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Results for “Muscular Atrophy, Spinal”

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PubMed1989

Long-term ventilatory support in spinal muscular atrophy.

Before ethical issues regarding prolonging life in patients with degenerative disease can be considered, the quality of life with medical intervention must be delineated. We have followed 15 patients with spinal muscular atrophy who have been treated with mechanical ventilation. They have received assisted ventilation for an average of 8 years 10 months (range 5 months to 23 years 10 months). Three of the patients required full-time ventilator assistance at the time of initiation of ventilation; the remaining 12 used nighttime ventilation for an average of 8 years 7 months. Nine patients continue to receive nighttime ventilation only. Two patients died after 5 years and 14 years of assisted ventilation, respectively. Of the 10 patients more than 18 years of age, three graduated from college, two are in college, three graduated from high school, and two completed eleventh grade. One patient is a mother of a healthy child. Two patients are employed, and two others have found fulfilling volunteer work. Ventilator support has not significantly interfered with these patients' plans and expectations.

Adolescent↗

PubMed1997

Identification of proximal spinal muscular atrophy carriers and patients by analysis of SMNT and SMNC gene copy number.

The survival motor neuron (SMN) transcript is encoded by two genes, SMNT and SMNC. The autosomal recessive proximal spinal muscular atrophy that maps to 5q12 is caused by mutations in the SMNT gene. The SMNT gene can be distinguished from the SMNC gene by base-pair changes in exons 7 and 8. SMNT exon 7 is not detected in approximately 95% of SMA cases due to either deletion or sequence-conversion events. Small mutations in SMNT now have been identified in some of the remaining nondeletion patients. However, there is no reliable quantitative assay for SMNT, to distinguish SMA compound heterozygotes from non-5q SMA-like cases (phenocopies) and to accurately determine carrier status. We have developed a quantitative PCR assay for the determination of SMNT and SMNC gene-copy number. This report demonstrates how risk estimates for the diagnosis and detection of SMA carriers can be modified by the accurate determination of SMNT copy number.

Amino Acid Sequence↗

PubMed2001

Juvenile asymmetric segmental spinal muscular atrophy (Hirayama's disease): three cases without evidence of "flexion myelopathy".

Compression of the cervical spinal cord during neck movements ("flexion myelopathy") was proposed to be the main pathomechanism of juvenile asymmetric spinal muscular atrophy (JASSMA). We present 3 patients with the clinical appearance of JASSMA and typical high-intensity signals in the anterior horn cell region of the lower cervical spinal cord (T2-weighted magnetic resonance images) but without evidence of dynamic spinal cord compression. In all these patients pathomechanism distinct from mechanical damage must be assumed.

Adolescent↗

PubMed1999

Prenatal prediction of spinal muscular atrophy in Chinese.

We used linkage analysis, non-isotope SSCP (single-strand conformation polymorphism) and PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) for prenatal diagnosis of spinal muscular atrophy (SMA). A total of 26 cases from 20 SMA families (16, type 1 and 4) were evaluated. 5 out of 26 fetuses were affected and, following genetic counselling, the parents decided to terminate the pregnancies. Aborted fetal tissues were examined and the diagnosis was confirmed in each case. The 21 unaffected cases were either normals (12 cases) or carriers (9 cases). These children have been followed for six months to two and a half years. No false-negative or false-positive results on prenatal testing were found. We conclude that prenatal diagnosis of SMA is reliable and accurate.

Deoxyribonucleases, Type II Site-Specific↗

PubMedDate not supplied

Preservation of central motor conduction in patients with spinal muscular atrophy type II.

We evaluated the central (motor cortex to C8 motoneuron) and peripheral (C8 motoneuron to the muscle) motor conduction in 14 limbs of 7 patients with the intermediate form of spinal muscular atrophy (SMA II). The central motor conduction time (CMCT) was calculated using motor evoked potentials (MEPs) by transcranial magnetic stimulation and the results of a conventional F wave study. Peripheral conduction abnormality was found in 6 median nerves (43%) and 10 ulnar nerves (71%). Even in these patients with peripheral conduction abnormalities, the CMCT was consistently normal whenever the MEP was recorded. These results indicate that the motor conduction of the corticospinal fibers remains normal in SMA II.

