PopAffiliator: online calculator for individual affiliation to a major population group based on 17 autosomal STR genotype profile

Abstract

Because of their sensitivity and high level of discrimination, short tandem repeat (STR) maker systems are currently the method of choice in routine forensic casework and data banking, usually in multiplexes up to15-17 loci. Constraints related to sample amount and quality, frequently encountered in forensic casework, willnot allow to change this picture in the near future, notwithstanding the technological developments. In thisstudy, we present a free online calculator named PopAffiliator (http://cracs.fc.up.pt/popaffiliator) for individual population affiliation in the three main population groups, Eurasian, East Asian and sub-Saharan African, based ongenotype profiles for the common set of STRs used inforensics. This calculator performs affiliation based on amodel constructed using machine learning techniques. Themodel was constructed using a data set of approximatelyfifteen thousand individuals collected for this work. Theaccuracy of individual population affiliation is approximately86%, showing that the common set of STRs routinely used in forensics provide a considerable amount of information for population assignment, in addition to being excellent for individual identification.