Study of autosomal short tandem repeat loci using ITO method in full-sibling identification

Abstract

This study aimed to investigate the application of autosomal short tandem repeat (STR) loci using the ITO method and discriminant function algorithm for full-sibling (FS) identification. A total of 342 pairs of full siblings (FSs) and 3900 pairs of unrelated individuals (UIs) were genotyped at 51 STR loci. The groups were in accordance with discrimination power (DP) values and the number of loci, and the values of FS index (FSI) of FSs and UIs were calculated by the ITO method. The discriminant functions of FS-UI were established using the Fisher's discriminant analysis method with SPSS 19.0 software. All the lgFSI values in the FS and UI groups followed a normal distribution, and there were significant differences between the two pairs. A higher average DP value was associated with a more significant difference, as was a greater number of STR loci detected. Receiver operator characteristic curves showed that the accuracy of FS identification can be affected by both locus polymorphism and the number of loci detected. Comparing the rate of false positives and false negatives of discriminant function between the two groups, a higher average DP value and larger number of loci detected were associated with a lower rate of miscarriage of justice and were more helpful for FS-UI identification. The ITO-based discriminant analysis method has high applicability in FS-UI tests. Testing of a greater number of STR loci promotes FS identification.