Genetic Polymorphism Investigation of 19 X‑STR Loci in the Han Population in Northern China

To investigate the genetic polymorphisms of 19 X‑STR loci in the Han population in Northern China,samples from 628 unrelated individuals(314 males and 314 females)were collected and 19 X‑STR loci were amplified by AGCU X19 STR System.A total of 270 different alleles were detected in 19 X‑STR loci.All loci were in Hardy−Weinberg equilibrium and there was only one pair of linkage loci(DXS10103‑DXS10101).There was no significant difference in allele frequency between male and female populations.The combined power of discrimination in males was 1–1.8667×10−13,while the combined power of discrimination in females was 1–3.6532×10−22.The combined mean paternity exclusion chance(CMEC)for X-chromosomal markers in father/daughter or mother/son duos Mean paternity exclusion chance(MECDesmarais Duo)was 1–5.1109×10−9.Moreover,the CMEC for X-chromosomal markers in trios involving daughters(MECDesmarais)was 1–2.0292×10−12.The compound amplification system composed of 19 X‑STR in this study showed high polymorphism in the Han population of Northern China,which had a high application value in difficult genetic relationship identification.

Identification of Half‑Sisters from Different Mothers by Autosomal and X Chromosomal Short Tandem Repeats:A Case Study

Complex kinship identification such as half‑sibling identification is a difficult task in forensic biology Here we represented an approach in dealing with half‑sisters from different mothers,with the combination of autosomal and X chromosomal short‑tandem repeats(STRs)data.X chromosomal STRs can offer additional information,especially in some cases where autosomal STRs alone may not provide enough information for an accurate opinion.In this case,half‑sister or unrelated relationship between two women(S_(1)and S_(2))with different mothers were distinguished.23 autosomal and 31 X chromosomal STRs of S_(1),S_(2),S_(1)’s mother(M1),S_(2)’s mother(M2)and S_(1)’s grandmother(G1)were profiled with three different commercial kits.As to X‑chromosome STRs,likelihood ratios(LRs)were calculated by FamLinkX with consideration of linkage,linkage disequilibrium,and mutations.When only the profiles of the two individuals(S_(1)and S_(2))were available,LRs between S_(1)and S_(2)were 1.1110×10^(2)based on 23 autosomal STRs and 3.2257 om107 based on 31 X chromosomal STRs.When the maternal genotypes were taken into consideration,LRs increased to 2.5297×10^(3)and 3.0563×10^(18).Therefore,both the DNA profiles of each mothers and X chromosomal STRs are important in dealing with the identification of half‑sisters from different mothers.

Study of Autosomal Short Tandem Repeat Loci Using ITO Method in Full‑Sibling Identification

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.

Genetic Diversities of 23 Y‑Chromosome Short Tandem Repeat Loci in a Han Population in the Beijing Region

We investigated the polymorphisms of 23 Y‑short tandem repeat(STR)loci in a Han population in the Beijing region.Blood samples were collected from 255 unrelated Han males.DNA templates were amplified using the PowerPlex®Y23 system,and the amplification products were detected with a 3130 genetic analyzer.A total of 254 haplotypes were detected from the 255 unrelated Han males in the Beijing region.The gene diversity of these 23 Y‑STR loci was 0.3952–0.9721.The haplotype diversity was 0.99996 and discrimination capacity(DC)was more than 99.6%.The 23 Y‑STR loci used in this study are highly polymorphic in Han individuals in the Beijing region and are therefore suitable for paternal kinship identification.Studying allelic deletions such as DYS448 and DYS549 are important for examining Y‑STR polymorphisms and forensic testing.