COMPARISON OF VNTR ALLELE FREQUENCIES AND INCLUSION PROBABILITIES OVER 6 POPULATIONS

There is considerable debate about the methodologies used to estimate VNTR (Variable Number of Tandem Repeats) multi-locus genotype frequenc ies or odds of inclusion in forensic cases. To compare two of the meth ods in use, allele frequency distributions among six populations were compared and the effect of population heterogeneity on VNTR multi-locu s genotype frequency estimation was examined. Genotype frequencies est imated from single population data were one or two orders of magnitude smaller than those estimated by picking the highest allele frequency in a group of subpopulations to estimate genotype frequencies using a ceiling principle. The average change does not appear to be very sensi tive to the set of subpopulations used; four locus frequencies still g ive inclusion odds of one in a million or less. We think that use of t he ceiling principle solves both the statistical problem engendered by subpopulation heterogeneity and the legal problem of assuming that th e prepetrator and suspect belong to the same subpopulation. The counte rintuitive fact of human genetic polymorphism is that it is easier to identify an individual than it is to identify the subpopulation, ethni c group or race to which that individual belongs.