Recent insertion of an Alu element within a polymorphic human-specific Alu insertion

摘要

Alu elements are a family of short interspersed repeats that have mobilized throughout primate genomes by retrotransposition over the past 65 Myr of primate evolution (for a review, see Deininger and Batzer 1993). In the human genome, Alu elements exist in copy numbers of approximately 500,000 per haploid genome, representing approximately 5 percent of the genome, and they may be classified into groups of related subfamily members that share common diagnostic substitutions (Batzer et al. 1996b). The major subfamily branches (J, S, and Y) seem to have appeared at different evolutionary times, with J being older than S, and S being older than Y. Not only have the Alu elements contributed to the evolution of the primate genomes, but they also contribute up to 0.4 percent of human genetic disease according to Deininger and Batzer (1999). Two main mechanisms may produce human diseases: direct insertions of Alu elements within genes (0.1 percent of human genetic disease), and unequal homologous recombination events between Alu repeats (0.3 percent of human genetic disease).