Anyone know anything about spinal muscular atrophy?
Answers:
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.
Infantile SMA is the most severe form. Some of the symptoms include:
muscle weakness
poor muscle tone
weak cry
limpness or a tendency to flop
difficulty sucking or swallowing
accumulation of secretions in the lungs or throat
the legs tend to be weaker than the arms
feeding difficulties
increased susceptibility to respiratory tract infections
developmental milestones, such as lifting the head or sitting up, can't be reached.
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.
[edit] 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.
[edit] 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.
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.
[edit] Types
[edit] 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 four 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.
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.
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.
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:
Butyrates
Valproic acid
Hydroxyurea
Riluzole
A coworker of mine has a two year old daughter who has it. I don't know much but there's lots of info out there. Here's one good site.
http://www.fsma.org/
Weak muscles supporting one side or area of the spine. Probably could be corrected with proper bracing or physical therapy. See a good chiropractor for help.
Spinal Muscular Atrophy (SMA) is a motor neuron disease. The motor neurons affect the voluntary muscles that are used for activities such as crawling, walking, head and neck control, and swallowing. It is a relatively common "rare disorder": approximately 1 in 6000 babies born are affected, and about 1 in 40 people are genetic carriers.
SMA affects muscles throughout the body, although the proximal muscles (those closest to the trunk of one�s body - i.e. shoulders, hips, and back) are often most severely affected. Weakness in the legs is generally greater than in the arms. Sometimes feeding and swallowing can be affected. Involvement of respiratory muscles (muscles involved in breathing and coughing) can lead to an increased tendency for pneumonia and other lung problems. Sensation and the ability to feel are not affected. Intellectual activity is normal and it is often observed that patients with SMA are unusually bright and sociable. Patients are generally grouped into one of four categories, based on certain key motor function milestones.
SMA is an autosomal recessive genetic disease. In order for a child to be affected by SMA, both parents must be carriers of the abnormal gene and both must pass this gene on to their child. Although both parents are carriers the likelihood of a child inheriting the disorder is 25%, or 1 in 4.
An individual with SMA has a missing or mutated gene (SMN1, or survival motor neuron 1) that produces a protein in the body called Survival Motor Neuron (SMN) protein. This protein deficiency has its most severe affect on motor neurons. Motor neurons are nerve cells in the spinal cord which send out nerve fibers to muscles throughout the body. Since SMN protein is critical to the survival and health of motor neurons, without this protein nerve cells may atrophy, shrink and eventually die, resulting in muscle weakness.
As a child with SMA grows their bodies are doubly stressed, first by the decrease in motor neurons and then by the increased demands on the nerve and muscle cells as their bodies grow larger. The resulting muscle atrophy can cause weakness and bone and spinal deformities that may lead to further loss of function, as well as additional compromise of the respiratory (breathing) system.
There are four types of SMA, SMA Type I, II, III, IV. The determination of the type of SMA is based upon the physical milestones achieved. It is important to note that the course of the disease may be different for each child.
SMA is diagnosed primarily through a blood test, which looks for the presence or absence of the SMN1 gene, in conjunction with a suggestive history and physical examination.
Some drugs under clinical investigation for the treatment of SMA:
* Butyrates
* Valproic acid
* Hydroxyurea
* Riluzole
The information post by website user , Helpde.com not guarantee correctness.