Inference of human geographic origins using Alu insertion polymorphisms

David A. Ray, Louisiana State University
Jerilyn A. Walker, Louisiana State University
Ashley Hall, University of Central Florida
Barbara Llewellyn, Illinois State Police
Jack Ballantyne, University of Central Florida
Allen T. Christian, Lawrence Livermore National Laboratory
Kenneth Turteltaub, Lawrence Livermore National Laboratory
Mark A. Batzer, Louisiana State University


The inference of an individual's geographic ancestry or origin can be critical in narrowing the field of potential suspects in a criminal investigation. Most current technologies rely on single nucleotide polymorphism (SNP) genotypes to accomplish this task. However, SNPs can introduce homoplasy into an analysis since they can be identical-by-state. We introduce the use of insertion polymorphisms based on short interspersed elements (SINEs) as a potential alternative to SNPs. SINE polymorphisms are identical-by-descent, essentially homoplasy-free, and inexpensive to genotype using a variety of approaches. Herein, we present results of a blind study using 100 Alu insertion polymorphisms to infer the geographic ancestry of 18 unknown individuals from a variety of geographic locations. Using a Structure analysis of the Alu insertion polymorphism-based genotypes, we were able to correctly infer the geographic affiliation of all 18 unknown human individuals with high levels of confidence. This technique to infer the geographic affiliation of unknown human DNA samples will be a useful tool in forensic genomics. © 2004 Elsevier Ireland Ltd. All rights reserved.