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Spinal Muscular Atrophy (SMA) is a term applied to a number of different disorders, all having in common a genetic cause and the manifestation of weakness due to loss of the motor neurons of the spinal cord and brainstem. The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ...
The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ...
// G00-G99 - Diseases of the nervous system (G00-G09) Inflammatory diseases of the central nervous system (G00) Bacterial meningitis, not elsewhere classified (G01) Meningitis in bacterial diseases classified elsewhere (G02) Meningitis in other infectious and parasitic diseases classified elsewhere (G03) Meningitis due to other and unspecified causes (G04) Encephalitis, myelitis...
The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ...
The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ...
The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ...
The Disease Bold textDatabase is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ...
Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ...
This article or section does not adequately cite its references or sources. ...
â…”In vertebrates, the term motor neuron (or “motoneuronâ€) classically applies to neurons located in the central nervous system (CNS) which project their axons outside the CNS and directly or indirectly control muscles. ...
The Spinal cord nested in the vertebral column. ...
The brain stem is the stalk of the brain below the cerebral hemispheres. ...
Symptoms
Infantile SMA is the most severe form. Some of the symptoms include: In general, the earlier the symptoms appear, the shorter the life span. The onset is sudden and dramatic. Once symptoms appear the motor neuron cells quickly deteriorate shortly after. The disease can be fatal and there is no cure for SMA yet known. The major management issue in Type 1 SMA is the prevention and early treatment of respiratory infections; pneumonia is the cause of death in the majority of the cases. Infants with Type 1 SMA have a life expectancy of less than two years, however, some grow to be adults. Intellectual and later, sexual functions, are unaffected by SMA. Muscle weakness (or lack of strength) is a general term used during a diagnosis before the etiology can be identified. ...
Hypotonia is a serious medical condition that entails abnormally-decreased muscle tone, and is almost always found as early as infancy. ...
Suction is the creation of a partial vacuum, or region of low pressure. ...
Swallowing, known scientifically as deglutition, is the reflex in the human body that makes something pass from the mouth, to the pharynx, into the esophagus, with the shutting of the epiglottis. ...
Secretion is the process of segregating, elaborating, and releasing chemicals from a cell, or a secreted chemical substance or amount of substance. ...
Respiratory tract infections can refer to: Lower respiratory tract infection Upper respiratory tract infection Category: ...
Developmental milestones are tasks most children can perform at certain ages. ...
Diagnosis In order to be diagnosed with Spinal muscular atrophy, symptoms need to be present. In most cases a diagnosis can be made by the SMN gene test, which determines whether there is at least one copy of the SMN1 gene by looking for its unique sequences (that distinguish it from the almost identical SMN2) in exons 7 and 8. In some cases, when the SMN gene test is not possible or does not show any abnormality, other tests such as an EMG electromyography (EMG) or muscle biopsy may be indicated. Electromyography (EMG) is a medical technique for measuring muscle response to nervous stimulation. ...
Cause The region of chromosome 5 that contains the SMN (Survival Motor Neuron) gene has a large duplication. A large sequence that contains several genes occurs twice in adjacent segments. There are thus two copies of the gene, SMN1 and SMN2. The SMN2 gene has an additional mutation that makes it less efficient at making protein, though it does so in a low level. SMA is caused by loss of the SMN1 gene from both chromosomes. The severity of SMA, ranging from SMA 1 to SMA 3, is partly related to how well the remaining SMN 2 genes can make up for the loss of SMN 1. Often there are additional copies of SMN2, and an increasing number of SMN2 copies causes less severe disease. Chromosome 5 is one of the 23 pairs of chromosomes in humans. ...
Figure 1: A representation of a condensed eukaryotic chromosome, as seen during cell division. ...
All forms of SMN-associated SMA have a combined incidence of about 1 in 6,000. SMA is the most common cause of genetically determined neonatal death. The gene frequency is thus around 1:80, and approximately one in 40 persons are carriers. There are no known health consequences of being a carrier, and the only way one might know to consider the possibility is if a relative is affected.
