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Spinal Muscular Atrophy (SMA) Carrier Tests
When a person has spinal muscular atrophy, then the portion of their nervous system that manages voluntary muscle movement is adversely affected. The nerve cells that control these muscle movements are located in the spine. Because the muscles cannot function normally, they begin to atrophy or become wasted.
Researchers Werdnig and Hoffman produced ground-breaking work on spinal muscular atrophy in the 1980s. They described a degenerative muscle disorder that often began in infancy and resulted in early death. Since then, more studies have occurred, and scientists classify spinal muscular atrophy, or SMA, in four groups based on the onset of symptoms.
Type I is the most severe form, with symptoms being evident at birth or shortly afterward. Children that manifest symptoms at between six and 12 months are categorized as having Type II. Type III tends to be a milder form that appears early in childhood or adolescence. Those who develop symptoms after the age of 30 are said to be affected by Type IV.
SMA is a result of a deficiency of a protein known as survival of motor neuron, or SMR. The protein’s main function is to ensure the efficiency of the body’s motor neurons. Genetic mutations on chromosome five have been identified as the cause of spinal muscular atrophy.
Symptoms of Spinal Muscular Atrophy
The earlier symptoms appear, the more severe they tend to be. Muscles that are closest to the center of the body, called the proximal muscles, are the most affected. This means that the upper back, shoulders, hips and thighs are frequently weakened. An infant with Type I is unable to support his head or sit up without assistance. Type II children may be able to sit on their own, but require assistance to attain a sitting position. Help for standing and walking is essential.
Children or adolescents with Type III may be able to stand and walk without help, but these tasks tend to become more difficult with age. Those with Type IV may experience only mild or moderate muscle weakness with increasing tendencies towards tremors and twitching. In any of the four types, it is possible for the muscles that control breathing and swallowing to become weakened, which can cause complications.
Life Expectancy with Spinal Muscular Atrophy
Not many years ago, doctors could only predict relatively low life expectancy for people with spinal muscular atrophy. Technological and treatment improvements have increased life expectancy, but it varies considerably based upon when onset occurs and the severity of the symptoms.
Spinal Muscular Atrophy Carriers
SMA is passed genetically from parents to children. Genes are inherited in pairs, with one-half of each pair coming from each parent. If a parent has one mutated gene, then they can be considered a carrier. As with other genetic disorders, carriers have no symptoms of spinal muscular atrophy. If two parents happen to be carriers of the mutated gene, then it is likely that their child will have SMA. Scientists estimate that where both parents are carriers, there is a 25 percent chance of having a child who is affected by the disorder.
Why Spinal Muscular Atrophy Genetic Carrier Testing Is Important
Anyone whose family has a history of SMA or who is related to known carriers should opt to be tested. Additionally, research suggests that one in 50 people may be a carrier, even if there is no family history of the disorder. A simple blood test is all that is required to determine if you are a carrier.
You can rely on DNAcarriertests.com to provide fast, accurate genetic carrier tests for SMA.