Evaluation of Detection Efficiency for Trio Full Sibling Testing / 法医学杂志

OBJECTIVES@#To study the detection efficiency of trio full sibling with another known full sibling reference added under different number of autosomal STR typing systems.@*METHODS@#Based on 43 detection systems consisting of 13 to 55 representative autosomal STR loci, 10 000 true families (full sibling group) and 10 000 false families (unrelated individual group) were randomly simulated. The full sibling index (FSI) was calculated based on the method of family reconstruction. The cumulative sibling relationship index (CFSI) of 0.000 1 and 10 000 were used as the evaluation thresholds, and the detection efficiency parameters were calculated and compared with the identification of the duo full sibling testing.@*RESULTS@#With the increasing number of STR loci, the error rate and inability of judgement rate gradually decreased; the sensitivity, specificity, correct rate of judgment and other parameters gradually increased, and the system efficiency gradually improved. Under the same detection system, trio full sibling testing showed higher sensitivity, specificity, system efficiency and lower inability of judgement rate compared with duo full sibling testing. When the system efficiency was higher than 0.85 and inability of judgement rate was less than 0.01%, at least 20 STRs should be detected for trio full sibling testing, which was less than 29 STRs required by duo full sibling testing.@*CONCLUSIONS@#The detection efficiency of trio full sibling testing is superior to that of duo full sibling testing with the same detection system, which is an effective identification scheme for laboratories with inadequate detection systems or for materials with limited conditions.

Ancestry Inference Using the ForenSeqTM DNA Signature Prep Kit / 法医学杂志

Objective To evaluate the effect of 56 ancestry informative single nucleotide polymorphism （aiSNP） genetic markers in the ForenSeqTM DNA Signature Prep Kit on ancestry inference. Methods A total of 85 samples from five populations including Hebei Han population, Inner Mongolia autonomous region Mongolian population, Tibet autonomous region Tibetan population, Xinjiang Uygur autonomous region Uygur population and Nigerian population were collected. The library was constructed with the ForenSeqTM DNA Signature Prep Kit and sequencing was performed based on the MiSeq FGx Forensic Genomics System. Using universal analysis software （UAS） of ForenSeqTM, principal component analysis （PCA）, Structure and likelihood ratio method was used on the genotyping data of 56 aiSNP markers, respectively, and the genetic relationships between populations and inference of the origin of ancestors were analyzed. Results Among the five populations tested, the four ethnic populations in China （Hebei Han population, Inner Mongolia autonomous region Mongolian population, Tibet autonomous region Tibetan population and Xinjiang Uygur autonomous region Uygur population） could be significantly distinguished from Nigerian population. Xinjiang Uygur autonomous region Uygur individuals were shown as having mixed origins of ancestors and could be distinguished from the other three Chinese populations. However, the other three populations in China （Hebei Han population, Inner Mongolia autonomous region Mongolian population and Tibet autonomous region Tibetan population） could not be effectively distinguished by the system. Conclusion The 56 aiSNP markers in the ForenSeqTM DNA Signature Prep Kit can make accurate ancestry inference from the intercontinental level, but it is not yet able to distinguish between Chinese subpopulations.

Full Sibling Identification by IBS Scoring Method and Establishment of the Query Table of Its Critical Value / 法医学杂志

OBJECTIVES@#To establish a query table of IBS critical value and identification power for the detection systems with different numbers of STR loci under different false judgment standards.@*METHODS@#Samples of 267 pairs of full siblings and 360 pairs of unrelated individuals were collected and 19 autosomal STR loci were genotyped by Goldeneye™ 20A system. The full siblings were determined using IBS scoring method according to the 'Regulation for biological full sibling testing'. The critical values and identification power for the detection systems with different numbers of STR loci under different false judgment standards were calculated by theoretical methods.@*RESULTS@#According to the formal IBS scoring criteria, the identification power of full siblings and unrelated individuals was 0.764 0 and the rate of false judgment was 0. The results of theoretical calculation were consistent with that of sample observation. The query table of IBS critical value for identification of full sibling detection systems with different numbers of STR loci was successfully established.@*CONCLUSIONS@#The IBS scoring method defined by the regulation has high detection efficiency and low false judgment rate, which provides a relatively conservative result. The query table of IBS critical value for identification of full sibling detection systems with different numbers of STR loci provides an important reference data for the result judgment of full sibling testing and owns a considerable practical value.