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Spinal Muscular Atrophy (SMA)

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Spinal muscular atrophy (SMA) is a genetic disorder that affects the part of the nervous system that controls voluntary muscle movement. SMA is an autosomal recessive disease where each parent usually carries the mutated gene and both mutated genes are inherited to acquire the disease. “Two carriers have a twenty-five percent chance of having an unaffected child with two normal genes, a fifty percent chance of having an unaffected child who also is a carrier, and a twenty-five percent chance of having an affected child with two recessive genes (“Autosomal Recessive”).” Not many people are aware of SMA but,1 in 50 people are carriers of SMA and about 1 in 10,000 babies are affected (“Cure SMA”). People can get DNA testing done to see if they…show more content…
The SMN1 gene is responsible for the creation of the SMN protein, and without this protein, the motor neurons of the spinal cord and brainstem die off and muscles weaken and waste (atrophy). Muscles used for swallowing, crawling, walking, sitting up and controlling head movement are mainly affected. If one copy of the defected gene and one regular copy of the gene are inherited, than the child will be a carrier of the disease and will not have any symptoms. There are four types of SMA, Type I, Type II, Type II, and Type IV. Each type has different symptoms, age of onset, and severity but, each type affects each person differently.
Type I SMA which is also called Werdnig-Hoffmann Disease or Infantile Onset, is detected before six months of age and is the most common and most severe form of SMA. Children with this type are usually very developmentally delayed and have problems swallowing, breathing, and holding their heads up. “Swallowing and feeding will become difficult for children with this type of SMA and they will eventually lose the ability to swallow safely without aspirating (choking or inhaling secretions and food particles into the lungs)(Battista 5).” The life expectancy for infants with Type I is less than two
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Children with this type can sit up on their own, but will need assistance getting there. They will never be able to walk or stand on their own. The progression of symptoms can vary greatly with Type II. and because of this, many patients can either live into adulthood and live a normal life or die in an early childhood due to respiratory failure. About seventy percent of patients with Type II are alive at age twenty-five ( The muscles will gradually weaken over time, the thighs before the feet and the legs before the arms. Their hands may weaken but patients will still be able to type and do other basic functions (Ferro 4). The biggest threat with Type II is scoliosis which is a curvature of the spine. Scoliosis can cause an interference in mobility and can cause a change in shape to the chest cavity (Spiegel). “Many physicians believe that severe spinal curvatures also compromise respiratory function, since the curved spine often compresses a lung. In severe SMA, it’s hard to say how much respiratory decline would have occurred even without the curvature, so its contribution is uncertain. (Ferro).” Spine straightening surgery is usually recommended but is risky due to the use of anesthesia and the possible dangerous outcomes such as, postanesthetic respiratory
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