title: Active human retrotransposons: variation and disease.
abstract: Mobile DNAs, also known as transposons or 'jumping genes', are widespread in nature and comprise an estimated 45% of the human genome. Transposons are divided into two general classes based on their transposition intermediate (DNA or RNA). Only one subclass, the non-LTR retrotransposons, which includes the Long INterspersed Element-1 (LINE-1 or L1), is currently active in humans as indicated by 96 disease-causing insertions. The autonomous LINE-1 is capable of retrotransposing not only a copy of its own RNA in cis but also other RNAs (Alu, SINE-VNTR-Alu (SVA), U6) in trans to new genomic locations through an element encoded reverse transcriptase. L1 can also retrotranspose cellular mRNAs, resulting in processed pseudogene formation. Here, we highlight recent reports that update our understanding of human L1 retrotransposition and their role in disease. Finally we discuss studies that provide insights into the past and current activity of these retrotransposons, and shed light on not just when, but where, retrotransposition occurs and its part in genetic variation.
authors.affiliation: McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, United States.
authors.forename: Dustin C
authors.initials: DC
authors.lastname: Hancks
authors.forename: Haig H
authors.initials: HH
authors.lastname: Kazazian
mesh_terms: D020087:Alu Elements; D019175:DNA Methylation; D004251:DNA Transposable Elements; D030342:Genetic Diseases, Inborn / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism; D014644:Genetic Variation; D015894:Genome, Human; D006801:Humans; D020084:Long Interspersed Nucleotide Elements; D016366:Open Reading Frames; D011401:Promoter Regions, Genetic; D011544:Pseudogenes; D012313:RNA / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic; D020506:Untranslated Regions
chemical_list: D004251:DNA Transposable Elements; D020506:Untranslated Regions; D012313:RNA