMA.

Aclarubicin↗
PubMed1994

Linkage mapping of the spinal muscular atrophy gene.

Spinal muscular atrophy (SMA) is a common autosomal recessive disorder resulting in loss of motor neurons. We have performed linkage analysis on a panel of families using nine markers that are closely linked to the SMA gene. The highest lod score was obtained with the marker D5S351 (Zmax = 10.04 at theta = O excluding two unlinked families, and Zmax = 8.77 at theta = 0.007 with all families). One type III family did not show linkage to the 5q13 markers, and in one type I consanguineous family the affected individual did not show homozygosity except for the marker D5S435. Three recombinants were identified with the closet centromeric marker, D5S435, which position the gene telomeric of this marker. These recombinants will facilitate finer mapping of the location of the SMA gene. Lastly, two families provide strong evidence for a remarkable variability in presentation of the SMA phenotype, with the age at onset in one family varying from 17 months to 13 years.

Adolescent↗
PubMed1998

Maternal mosaicism for a second mutational event in a type I spinal muscular atrophy family.

Spinal muscular atrophy (SMA) is a common fatal motor-neuron disorder characterized by degeneration of the anterior horn cells of the spinal cord, which results in proximal muscle weakness. Three forms of the disease, exhibiting differing phenotypic severity, map to chromosome 5q13 in a region of unusually high genomic variability. The SMA-determining gene (SMN) is deleted or rearranged in patients with SMA of all levels of severity. A high de novo mutation rate has been estimated for SMA, based on the deletion of multicopy microsatellite markers. We present a type I SMA family in which a mutant SMA chromosome has undergone a second mutation event. Both the occurrence of three affected siblings harboring this same mutation in one generation of this family and the obligate-carrier status of their mother indicate the existence of maternal germ-line mosaicism for cells carrying the second mutation. The existence of secondary mutational events and of germ-line mosaicism has implications for the counseling of SMA families undergoing prenatal genetic analysis.

Alleles↗
PubMed1995

The gene for neuronal apoptosis inhibitory protein is partially deleted in individuals with spinal muscular atrophy.

The spinal muscular atrophies (SMAs), characterized by spinal cord motor neuron depletion, are among the most common autosomal recessive disorders. One model of SMA pathogenesis invokes an inappropriate persistence of normally occurring motor neuron apoptosis. Consistent with this hypothesis, the novel gene for neuronal apoptosis inhibitory protein (NAIP) has been mapped to the SMA region of chromosome 5q13.1 and is homologous with baculoviral apoptosis inhibitor proteins. The two first coding exons of this gene are deleted in approximately 67% of type I SMA chromosomes compared with 2% of non-SMA chromosomes. Furthermore, RT-PCR analysis reveals internally deleted and mutated forms of the NAIP transcript in type I SMA individuals and not in unaffected individuals. These findings suggest that mutations in the NAIP locus may lead to a failure of a normally occurring inhibition of motor neuron apoptosis resulting in or contributing to the SMA phenotype.

Amino Acid Sequence↗
PubMed2006

[Eosinophil-derived neurotoxin as a new additional clinical marker in spinal muscular atrophies].

INTRODUCTION: Spinal muscular atrophies (SMA) are group of neuromuscular disorders characterized by degeneration of motorneurons in anterior column of medulla spinalis, and sometimes in motoneurons of cranial nerves and the brain. Causes of SMAs are mutations in genes encoding for SMN, SIP and NAIP that are very low in motorneurons of these patients. Ribonucleases (RNases) are enzymes that depolimerize RNA and may destabilize DNA. AIM: The objective of this study was to determine ribonuclease activity in serum and urine of SMA patients. METHODS: RNases were purified by anion-kation-exchange chromatographies, and HPLC, and their activity was measured by immunodetection using specific antibodies against rinonucleases in presence of RNA as a substrate. RESULTS: Eosinophil-derived neurotoxin (EDN) activity iin serum of SMA patients was 5.6, 3.8 and 2.6 higher in type I, II and III comparing with control group. RNase inhibitor activity in serum of the same patients was 3.0 and 2.4 lower in type I and II vs. Control group, but in type III was unchanged. Similar results are found in urine of the same patients. CONCLUSION: Increased serum and urin EDN activities in SMA patients could be used as a new additional clinical marker in their diagnosis.

