A novel strategy for sibship determination in trio sibling model.
OBJECTIVE
To use a virtually simulated population, generated from published allele frequencies based on 15 short tandem repeats (STR), to evaluate the efficacy of trio sibship testing and sibling assignment for forensic purposes.


METHODS
Virtual populations were generated using 15 STR loci to create a large number of related and unrelated genotypes (10,000 trio combinations). Using these virtual populations, the probability of related and unrelated profiles can be compared to determine the chance of inclusions of being siblings if they are true siblings and the chance of inclusion if they are unrelated. Two specific relationships were tested - two reference siblings were compared to a third true sibling (3S trio, sibling trio) and two reference siblings were compared to an unrelated individual (2S1U trio, non-sibling trio).


RESULTS
When the likelihood ratio was greater than 1, 99.87% of siblings in the 3S trio population were considered as siblings (sensitivity); 99.88% of non-siblings in the 2S1U trio population were considered as non-siblings (specificity); 99.9% of both populations were identified correctly as siblings and non-siblings; and the accuracy of the test was 99.88%.


CONCLUSIONS
The high sensitivity and specificity figures when using two known siblings compared to a putative sibling are significantly greater than when using only one known relative. The data also support the use of increasing number of loci allowing for greater confidence in genetic identification. The system established in this study could be used as the model for evaluating and simulating the cases with multiple relatives.
Department of Forensic Science, Central Police University, 56 Shu-Jen Road, Kwei-San, Taoyuan 33304, Taiwan ROC.
James Chun-I
JC
Lee
Yen-Yang
YY
Lin
Li-Chin
LC
Tsai
Chun-Yen
CY
Lin
Tsun-Ying
TY
Huang
Pao-Ching
PC
Chu
Yu-Jen
YJ
Yu
Adrian
A
Linacre
Hsing-Mei
HM
Hsieh
D003198:Computer Simulation; D016172:DNA Fingerprinting; D018732:Forensic Anthropology / Q000379:methods*; D006801:Humans; D016013:Likelihood Functions; D018895:Microsatellite Repeats; D008957:Models, Genetic; D012680:Sensitivity and Specificity