Spinal Muscular Atrophy: Clinical Classification and Disease Heterogeneity

Russman, Barry S.

doi:10.1177/0883073807305673

Cited by 225 publications

(188 citation statements)

References 44 publications

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“…Diagnosis is based on evidence, both electrophysiological and histological, of denervation of the muscle. 3 Nowadays, diagnosis is confirmed by molecular analysis to demonstrate an absent SMN1 gene exon 7. 2 Since this is a progressive neurodegenerative disease, patients with SMA require special care, which can halt disease progression and prolong their lives.…”

Section: Hoffmann Disease); 2) Intermediate (Type II or Chronicmentioning

confidence: 99%

“…Some patients classified as having type II SMA are able to sit up unaided while others can remain sitting if they are positioned, but cannot sit up unaided. 3 Better developed patients are able to remain standing if provided with support, but will nevertheless be unable to learn to walk.…”

Section: Classification Of Smamentioning

confidence: 99%

“…3 Children diagnosed with this form have very little control of their heads and cough and cry weakly.…”

Section: Classification Of Smamentioning

confidence: 99%

“…8 Life expectancy is around 10 to 40 years. 3,8 Type III SMA: (also known as juvenile SMA or KugelbergWelander syndrome) onset is after 18 months, but the actual age varies greatly. According to Wirth et al, 10 when the disease emerges before 3 years of age it is classified as Type IIIa SMA, whereas when onset is later, it is called Type IIIb SMA.…”

Section: Classification Of Smamentioning

confidence: 99%

“…The principal determinant of severity is the number of copies of SMN 2 , a gene that is similar to SMN 1 and is located in the centromeric region. 3 This genetic alteration to the SMN 1 gene is responsible for a reduction in survival motor neuron (SMN) protein. The SMN 2 gene does not completely compensate for the absence of SMN 1 expression because it only produces 25% of SMN protein.…”

Section: Introductionmentioning

confidence: 99%

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Atrofia muscular espinhal: diagnóstico, tratamento e perspectivas futuras

Baioni¹,

Ambiel²

2010

J. Pediatr. (Rio J.)

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Objective: To report on recent genetic and molecular discoveries and on future prospects for the treatment of spinal muscular atrophy (SMA), thereby helping healthcare professionals to make a quick diagnosis and provide appropriate and timely therapeutic support.Sources: Information was collected from scientific articles published in the last 2 decades, retrieved from the databases SciELO, PubMed, and MEDLINE. Summary of the findings:SMA is a neurodegenerative disorder with autosomal recessive genetic heredity. It is caused by a homozygous deletion of the survival motor neuron (SMN 1 ) gene. This genetic alteration results in reduced levels of the SMN protein, leading to degeneration of alpha motor neurons of the spinal cord and resulting in muscle weakness and progressive symmetrical proximal paralysis. It is known that basic nutritional and respiratory care and physiotherapy can be important to delaying disease progression and prolonging patients' lives. Several drugs are being tested, some new, others, such as valproic acid, already known; paralysis can be halted, but not reversed. Conclusions:SMA is a difficult to diagnose disorder, because it is little known, and treatment is uncertain. Pharmacological treatments and supportive therapies are not yet able to recover motor neurons or muscle cells that have already been lost, but are aimed at delaying disease progression and improving patients' residual muscle function, as well as offering better quality of life and life expectancy.

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Section: Hoffmann Disease); 2) Intermediate (Type II or Chronicmentioning

confidence: 99%

Section: Classification Of Smamentioning

confidence: 99%

“…3 Children diagnosed with this form have very little control of their heads and cough and cry weakly.…”

Section: Classification Of Smamentioning

confidence: 99%

Section: Classification Of Smamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Atrofia muscular espinhal: diagnóstico, tratamento e perspectivas futuras

Baioni¹,

Ambiel²

2010

J. Pediatr. (Rio J.)

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How Should Refusal of Tracheostomy as Part of an Adolescent's Perioperative Planned Intubation Be Regarded?

Gentry

Wightman

2018

AMA Journal of Ethics

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Spinal Muscular Atrophy

Farrar

Kiernan

2011

Encyclopedia of Life Sciences

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Spinal muscular atrophy (SMA) is a relatively common neurodegenerative disease marked by muscle weakness and atrophy due to degeneration of motor neurons of the spinal cord and lower brain stem. The most common form of SMA is caused by homozygous disruption of the survival motor neuron 1 ( SMN1 ) gene on chromosome 5q and results in insufficient levels of SMN protein in motor neurons. There is a broad spectrum of clinical severity, which inversely relates to the number of copies of the SMN2 gene. Although advances in the understanding of the disease biology have provided therapeutic targets, no effective disease modifying treatment is currently available. Promising therapeutic strategies include utilising the unique genomic structure of the SMN genes to increase SMN protein transcripts, neuroprotective agents, gene therapy and stem cell transplantation. Key Concepts: The most common form of SMA is secondary to homozygous disruption of the survival motor neuron 1 gene ( SMN1 ) located on chromosome 5q13 and results in insufficient levels of survival motor neuron (SMN) protein in motor neurons. SMA is classified into three common types based on age of onset and maximal motor milestones attained (Munsat and Davies, 1992): SMA type 1 has onset within the first 6 months and patients do not sit without support; SMA type 2 patients manifest weakness after 6 months of age and the maximum motor milestone is the ability to sit; SMA type 3 patients attain the ability to walk. The clinical spectrum of SMA is broad, ranging from early infant death to normal adult life with minimal weakness. The diagnosis of SMA is based on molecular genetic testing. Approximately 95% of individuals with SMA are homozygous for a deletion of SMN1 and 5% may reflect compound heterozygotes. In humans there is an almost identical copy of the gene, SMN2 , which predominantly encodes a truncated form of the SMN protein that is rapidly degraded. Functional ability inversely relates to SMN2 copy number. Current management incorporates multidisciplinary care and focuses on preventing and addressing the complications of weakness and promoting quality of life. Advances in the understanding of molecular pathogenesis of SMA have provided novel therapeutic targets, however translation has held limited success to date.

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Spinal Muscular Atrophy: Clinical Classification and Disease Heterogeneity

Cited by 225 publications

References 44 publications

Atrofia muscular espinhal: diagnóstico, tratamento e perspectivas futuras

Atrofia muscular espinhal: diagnóstico, tratamento e perspectivas futuras

How Should Refusal of Tracheostomy as Part of an Adolescent's Perioperative Planned Intubation Be Regarded?

Spinal Muscular Atrophy

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