Biomarkers↗
PubMed2003

Difficult airway in a child with spinal muscular atrophy type I.

Spinal muscular atrophy (SMA) type I is a relatively common inherited neuromuscular disease of hypotonic newborns, but is not associated with craniofacial abnormalities. There is nothing in the literature about difficult intubation in patients affected by this disease. We report a case of 34-month-old girl with SMA type I who was scheduled for emergency endoscopic laser treatment of tracheal stenosis caused by granulations. Tracheostomy was performed at 17 months of age and before this, the orotracheal tube was changed periodically without difficulty. For this laser treatment, orotracheal intubation was required. Preoperative physical examination revealed micrognathia and class II malocclusion. Opening her mouth was not difficult. Although difficult orotracheal intubation was predictable, we attempted to intubate her trachea as usual, but could not visualize the epiglottis. We decided to proceed with retrograde intubation, one of the standard techniques employed in a child with a difficult airway, via the tracheostome. A feeding nasogastric catheter was used as a guide catheter, and our strategy was successful. In this study we report a case of difficult airway in a child with SMA type I. The relationship between SMA type I with a tracheostome and difficult airway are discussed.

Airway Obstruction↗
PubMed2001

Coilin forms the bridge between Cajal bodies and SMN, the spinal muscular atrophy protein.

Spinal muscular atrophy (SMA) is a genetic disorder caused by mutations in the human survival of motor neuron 1 gene, SMN1. SMN protein is part of a large complex that is required for biogenesis of various small nuclear ribonucleoproteins (snRNPs). Here, we report that SMN interacts directly with the Cajal body signature protein, coilin, and that this interaction mediates recruitment of the SMN complex to Cajal bodies. Mutation or deletion of specific RG dipeptide residues within coilin inhibits the interaction both in vivo and in vitro. Interestingly, GST-pulldown experiments show that coilin also binds directly to SmB'. Competition studies show that coilin competes with SmB' for binding sites on SMN. Ectopic expression of SMN and coilin constructs in mouse embryonic fibroblasts lacking endogenous coilin confirms that recruitment of SMN and splicing snRNPs to Cajal bodies depends on the coilin C-terminal RG motif. A cardinal feature of SMA patient cells is a defect in the targeting of SMN to nuclear foci; our results uncover a role for coilin in this process.

Amino Acid Sequence↗
PubMed2006

Fine-mapping and candidate gene analysis of bovine spinal muscular atrophy.

Bovine spinal muscular atrophy (SMA), an autosomal recessive neurodegenerative disease, has been mapped at moderate resolution to the distal part of Chromosome 24. In this article we confirm this location and fine-map the SMA locus to an interval of approximately 0.8 cM at the very distal end of BTA24. Despite remarkable similarity to human SMA, the causative gene SMN can be excluded in bovine SMA. However, the interval where the disease now has been mapped contains BCL2, like SMN an antiapoptotic factor, and shown to bind to SMN. Moreover, knockout mice lacking the BCL2 gene show rapid motor neuron degeneration with early postnatal onset, as observed in bovine SMA. A comparative cattle/human map of the distal end of BTA24, based on the emerging bovine genome sequencing data, shows conserved synteny to HSA18 with hints of a segmental duplication and pericentric inversion just after the last available bovine marker DIK4971. This synteny lets us conclude that SMA is in immediate vicinity of the telomere. Candidate gene analysis of BCL2, however, excludes most of this gene, except its promoter region, and draws attention to the neighboring gene VPS4B, part of the endosomal protein-sorting machinery ESCRT-III which is involved in several neurodegenerative diseases.

