Genetic polymorphism and variability in the Guangdong Hakka, Teochew, and Cantonese groups: A comprehensive analysis of 19 X-STRs.

Background: X chromosomeshort tandem repeat (X-STR) loci are playing an increasingly important role inforensic work, identifying female traces in male contamination and explainingcomplex kinship analyses.

Methods: In this study, we analyzed thegenetic polymorphism of 19 X-STR loci in the Guangdong Hakka, Teochew and Cantonese groups, respectively, aswell as in the Guangdong Hakka, Teochew andCantonese pooled Han. The genetic diversity and forensic characteristics of the19 X-STRs and 7 linkage groups were investigated, respectively.

Results: The experiments showed that the genetic diversity (GD) and polymorphism information content (PIC) in the pooledGuangdong Han ranged from 0.5320 to 0.9234 and 0.4369 to 0.9171, respectively, and the cumulative power of discrimination for males (PDM), power of discrimination for females (PDF) and mean paternity exclusion chance (MEC) were higher than 0.9999999, indicating that the 19 X-STRs had high geneticpolymorphism and discriminatory power. Genetic differences among Chinese Hansubgroups and among different Chinese populations were investigated byphylogenetic reconstruction and principal component analysis (PCA), respectively. Genetic analyses based on neighbor-joining (NJ) tree and principal component analysis plot showed that Cantonese, Teochew and Hakka were closely genetically related, and different populations with closer linguistic components had more genetic affinity.

Conclusions: This study adds to the forensic X-STR database and demonstrates the forensic efficiency of 19 X-STRs for the Hakka, Teochewand Cantonese populations in Guangdong, and the pooled Han of Hakka, Teochewand Cantonese people in Guangdong.