A 21 marker insertion deletion polymorphism panel to study biogeographic ancestry

Insertion/deletion polymorphisms have recently received increased interest in the forensic genetics community. This class of markers combines the advantageous genetic properties of single nucleotide polymorphisms (i.e., low mutation rate, genetic stability, and short amplicon size) with the technical advantage of short tandem repeat markers (simple detection by fluorescence-labelled PCR and capillary electrophoresis). For a large number of indel markers significant differences in allele frequencies between the major populations have been reported, making this class of markers suitable for the analysis of biogeographic ancestry. We have developed a multiplex PCR assay designed to establish the biogeographic ancestry of forensic DNA samples based on insertion/deletion polymorphisms. A panel of 21 short indels with allele frequency differences between three major population groups (European, African and Asian) was selected to be incorporated into a single-tube multiplex PCR assay. The assay is highly sensitive, requiring less than 0.5 ng of genomic DNA for successful typing. Due to the short fragment lengths below 200 bp, the assay is ideally suited for the typing of challenging forensic genetic case work samples. A population genetic study has been performed proving the performance of the assay in inferring the ancestral population of individuals. The chosen 21 markers are sufficient to distinguish between three major global population groups. Furthermore, the assay design leaves room for an extension in order to cover additional population groups.