Key Points
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Alu elements are a class of short interspersed elements (SINEs) that have expanded to a copy number of more than one million elements in primate genomes.
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The expansion of Alu elements is characterized by the dispersal, in a series of subfamilies, of elements of different evolutionary age that share common nucleotide substitutions.
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Alu elements have an impact on the genome in several ways, including insertion mutations, recombination between elements, gene conversion and gene expression.
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The human diseases caused by Alu insertions include neurofibromatosis, haemophilia, familial hypercholesterolaemia, breast cancer, insulin-resistant diabetes type II and Ewing sarcoma.
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Alu elements alter the distribution of methylation and, possibly, transcription of genes throughout the genome.
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The transcription of Alu elements changes in response to cellular stress and might be involved in maintaining or regulating the cellular stress response.
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Alu elements are a primary source for the origin of simple sequence repeats in primate genomes.
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Alu-insertion polymorphisms are a boon for the study of human population genetics and primate comparative genomics because they are neutral, identical-by-descent genetic markers with known ancestral states.
Abstract
During the past 65 million years, Alu elements have propagated to more than one million copies in primate genomes, which has resulted in the generation of a series of Alu subfamilies of different ages. Alu elements affect the genome in several ways, causing insertion mutations, recombination between elements, gene conversion and alterations in gene expression. Alu-insertion polymorphisms are a boon for the study of human population genetics and primate comparative genomics because they are neutral genetic markers of identical descent with known ancestral states.
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Acknowledgements
Research on mobile elements in the Batzer and Deininger labs is supported by the National Institutes of Health, Department of the Army, Louisiana Board of Regents Millennium Trust Health Excellence Fund and the Office of Justice Programs, National Institute of Justice, Department of Justice. The points of view in this document are those of the authors and do not necessarily represent the official position of the US Department of Justice.
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DATABASES
LocusLink
CMP-N-acetylneuraminic acid hydroxylase
OMIM
familial hypercholesterolaemia
insulin-resistant diabetes type II
FURTHER INFORMATION
Glossary
- MICROSATELLITE
-
A class of repetitive DNA that is made up of repeats that are 2–8 nucleotides in length. They can be highly polymorphic and are frequently used as molecular markers in population genetics studies.
- MINISATELLITE
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A class of repetitive sequences, 7–100 nucleotides each, that span 500–20,000 bp, and are especially located throughout the genome, towards chromosome ends.
- PSEUDOGENE
-
A DNA sequence that was derived originally from a functional protein-coding gene that has lost its function owing to the presence of one or more inactivating mutations.
- RENATURATION CURVE
-
A plot of DNA annealing as a function of DNA concentration and time. The amount of DNA (as a percentage) that has renatured (reassociated/reannealed) plotted against 'C0t', where 'C0' refers to the initial DNA concentration and 't' is the time of renaturation.
- PAIRWISE DIVERGENCE
-
The number of nucleotide differences between two aligned DNA sequences.
- ORTHOLOGOUS GENES
-
Loci in two species that are derived from a common ancestral locus by a speciation event. This is different from paralogous members of a gene family that are derived from duplication events.
- GENETIC DRIFT
-
Random changes in allele frequency that result from the sampling of gametes from generation to generation.
- HOMOPLASY
-
Similarity due to independent evolutionary change; an allelic variant (such as a nucleotide variant or a mobile-element insertion at a particular location) that is present in two or more genes, but absent in their common ancestor.
- TROPOELASTIN
-
The soluble precursor of elastin (one of the most hydrophobic proteins known). Mammalian tropoelastin is a moderately conserved protein.
- LOSS OF HETEROZYGOSITY
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(LOH). A loss of one of the alleles at a given locus as a result of a genomic change, such as mitotic deletion, gene conversion or chromosome missegregration.
- GENE CONVERSION
-
A non-reciprocal recombination process that results in an alteration of the sequence of a gene to that of its homologue during meiosis.
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Batzer, M., Deininger, P. Alu repeats and human genomic diversity. Nat Rev Genet 3, 370–379 (2002). https://doi.org/10.1038/nrg798
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DOI: https://doi.org/10.1038/nrg798
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