Animals↗
PubMed2003

Development of a gene therapy strategy for the restoration of survival motor neuron protein expression: implications for spinal muscular atrophy therapy.

Spinal muscular atrophy (SMA) is a motor neuron degeneration disorder, and manifests itself in patients as muscle weakness and paralysis that ultimately leads to death. Currently, there is no effective treatment for this disease. As a first step in developing a treatment for SMA, we are examining whether delivery of the gene encoding survival motor neuron (SMN) protein to primary fibroblast cell lines derived from SMA patients can lead to restoration of nuclear-staining foci, called gems, which are absent in patients with severe SMA. Using adenovirus-mediated gene delivery, we show that SMN can be efficiently expressed in patient fibroblasts, and leads to restoration of nuclear gems, which are thought to be important for the functional rescue of the SMA phenotype. The number of gems per cell is equal to or greater than those found in fibroblasts of normal individuals. Furthermore, ectopic expression of SMN also caused relocalization of Gemin2, an SMN-interacting protein, to gems. Overall, this work is the first demonstration of the feasibility of virus-based delivery of the SMN-coding gene to restore the normal SMN expression pattern in SMA patient-derived cells, and holds promise for gene therapy of SMA, as a potential long-term therapy for this devastating childhood disease.

Adenoviridae↗
PubMed1994

A multicopy dinucleotide marker that maps close to the spinal muscular atrophy gene.

Spinal muscular atrophy (SMA) is a common autosomal recessive disorder resulting in loss of motor neurons. The interval containing the SMA gene has been defined by linkage analysis as 5qcen-D5S435-SMA-D5S557-5qter. We have isolated a new dinucleotide repeat marker, CATT1, that lies between these two closest markers. The marker CATT1 has 16 alleles and is highly polymorphic. The marker can have 1 to 4 (or more) copies per chromosome, giving rise to individuals with up to 8 (or more) alleles. All of the subloci map between the markers D5S557 and D5S435 and lie in close proximity to one another. The marker CATT1 is linked to the SMA gene with a lod score of Zmax = 34.42 at theta = 0 and crosses all available recombinants. Certain alleles occurred more frequently in either the SMA or normal populations, indicating significant allelic association between CATT1 and the SMA locus. Haplotype analysis combining U.S. and Canadian SMA families reveals that one haplotype group (VII) occurs significantly more frequently in the SMA population than in the normal. This confirms the allelic association of CATT1 with the SMA locus.

Alleles↗
PubMed1997

Missense mutations in exon 6 of the survival motor neuron gene in patients with spinal muscular atrophy (SMA).

Spinal muscular atrophy (SMA) is a frequent autosomal recessive neurodegenerative disorder leading to weakness and atrophy of voluntary muscles. The survival motor neuron gene (SMN) is a strong candidate for SMA and present in two highly homologous copies (telSMN and cenSMN) within the SMA region (5q11.2-q13.3). More than 90% of SMA patients show homozygous deletions of at least exon 7 of telSMN, whereas absence of cenSMN seems to have no clinical consequences. In 23 non-deleted SMA patients, we searched for intragenic mutations of the SMN genes in exons 1-7 and the promotor region by single strand conformation analysis. We identified two different missense mutations, S2621 and T2741, in exon 6 of telSMN in three independent SMA families, providing further evidence for the telSMN gene as a SMA determining gene. Both mutations, as well as two previously described mutations (Y272C and G279V) are located within a highly conserved interval from codon 258 to codon 279 which seems to be an important functional domain of the telSMN protein. Recently, this region has been shown to contain a tyrosine/glycine-rich motif, which is also present in various RNA binding proteins, suggesting a potential role of SMN in RNA metabolism. Missense mutations might be useful for in vivo and transgenic experiments and further investigations on understanding the function of the telSMN protein.

Adolescent↗