Adolescent↗

PubMed2001

[A study of survival motor neuron and neuronal apoptosis inhibitory protein gene in spinal muscular atrophy].

OBJECTIVE: To study the absence of survival motor neuron(SMN) gene exon 7,8 and neuronal apoptosis inhibitory protein(NAIP) gene exon 5,6 in Chinese patients with type I - IV spinal muscular atrophy (SMA) and to confirm the relationship between the deletions of SMN, NAIP and SMA phenotype. METHODS: PCR and PCR-enzyme methods were used to detect the deletions of NAIP gene exon 5,6 and SMN gene exon 7,8 in 45 SMA (I - IV) patients and 30 healthy relatives of the patients and 30 normal controls. RESULTS: Deletions of exon 7 and 8 of the telomeric SMN gene were 4/4, 2/3, 1/8 and 0/30 in type I, II, III and IV SMA patients, respectively. One patient with type II lacked the exon 7 but retained exon 8. No deletions was found in the relatives and controls(0/60). No deletions of exon 5 and 6 of the NAIP gene was detected in all the patients, healthy relatives and controls. CONCLUSIONS: Deletions of SMN gene exon 7 and 8 exa mined by PCR-enzyme digestion could be recommended as an accurate gene diagnostic method for SMA with type I and II. However, the method was not as useful in type III as in I and II for making a diagnosis of SMA. Type IV SMA, a heterogeneous disease with phenotypical similarities to type I - III SMA, may be caused by deletion of other genes. The frequency of NAIP deletion was lower in Chinese SMA patients.

Child↗

PubMed1978

A clinical and genetic study of spinal muscular atrophy of adult onset: the autosomal recessive form as a discrete disease entity.

A clinical and genetic study of spinal muscular atrophy (SMA) of adult onset is reported. A genetic analysis of all cases of SMA occurring over a ten-year period in North-east England (48 index cases) has shown that chronic proximal SMA of adult onset is a distinct clinical and genetic entity, and is not a variant of the more common and relatively benign late juvenile cases. Nine cases of SMA of adult onset have been studied, occurring in 6 families. The median age of clinical onset was 35 years and the mean age at initial medical presentation was 37 years. The sex ratio was 5:4 (males:females). The condition is relatively benign and there is no evidence to date that life expectancy is shortened; there is usually no premonitory evidence of muscular weakness in early adult life. The muscular involvement is relatively symmetrical and the distal musculature is well preserved; clinical progression of the disease is interrupted by periods of apparent arrest. No patient was able to walk completely unaided twenty years after the initial clinical onset; the median age of patients in the study was 61 years but only one was confined to a wheelchair. In the early stages the recessive form of familial motor neuron disease must be excluded. A segregation analysis of sibs born after index cases was undertaken (segregation ratio of 0.20). This finding is consistent with autosomal recessive inheritance with an extended period during which the disease might initially present. The presence of new dominant mutations cannot be excluded, but is unlikely to account for more than 10% of cases. The carrier rate in the English population is estimated to be 1 in 300, with a gene frequency q = 0.00165. Prevalence is 0.32 per 100,000 in the general population. Empirical risks for genetic counselling are presented.

Adolescent↗

PubMed2006

Distal spinal muscular atrophy as a major feature in adult-onset ataxia telangiectasia.

The authors report four adult-onset ataxia telangiectasia (AT) patients belonging to two families lacking pronounced cerebellar ataxia but displaying distal spinal muscular atrophy. AT was proven by genetic studies showing ATM mutations and a reduced level of ATM. ATM activity, as measured by phosphorylation of p53, was close to normal, indicating that the p53 response is not the only factor in preventing neural damage in anterior horn cells in AT.

