Bio Options Poster-Fragile X Syndrome

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Human Anatomy

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Bio Options Poster-Fragile X Syndrome

Implications?Although a lot of attention has been given to the CGG expansion mutation of the mutated allele as the cause of fragile X (change in amino acid sequences), the epigenetic changes associated with FMR1 methylation--the silencing of the gene as well as the formation of a DNA-mRNA duplex--is the real culprit. So it cannot be classified exactly as a genetic disease and this can shed light on new treatment methods

Interaction between the RNA and DNA forms a DNA-RNA duplex that prevents the FMR1 gene to be translated. This happens between the complementary CGG-repeat portions on the transcripted mRNA and the DNA of the FMR1 gene; they are directly bound to each other to affect FMR1 transcript levels. This initiates repression of the gene but does not necessarily maintain it.

EPIGENETICS and Fragile X Mental Retardation

1. To restore FMR1 gene activity, one can target potentially reversible epigenetic changes with epigenetic modulators, primarily the DNA methylation on the CpG islands.2. Drugs like 1a can bind and stabilize the mRNA containing many CGG repeats to prevent it from binding with DNA and remove mRNA-DNA duplexes.

Fragile X Syndrome? It is the most frequently inherited mental disability, particularly in males. Both sexes can be affected by this condition, but because males only have one X chromosome, one fragile X will impact them more severely. Fragile X syndrome occurs in approximately 1 in 4,000 males and 1 in 8,000 females. People with this syndrome have severe intellectual disabilities, delayed verbal development, and autistic-like behavior.

At this threshold of 200 CGG repeats, a remarkable phenomenon occurs where the FMR1 gene itself becomes heavily CpG methylated, where methyl groups are inserted between cytosine and guanine bases at the promoter region. Chromatin marks are shifted from a euchromatic state to a fully heterochromatic state, resulting in the transcriptional silencing of FMR1 and the absence of the encoded Fragile X Mental Retardation Protein, needed for communication between brain cells. Loss of this specific protein causes fragile X syndrome.

Yang Xinyi and Angela Zhao 414

The syndrome is caused by an abnormality in the FMR1 (fragile X mental retardation 1) gene. People who do not have fragile X syndrome have 6 to 50 repeats of the trinucleotide CGG in their FMR1 gene. However, individuals with over 200 repeats have a full mutation, and they usually show symptoms of the syndrome.

REFERENCESWarren, S. (2007, November 15). The Epigenetics of Fragile X Syndrome. Cell Stem Cell. Retrieved October 15, 2014, from Influences and Disease . (n.d.). Retrieved October 12, 2014, from X syndrome: Trigger for most common form of intellectual disability and autism uncovered. (n.d.). ScienceDaily. Retrieved October 15, 2014, from Silencing in Fragile X Syndrome Explained? | ALZFORUM. (n.d.). Gene Silencing in Fragile X Syndrome Explained? | ALZFORUM. Retrieved October 15, 2014, from


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