The Genetic Disorder Fatal Familial Insomnia

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The Genetic Disorder Fatal Familial Insomnia Fatal familial insomnia is a genetic disorder. It manifests itself by many symptoms due to the degeneration of a certain part of the brain, the thalamus. The disease also results in the formation of amyloid plaques. This is the build up of a waxy substance made of proteins associated with polysaccharides. The disease is a result of a mutation of a normal protein that is associated with brain tissue. This is the prion protein. In the case of fatal familial insomnia, the mutation occurs 178 amino acids into the normal protein. Were an asparagine should be, an aspartic acid is instead. This disease is an autosomal dominant, which means that both sexes are affected and there are no carriers. If an individual inherits the mutant gene, that individual will at some point suffer the disease. In the case of fatal familial insomnia, the affected area of the brain is the area responsible for sleep, the thalamus. The thalamus is the center which communications from the brain to the body and the body to the brain pass through for proper directions to where a signal should be received. When sleep takes place, it is thought that the thalamus becomes less efficient at this signal transfer function allowing for the vegetative state of sleep to come over an individual. Consequently, the symptoms of fatal familial insomnia are directly related to the malfunction of the responsibilities of the thalamus, namely sleep. Sleep, blood pressure, heart rate, body core temperature and hormone flow are all affected by the interruption of the body's circadian rhythms which is a direct result of the degeneration of the thalamus in this disease. Other symptoms of this disease include the inability to produce tears or feel pain as well as poor reflexes and dementia. The lack of sleep leads to other problems such as hallucinations and coma. This is a clear demonstration of a pleiotropic disease, a disease with many phenotypic expressions. That is, this disease is the result of one mutant gene yielding one mutant protein, yet causes many physical abnormalities such as skin blotches, lack of tears, etc. In the case study of an Italian family where of 288 relatives over 6 generations, 29 are affected by the disorder. The average age of onset of the disease is 49, but this may vary with the individual as with one female who was 61 years of age.

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