Adult↗

PubMed2005

A new mutation of IGHMBP2 gene in spinal muscular atrophy with respiratory distress type 1.

This report presents a new mutation in the first Japanese female infant with spinal muscular atrophy with respiratory distress type 1. She manifested the characteristic clinical features, including early-onset respiratory failure due to diaphragmatic paralysis and severe distal muscle weakness. Muscle biopsy in the femoral muscle indicated massive neurogenic changes. Sural nerve biopsy disclosed a moderate reduction of myelinated fibers, predominantly reduced large fibers. She had a novel homozygous missense mutation 2685 C -->A, leading to a T879K substitution in the immunoglobulin mu-binding protein 2 gene. Both parents were heterozygous for this mutation.

DNA-Binding Proteins↗

PubMed2004

Thalamic lesions in a long-surviving child with spinal muscular atrophy type I: MRI and EEG findings.

Brain magnetic resonance imaging was conducted in a girl with genetically confirmed spinal muscular atrophy (SMA) type I. This patient has survived 6 years, to date, under mechanical ventilation. T2-weighted and fluid-attenuated inversion recovery images revealed high signal intensity lesions in the anterolateral portions of the bilateral thalami. Electroencephalography disclosed diffuse beta activity upon awakening and during light sleep. In addition, fast and prolonged spindles were observed. Although mild neuronal changes in the lateral nucleus of the thalamus have been described in several autopsied cases, this is the first study to demonstrate neuroradiologically and neurophysiologically the thalamic lesions in genetically confirmed SMA type I.

Child↗

PubMed1996

Characterization of survival motor neuron (SMNT) gene deletions in asymptomatic carriers of spinal muscular atrophy.

Previous reports have established that the telomeric copy of the survival motor neuron (SMNT) gene and the intact copy of the neuronal apoptosis inhibitory protein (NAIP) gene are preferentially deleted in patients with spinal muscular atrophy (SMA). Although deletions or mutations in the SMNT gene are most highly correlated with SMA, it is not clear to what extent NAIP or other genes influence the SMA phenotype, or whether a small fraction of SMA patients actually have functional copies of both SMNT and NAIP. To evaluate further the part of SMNT in the development of SMA, we analyzed 280 asymptomatic SMA family members for the presence or absence of SMNT exons 7 and 8. We report the following observations: (i) 4% of the sample harbored a polymorphic variant of SMNT exon 7 that looks like a homozygous deletion; (ii) approximately 1% of the parents are homozygously deleted for both exons 7 and 8; (iii) one asymptomatic parent lacking both copies of SMNT exons 7 and 8 displays a 'subclinical phenotype' characterized by mild neurogenic pathology; (iv) another asymptomatic parent lacking both SMNT exons showed no signs of motor neuron disorder by clinical and neurodiagnostic analyses. The demonstration of polymorphic variants of exon 7 that masquerade as homozygous nulls, and the identification of SMA parents who harbor two disease alleles, serve as a caution to those conducting prenatal tests with these markers.

Adolescent↗

PubMed2005

Diverse small-molecule modulators of SMN expression found by high-throughput compound screening: early leads towards a therapeutic for spinal muscular atrophy.

We have exploited the existence of a second copy of the human SMN gene (SMN2) to develop a high-throughput screening strategy to identify potential small molecule therapeutics for the genetic disease spinal muscular atrophy (SMA), which is caused by the loss of the SMN1 gene. Our screening process was designed to identify synthetic compounds that increase the total amount of full-length SMN messenger RNA and protein arising from the SMN2 gene, thereby suppressing the deleterious effects of losing SMN1. A cell-based bioassay was generated that detects SMN2 promoter activity, on which greater than 550,000 compounds was tested. This resulted in the identification of 17 distinct compounds with confirmed biological activity on the cellular primary assay, belonging to nine different structural families. Six of the nine scaffolds were chosen on the basis of their drug-like features to be tested for their ability to modulate SMN gene expression in SMA patient-derived fibroblasts. Five of the six compound classes altered SMN mRNA levels or mRNA splicing patterns in SMA patient-derived fibroblasts. Two of the compound classes, a quinazoline compound series and an indole compound, also increased SMN protein levels and nuclear gem/Cajal body numbers in patient-derived cells. In addition, these two distinct scaffolds showed additive effects when used in combination, suggesting that they may act on different molecular targets. The work described here has provided the foundation for a successful medicinal chemistry effort to further advance these compounds as potential small molecule therapeutics for SMA.

