Internet Accessible Population Databases: YHRD and EMPOP

Frequencies are important to attach numerical strength to a match between any kinds of genetic profiles. Therefore, the allele distributions within discrete populations must be reported for every new generation of polymorphic markers. Since the discovery of blood groups, population data have been published on paper, but with the triumph of the DNA technology, population data need to be propagated via a more accessible and capacious medium, the Internet. Naturally, nowadays, the most widely used genetic system, the STRs, is well described in terms of population genetics and its allele frequencies have been made available in the World Wide Web. Also, lineage (or haploid) markers as the Y chromosome and the mitochondrial DNA (mtDNA) must be analyzed within a statistical framework and population data are mandatory to perform calculations. Owing to the lack of recombination and linear mode of inheritance, both the sampling strategy and the reporting of frequencies differ from autosomal DNA markers but follow the same principles based on population genetics theory and laws of probability. Here, we present the two major Internet accessible database projects for linear markers, YHRD and EMPOP. These tightly curated and quality-controlled forensic databases are designed to store haplotypes from hundreds of population samples from around the globe and to rapidly disseminate haplotype frequency data via the Internet to forensic analysts. The databases also include several tools to analyze population substructure effects, to interpret matches between Y-STR and mtDNA profiles, to attach likelihood ratios in mixture analyses, and to formulate valid forensic testimonies.