Interspersed repeat insertion polymorphisms for studies of human molecular anthropology

The recent insertion of mobile elements, of the Alu and L1 families, in the human genome provides a distinct class of polymorphism in the human genome. Because the insertion of these elements in the genome is so rare and once they are inserted they are stable; they represent a unique group of markers that are identical by descent. This type of marker is among the most informative in ascertaining relationships between individuals and populations. The assays for these markers are extremely robust, easy to perform, and readily adaptable to mass analysis and automation. In addition, as the insertion alleles are all newly arisen, the ancestral allele is always the allele missing the insertion. This information allows estimations of the roots of trees, which are not possible with all types of markers. The greatest potential for these markers is with upcoming developments that will allow the identification of new insertions in many different genomes simultaneously. These procedures will allow investigators to isolate markers that are particularly informative for specific populations and allow development of panels of markers tailored for particular populations.