Base Sequence↗

PubMed1991

[Neuropsychiatric approach to a child with spinal muscular atrophy. A study of relational problems].

Various years' experience of an extensive series of children suffering from progressive chronic spinal muscular atrophy have made it possible to elaborate a neuropsychiatric approach model conducted on the basis of a viewpoint capable of integrating the clinico-medical aspect and aptitude to empathic listening aimed at establishing a therapeutic alliance with the patient. With advancing age and the course of the disease, in most cases very different difficulties and problems are encountered. These change continuously in relation to the stage reached in emotional development. Entry to school and socialisation mark a particular moment in the confrontation with peers and present the ill child with his diversity. With the emergence of adolescent problems, there is also a dramatic new impact between the body image of a wounded, deteriorated self and the evolutionary effort aimed at identifying with the peer group, the autonomisation of parental figures, the integration of a sexed image of the self. Room can be found in this framework for the child neuropsychiatrist who is able to offer himself as a point of reference and set himself up as a model for elaborating disease anxieties. From personal experience it also emerges that in children suffering from a chronic, often fatal disease there is often the need for a physician to coordinate and integrate needs of both a clinical and sociorelational nature for the purpose of allowing the family to get closer to the needs of their child and prevent him from falling prey to destructive type anxieties.

Child↗

PubMed1996

An 11 base pair duplication in exon 6 of the SMN gene produces a type I spinal muscular atrophy (SMA) phenotype: further evidence for SMN as the primary SMA-determining gene.

The gene for autosomal recessive spinal muscular atrophy (SMA) has been mapped to 5q12 in a region that contains repeated markers and genes. Three cDNAs that detect deletions in SMA patients have been reported. One of these, the survival motor neuron (SMN) cDNA, is encoded by two genes (SMNT and SMNC) which are distinguished by base changes in exons 7 and 8. Exon 7 of the SMNT gene is not detectable in approximately 95% of SMA cases, due either to deletion or sequence conversion. There is limited information on the mutations in SMA patients that have detectable SMNT, these are critical for confirmation of SMNT as the SMA gene. Using SSCP analysis of the SMN exons we screened our SMA patients that possess at least one intact SMNT allele for mutations in SMNT. We identified one type I SMA patient with an 11 bp duplication in exon 6 which causes a frameshift and premature termination of the deduced SMNT protein. Dosage and SSCP analysis of SMNT in this family indicated that the father contributed a SMNT-deleted allele to the affected child whereas the mother passed on the 11 bp exon 6 duplication SMNT allele. Analysis of RNA by RT-PCR conclusively demonstrated that the 11 bp duplication is associated with the SMNT locus and not SMNC. This mutation provides strong support for SMN as the SMA-determining gene and indicates that disruption of SMNT on its own is sufficient to produce a severe type I SMA phenotype.

Alleles↗

PubMed2001

Correlation between genotype and phenotype in Korean patients with spinal muscular atrophy.

