ABSTRACT
Kinship testing in forensic casework is largely based on a likelihood ratio (LR) approach with short tandem repeat (STR) markers; however, in order to efficiently identify potential relatives in a specific population, the threshold values for kinship prediction should be determined by analyzing the kinship index distributions of the population in question. In this study, 250,000 DNA profiles were simulated using allele frequencies at 20 autosomal STR loci in Koreans, then the LRs were calculated for true close relatives and unrelated pairs. The LR distributions in related and unrelated pairs under a given relationship were compared in 2 sets of 13 Combined DNA Index System (CODIS) and 20 STR profiles. Using 13 CODIS STRs, true relatives in parent/child and full-sibling relationships were sufficiently discriminated from unrelated pairs with LR thresholds of 1,000 and 100, respectively. However, the CODIS STRs lacked the discriminatory power to differentiate between related and unrelated pairs in uncle/nephew and first cousin relationships due to high false-positive and false-negative rates with a LR threshold of 10. Increasing the number of STR loci to 20 increased discrimination of close relatives, but high false results remained in uncle/nephew and first cousin relationships. The kinship index data from this study will help make decisions on various kinship testing and familial searching in Koreans.
Subject(s)
Humans , Asian People , Discrimination, Psychological , DNA , Gene Frequency , Microsatellite RepeatsABSTRACT
The usefulness of DNA databases is well known. In Korea, many cases have been solved since the establishment of DNA databases in 2010. DNA profiles obtained from criminal evidence are analyzed and are kept in databases, and matching profile is searched. On the matching occasion, DNA databases can provide some investigative information. Close family members, for example father, son or brother, share more alleles than unrelated people. This genetic closeness can be searched using the so called familial searching, and many successful cases have been reported. Management of DNA databases including familial searching needs continuous monitoring and control, especially from ethical view points. Many different views for familial searching have been presented, and each country running DNA databases has their own different policies. We present the utility, approaches and different policies of familial searching as well as arguments for and against familial searching. We also suggest that our appropriate guidelines be mandatory and a proper administrative process be prepared for the start of familial searching.