[Genotyping and linkage disequilibrium analysis of 67 SNP loci on X chromosome]

To screen a panel of SNP loci on X chromosome (X-SNP loci) that is informative in Chinese Han population and evaluate its potential value in forensic identification.

Sixty-seven candidate X-SNP loci were selected according to the information on dbSNP and HapMap. Genomic DNA extracted from blood samples of 428 unrelated Chinese Han individuals were analyzed through multiplex amplification followed by matrix assisted laser desorption/ionization time-of-flight mass spectrometry, and allele frequencies of the 67 X-SNP loci were calculated. In view of the population data and situation of linkage disequilibrium, X-SNP markers promising in forensic identification were sorted out.

Population data of the 67 X-SNP loci were obtained. Except rs12849634, no deviations from Hardy-Weinberg equilibrium could be found. Of the rest 66 X-SNP loci, two loci (rs1229078 and rs1544545) were found to be low informative (minor allele frequency < 0.3). Closely linked alleles were observed at six pairs of X-SNP loci and slightly linked alleles were observed at two pairs of X-SNP loci. Fifty-two X-SNP loci showing independent inheritance and high polymorphisms were finally selected. The markers were promising in forensic identification. CPE in trio and duo cases were 0.999 999 999 96 and 0.999 999 5, respectively. CDP in female and male populations were 0.999 999 999 999 999 999 999 84 and 0.999 999 999 999 999 31, respectively.

A panel of 52 informative X-SNP loci showing independent inheritance is selected. These markers meet the needs of individual identification and relationship testing in judicially disputed cases.