Alu Elements and Human Disease

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Belzil, Camille
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Lethbridge Undergraduate Research Journal
As a family, Alu retrotransposons compose the single largest component of the human genome [2]. They are thought to have arisen from the gene coding for 7SL RNA, a component of the signal recognition particle [14, 19, 23]. The only apparent purpose of these highly repetitive sequences is to replicate and copy themselves onto new areas of the genome; this has resulted in an estimated 10% growth in human genome size since our evolutionary divergence with the chimpanzee [2]. Normally cellular proteins methylate the cytosine and guanine rich areas of these transcripts in order to prevent the retrotransposon from displacing. When cellular conditions promote demethylation, Alu regions can be transcribed and insert into new areas of the genome via an RNA intermediate [2]. Insertion into a noncoding region is typically harmless, but introduction into a coding exon can lead to disrupted gene transcription and altered protein synthesis. The original demethylation event is largely a result of environmental conditions and leads to heritable changes in DNA sequence [22]. It is estimated that Alu retrotransposition currently occurs at a rate of about 1 per every 200 births, and alone accounts for an estimated 0.1% of genetic disorders [8]. The recombination of Alu elements could potentially be one of the most important sources of genetic variation, but is also a major source of human genetic disease.
Genetic disorders--Molecular aspects , Gene mapping
Belzil, Camille (2007). Alu Elements and Human Disease. Lethbridge Undergraduate Research Journal, 2(1).