Allelic and haplotype diversity of 12 X-chromosomal short tandem repeats in Koreans, with an analysis of anomalous profiles

Owing to the unique inheritance pattern of the X chromosome, X-chromosomal short tandem repeat (X-STR) analysis represents a valuable tool in forensic DNA examination-particularly in complex kinship cases, missing person investigations, and disaster victim identification. We analyzed buccal swabs from 429 unrelated Korean males for forensic statistical parameters of 12 X-STRs. Among the 427 individuals analyzed (2 were excluded), DXS10135 was the most informative marker (polymorphism information content [PIC] = 0.9131) and DXS7423 the least informative (PIC = 0.4250). When analyzed based on the four linkage groups (LGs), each individual had unique 12 X-STR haplotypes, with LG1 showing the highest haplotype diversity (0.9968) and the most common haplotype frequency (0.0164). LG1 was also the most informative (PIC = 0.9945), followed by LG3, LG4, and LG2 (with haplotype diversities of 0.9882-0.9968). Our analysis shows that Koreans clustered with East Asians, displayed strong genetic similarity, but differed significantly from Emirati Arabs, Brazilians, Argentinians, and Europeans, forming three distinct clusters influenced by historical and geographical factors. Within the examined X-STR haplotypes, biallelic patterns were identified in two instances: one involved a duplication at DXS10146, as indicated by relative peak height and normalized peak height ratio analysis, and the other encompassed eight loci, where balanced peak heights (72.51 %) and an X peak height imbalance at the amelogenin locus (59.69 %) were indicative of Klinefelter syndrome with sex chromosome aneuploidy. The 12 X-STR loci are informative and discriminatory in the Korean population, providing critical insights for forensic applications and genetic research.