The goal of this study was to define the correlation between genotype and phenotype in Korean patients with spinal muscular atrophy (SMA). The SMA can be classified into three groups based on the age of onset and the clinical course. The candidate genes, survival motor neuron (SMN) gene, neuronal apoptosis inhibitory protein (NAIP) gene, and p44 gene were mapped and duplicated with telomeric and centromeric. The loss of the telomeric SMN occurs by a different mechanism. That is the deletion or conversion of telomeric SMN to centromeric SMN, in which case the conversion could produce a mild phenotype and deletion could produce a severe one. It has been known that there may be a balance between the numbers of copies expressed by the centromeric and telomeric SMN genes. In our study, ten patients with type I SMA and two type II patients were identified by their clinical findings and DNA studies. The major deletion of SMA candidate genes, deletion of the SMN gene, NAIP gene, and p44 gene were identified in six patients with type I SMA, while the rest of type I and all the type II patients showed the deletion of the SMN gene only. Allele numbers of the C212 marker were compared in patients and normal controls in order to find the correlation between the copy numbers and the clinical severity. The result was that type I patients had 2-5 alleles and the normal controls had 4-6. This suggests that the deletion is a major determining factor in the clinical phenotype. However, two type I patients with telomeric NAIP gene deletion notably had 4-5 alleles, as in the normal controls. This result implies that the correlation between the copy numbers and the severity is uncertain as opposed to the previous hypothesis. One type I patient showed the conversion of the centromeric SMN gene to the telomeric, which supports the conclusion that gene conversion is an important molecular mechanism for SMA. In the study of one hundred normal newborns, two physically normal newborns showed deletion of the centromeric SMN gene, suggesting frequent rearrangement in the locus.

Child↗

PubMed1990

Spinal muscular atrophy type I combined with atrial septal defect in three sibs.

All three children of an unrelated Norwegian couple were born with spinal muscular atrophy (SMA I) as confirmed by autopsy in two of them. Two of the children died at birth, whereas one lived for 7 weeks on support systems that included artificial ventilation. All three children had large atrial septal defects (ASD). One had valvular aortic stenosis. Another had arrhinencephaly and transient pleural effusion which was evacuated during pregnancy. The findings may reflect concurrence of unrelated disorders caused by genetic or environmental factors, segregation of linked genes, pleiotropism or the existence of a previously unknown disease.

Abnormalities, Multiple↗

PubMed1981

The pharyngo-laryngeal deficit in the acute form of infantile spinal muscular atrophy (Werdnig-Hoffmann disease).

The major complication in the acute form of infantile spinal muscular atrophy is the aspiration phenomenon, due to the pharyngo-laryngeal deficit. The radiographic findings of this deficit are characterized by epipharyngeal regurgitation, hypopharyngeal distention, good function of the cricopharyngeal sphincter and absence of epiglottic closure during the act of deglutition. The differential diagnosis of other neuromuscular entities is discussed in view of two documented radiographic cases.

Acute Disease↗

PubMed2002

Determinants of the interaction of the spinal muscular atrophy disease protein SMN with the dimethylarginine-modified box H/ACA small nucleolar ribonucleoprotein GAR1.

Deletion or mutation of the SMN1 (survival of motor neurons) gene causes the common, fatal neuromuscular disease spinal muscular atrophy. The SMN protein is important in small nuclear ribonucleoprotein (snRNP) assembly and interacts with snRNP proteins via arginine/glycine-rich domains. Recently, SMN was also found to interact with core protein components of the two major families of small nucleolar RNPs, fibrillarin and GAR1, suggesting that SMN may also function in the assembly of small nucleolar RNPs. Here we present results that indicate that the interaction of SMN with GAR1 is mediated by the Tudor domain of SMN. Single point mutations within the Tudor domain, including a spinal muscular atrophy patient mutation, impair the interaction of SMN with GAR1. Furthermore, we find that either of the two arginine/glycine-rich domains of GAR1 can provide for interaction with SMN, but removal of both results in loss of the interaction. Finally, we have found that unlike the interaction of SMN with the Sm snRNP proteins, interaction with GAR1 and fibrillarin is not enhanced by arginine dimethylation. Our results argue against post-translational arginine dimethylation as a general requirement for SMN recognition of proteins bearing arginine/glycine-rich domains.

Amino Acid Substitution↗