Types
Caused by mutation of the SMN gene The most common form of SMA is caused by mutation of the SMN gene, and manifests over a wide range of severity affecting infants through adults. This spectrum has been divided arbitrarily into three groups by the level of weakness. - Infantile SMA - Type 1 or Werdnig-Hoffmann disease (generally 0-6 months). SMA type 1, also known as severe infantile SMA or Werdnig Hoffmann disease, is the most severe, and manifests in the first year of life with the inability to ever maintain an independent sitting position.
- Intermediate SMA - Type 2 (generally 7-18 months). Type 2 SMA, or intermediate SMA, describes those children who are never able to stand and walk, but who are able to maintain a sitting position at least some time in their life. The onset of weakness is usually recognized some time between 6 and 18 months.
- Juvenile SMA - Type 3 or Kugelberg-Welander disease (generally >18 months). SMA type 3 describes those who are able to walk at some time.
- Adult SMA - Type 4. Weakness usually begins in late adolesceence in tongue, hands, or feet then progresses to other areas of the body. Course of disease is much slower and has little or no impact on life expectancy.
Werdnig-Hoffman disease (or Infantile spinal muscular atrophy, type I) is an autosomal recessive muscular disease. ...
Kugelberg-Welander disease (or juvenile spinal muscular atrophy, type III) is an autosomal recessive muscular disease. ...
Statistic of forms SMA Statistic of forms (from Patient Registry Report, compiled by Connie Garland for the SMA Registry, The International Coordinating Committee for clinical trials in SMA ): - Affected Individuals: 1,535
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Other forms of SMA Other forms of spinal muscular atrophy are caused by mutation of other genes, some known and others not yet defined. All forms of SMA have in common weakness caused by denervation, that is, the muscle atrophies because it has lost the signal to contract due to loss of the innervating nerve. Spinal muscular atrophy only affects motor nerves. Heritable disorders that cause both weakness due to motor denervation along with sensory impairment due to sensory denervation are known by the inclusive label Charcot-Marie-Tooth or Hereditary Motor Sensory Neuropathy. The term spinal muscular atrophy thus refers to atrophy of muscles due to loss of motor neurons within the spinal cord. The foot of a person with Charcot_Marie_Tooth. ...
- Hereditary Bulbo-Spinal SMA Kennedy's disease (X linked, Androgen receptor)
- Spinal Muscular Atrophy with Respiratory Distress (SMARD 1) (chromsome 11, IGHMBP2 gene)
- Distal SMA with upper limb predominance (chromosome 7, glycyl tRNA synthase)
Kennedy disease (KD) or X-linked spinal-bulbar muscle atrophy is a neuromuscular disease associated with mutations of the androgen receptor (AR). ...
Chromosome 7 is one of the 23 pairs of chromosomes in humans. ...
Treatment The course of SMA is directly related to the severity of weakness. Infants with the severe form of SMA frequently succumb to respiratory disease due to weakness of the muscles that support breathing. Children with milder forms of SMA naturally live much longer although they may need extensive medical support, especially those at the more severe end of the spectrum.
Although gene replacement strategies are being tested in animals, current treatment for SMA consists of prevention and management of the secondary effect of chronic motor unit loss. It is likely that gene replacement for SMA will require many more years of investigation before it can be applied to humans. Due to molecular biology, there is a better understanding of SMA. The disease is caused by deficiency of SMN (survival motor neuron) protein, and therefore approaches to developing treatment include searching for drugs that increase SMN levels, enhance residual SMN function, or compensate for its loss. Molecular biology is the study of biology at a molecular level. ...
Much can be done for SMA patients in terms of medical and in particular respiratory, nutritional and rehabilitation care. However, there is currently no drug known to alter the course of SMA. Significant progress has been made in preclincial research towards an effective treatment. Several drugs have been identified in laboratory experiments that hold promise for patients. To evaluate if these drugs benefit SMA patients, clinical trials are needed. In a clinical trial a new medication is tested while the patients are carefully monitored for their safety and for any possible drug effects, positive or negative.
Some drugs under clinical investigation for the treatment of SMA:
Butyrate, an ester or salt of butyric acid, can refer to: Methyl butyrate Ethyl butyrate Categories: | ...
Valproic acid is a chemical compound that has found clinical use as an anticonvulsant and mood-stabilizing drug, primarily in the treatment of epilepsy and bipolar disorder. ...
