Genetic analysis of 12 X-STRs for forensic purposes in Liaoning Manchu population from China.

X-chromosomal short tandem repeats (X-STRs) have been widely used in forensic practice involving complicated cases of kinship and also play an increasingly important role in population genetics. X-STRs have been studied in regional populations of China but there is a lack of data for the Manchu population. In this study, we have investigated the forensic genetic properties of 12 X-STRs in the Investigator Argus X-12 Kit (QIAGEN, Hilden, Germany) in 772 Manchu (male = 514, female = 258) individuals from the Xiuyan and Huanren Manchu autonomous counties of Liaoning province. We observed a total of 166 alleles at 12 X-STR loci with allele frequencies ranging from 0.001295to 0.615285. The most polymorphic locus was DXS10135 with 24 alleles while DXS7423 was the least polymorphic locus with 5 alleles. We found significant linkage disequilibrium (LD) between the following pairs of markers for males: DXS10103/DXS10101, DXS10135/DXS10146, DXS10101/DXS10148, DXS10135/DXS10148, DXS7423/DXS10148 and DXS10079/DXS10148. For females, LD was only observed for DXS10103/DXS10101. The combined power of discrimination was 0.9999999979699 for males and 0.999999999999998 for females. The numbers of observed haplotypes in Manchu males were 310, 172, 182 and 172 in four linkage groups; LG1, LG2, LG3 and LG4, respectively, however, these linkage groups did not form stable haplotypes as indicated by linkage equilibrium (LE) of STRs within the groups and significant LD between the groups. This study represents an extensive report on X-STR marker variation in the Manchu population for forensic applications and population genetic studies.