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Spinal Muscular Atrophy
Spinal Muscular Atrophy (SMA) is a hereditary disorder and it is an autosomal recessive disorder. The age of onset and severity of SMA varies. Type I, from an infantile causes early death from respiratory failure. Type II, from a juvenile onset causes individuals to have a reduced life expectancy and are unable to walk.
Spinal muscular atrophy is inherited as an autosomal recessive trait and has an incidence of approximately 4 per 100,000 people. For diagnosis, tests or operations such as muscle biopsy or electromyography can be administered to find out if you have it. Some of the symptons in babies are: breathing difficulty, very weak infant, and severe respitory infections.
Expression of the disease requires mutation of both alleles of the survival motor neuron gene (SMN1). Typically, the mutations are caused by a deletion within SMN1, or when the SMN1 gene is replaced by an almost identical gene called SMN2. SMN1 and SMN2 code for identical proteins, but the SMN1 gene produces the full-size protein, SMN 2 makes less amount of it. When both proteins are missing Type I SMA occurs. The milder forms of SMA occurs when SMN1 is replaced by SMN2. The more SMN2 genes an affected individual has, the more proteins they will be produce, and results in a milder form of the disease.
There is no cure for this but to reduce effect genetic conuseling is recommended.
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