The Cause And Effects Of Rett Syndrome (RTT)

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This report breaks down Rett Syndrome (RTT) in order to inform and educate patients and their family members on the genetic and symptomatic components. To begin, RTT is a post-natal neurodevelopmental condition that almost exclusively affects females. Its characteristic symptoms include an initial normal development followed by a period of regression where the child loses the ability to perform motor functions and may exhibit autistic-like symptoms. The regression period is followed by a plateau of motor deterioration that can last for decades. Furthermore, the syndrome is believed to be X-linked and fatal in males. The rest of this report will go into further details about the cause and effect of Rett Syndrome.
Genetic Foundation
Normal Function
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The type of mutation varies between cases, and there is no definitive genetic mutation for the syndrome. The mutations are believed to arise de novo in the paternal germline. This means that the alteration of the gene is present for the first time in the family member as a result of a mutation in the sperm cell of the father. Frameshift, missense, and nonsense mutations are the proposed point mutations that lead to MECP2 alterations (Chahrour, M., Huda, Z. 2007). Point mutations are caused by a single nucleotide being substituted, added, or deleted in the DNA. The first suggested point mutation is a missense mutation, where a single nucleotide is substituted, which can lead to a different amino acid being made and a change in the protein. The second possible mutation is a nonsense mutation, where a point mutation results in an incomplete protein that is non-functional. The final mutation is a frameshift, where insertion or deletion of a nucleotide changes how the DNA is read and results in an altered protein (Liu, H. et al 2001). More potential mutations are currently being …show more content…
2007). The mutations render the transcriptional repressor dysfunctional, and therefore MECP2 is not able to ‘turn off’ genes that are normally turned off during development. This leads to an imbalance in gene expression in the brain, which can have vast neuron impacts and can reduce overall neuronal activity (Chahrour, M., Huda, Z. 2007). Specifically, a study found a decrease in the functional units of the brain, reduced dendrite branching, and shorted and sparse dendrites in the frontal cortex (Neul et al. 2010). Dendrites extend from neurons and their shape is important in processing information in the brain (Harris, K., Spacek, J. 2016). Therefore, it is hypothesized that a reduction in dendrite branching, abundance, and length has a negative impact on neurodevelopment. In addition, since MECP2 increases in abundance post-natal, its dysfunction has the largest impact on post-natal development and can lead to neurodevelopmental abnormalities (Neul et al. 2010). In sum, MECP2 mutations have the largest impact on proper brain development.
Inheritance of Mutations Rett Syndrome is almost exclusively seen within females. Researchers found the syndrome to be X-linked dominant with lethality in males (Amir et al. 1999). The MECP2 gene is found on the X chromosome, however it is rarely inherited from parent

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