Population genetic study of six closely linked groups of X-STRs in a Japanese population.

X chromosome STR (X-STR) polymorphisms are a useful tool in the fields of human population genetics and personal identification and are quite informative in the investigation of complex kinship or deficiency cases, especially where it is necessary to determine relationships with second-generation offspring in which the same X chromosome may have been inherited. We investigated eight X-STR systems using the Mentype Argus X-8 kit and further developed decaplex PCR for the DXS10148, DXS10161, DXS10160, DXS10159, DXS10079, DXS10075, DXS6799, DXS10102, DXS10106, and DXS10146 loci with the aim of constructing closely linked groups on the X chromosome. The studied population comprised 569 Japanese individuals (390 males and 179 females). Heterozygosity among the present 18 X-STRs showed a distribution of from 54.2% to 90.5%. We constructed six closely linked groups, each comprising three to five X-STRs: DXS10148- DXS10135-DXS8378, DXS10161- DXS10160-DXS10159, DXS7132-DXS10079-DXS10074-DXS10075-DXS981, DXS6809-DXS6789-DXS6799, DXS10102-HPRTB-DXS10101-DXS10106, and DXS8377-DXS10146-DXS10134-DXS7423. The forensic utility of these groups as haplotypes was then evaluated. Haplotype diversity values showed a distribution of from 0.9699 to 0.9959. Analysis of the present closely linked haplotypes will contribute to solving complex kinship cases involving X chromosome inheritance.