Population Substructure Can Significantly Affect Reliability of a DNA-led Process of Identification of Mass Fatality Victims

• NCJ Number: 219253
• Journal: Journal of Forensic Sciences Volume: 52 Issue: 4 Dated: July 2007 Pages: 874-878
• Author(s): Stjepan Kresimir Kracun B.Sc.; Goran Curic M.D.; Ivan Birus M.Sc.; Snjezana Dzijan B.Sc.; Gordan Lauc Ph.D.
• Date Published: July 2007
• Length: 5 pages
• Grant Number(s): 219-0061194-2023
• Sponsoring Agency: Croatian Ministry for Science, Education and Sport
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

In order to demonstrate the effects of inbreeding on the frequency of mini-haplotypes in subpopulations, this study analyzed the effect of population stratification on the frequency of individual alleles and mini-haplotypes in populations generated "in silico."

Abstract

After 10 generations of mating in a subpopulation of 100 individuals, each mini-haplotype was on average three times more likely than expected; however, since there was a random loss of alleles, a different number of different mini-haplotypes was created in each population. When combined into a 15-loci haplotype (which is the sole basis for determining parenthood in a single parent situation), each member of the subpopulation would be on average 250 times more likely to have a specific 15-loci haplotype than would be expected from the frequency of individual alleles. The situation would be much worse if two individuals shared some of the mini-haplotypes whose frequency was more than 10 times higher than expected. In a worst-case scenario, the probability that two independent members of the same subpopulation would share the same 15-loci haplotypes would be several orders of magnitude higher than that expected from the frequency of individual alleles. In some cases, the presence of population substructure (inbreeding) has been clearly documented, but most of the time there are no methods to determine whether an unidentified body and a potential relative belong to a specific subpopulation. Additional safeguards are needed to prevent errors in the identification process when likelihood ratio starts to approach threshold values. In the authors' work on the identifications of war victims in Croatia, they relied on other types of evidence as well as anthropological and other forensic data as a control mechanism in the DNA-lead process. Other types of evidence could include information about time, place, and other conditions of the disappearance. 3 tables, 1 figure, and 27 references