Research In 1978 Pearn Corporation published a series of papers on SMA. They reported that childhood onset SMA is not an uncommon disease and has an incidence in the range of 4 per 100,000, which makes it at least twice as common as Amyotrophic Lateral Sclerosis (ALS, also known as Lou Gehrig's disease). They confirmed it is an autosomal recessive inheritance gene and defined the later-onset type as a more benign autosomal dominant gene. Spinal muscular atrophy is the second most common lethal, autosomal recessive disease in Caucasians. Amyotrophic lateral sclerosis (ALS, sometimes called Lou Gehrigs disease, Maladie de Charcot or motor neurone disease) is a progressive, fatal neurodegenerative disease caused by the degeneration of motor neurons. ...
In genetics, the term recessive gene refers to an allele that causes a phenotype (visible or detectable characteristic) that is only seen in a homozygous genotype (an organism that has two copies of the same allele). ...
It has been suggested that this article or section be merged into Dominance relationship. ...
This article does not cite its references or sources. ...
For SMA 1 it takes a recessive gene from both parents in order to have the disease, if both parents have the recessive gene, each baby has a 25% chance of having the illness. Each of their subsequent children have a 50% of carrying the recessive gene. Couples may want to have genetic counseling before deciding to have more children. Counseling is available to these families through the community. In 1990 mapping of the gene for SMA to chromosome 5q11.2-13.3 was reported and culminated in a 3 year research funded in part by the Muscular Dystrophy Association. The findings were also confirmed by French researchers. The identification of the gene for autosomal recessive SMA on chromosome 5q has allowed for prenatal diagnosis. Families who are at risk, or who have had a child with the diagnosis can have an amniocentesis done during pregnancy for DNA testing. Chromosome 5 is one of the 23 pairs of chromosomes in humans. ...
Muscular Dystrophy Association (MDA) is a U.S. organization founded in 1950 which combats muscular dystrophy and diseases of the nervous system and muscular system in general by funding research, providing medical and community services, and educating health professionals and the general public. ...
Amniocentesis, or an Amniotic Fluid Test (AFT), is a medical procedure used for prenatal diagnosis, in which a small amount of amniotic fluid is extracted from the amnion around a developing fetus. ...
Adults with SMA Although SMA often results in death during childhood, some people with SMA survive into adulthood and even old age. Actual lifespan depends greatly on the severity of SMA in each individual, and the three major types of SMA provide only a rough diagnostic guide; however even some individuals diagnosed with type-1 SMA survive to adulthood. Intellectual ability is unaffected by SMA, and adults with SMA benefit greatly from the use of assistive technology, such as speech recognition or Switch Access software. Such devices allow people with even very limited mobility to use a computer to read, write, communicate, play video games, and access environmental controls. Sexual response and reproductive functions are also unaffected by SMA; individuals with SMA can enjoy active sex lives and have given birth to children. Assistive Technology (AT) is a generic term that includes assistive, adaptive, and rehabilitative devices and the process used in selecting, locating, and using them. ...
Speech recognition (in many contexts also known as automatic speech recognition, computer speech recognition or erroneously as Voice Recognition) is the process of converting a speech signal to a sequence of words, by means of an algorithm implemented as a computer program. ...
Many people with severe physical or cognitive impairment use one or more switches to access computers. ...
One example of an adult living with SMA-I is Ami Ankilewitz, who was 34 years old as of 2005, outliving his predicted life expectancy by 28 years. His experiences are presented in the documentary 39 Pounds of Love, whose title refers to his total body weight. 2005 is a common year starting on Saturday of the Gregorian calendar. ...
Documentary film is a broad category of visual expression that is based on the attempt, in one fashion or another, to document reality. ...
The 'Baby MB' Case On March 15th 2006, the court ruled that 17 month old "Baby MB" (identity withheld) was to be kept alive, contrary to 14 medical professional's advice - one of the medics 'Dr. S' stating "I think that the cumulative effect of the condition's effects is that he has an intolerable life" [1]. The judge said that "he felt the child gained enough pleasure from life to outweigh the medical evidence of his condition" [2].
Specialists' reactions: [3]
References
See also Polyneuropathy in dogs and cats is a collection of peripheral nerve disorders that often are breed-related in these animals. ...
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