Abstract: Objective To investigate the alleles and genotypes frequency of 6 short tandem repeat (STR)loci (DXS8378、DXS7132、DXS6789、DXS101、HPRTB and DXS7423) on the X chromosome in Han popu-lation. Methods The six X- chromosome STR loci were analyzed by PCR following polyacylamide gel elec-trophoresis and silver stain. Results Among 120 females from Xi′an Han population, the number of allelesin the 6 loci (DXS8378、DXS7132、DXS6789、DXS101、HPRTB and DXS7423) were 5,6,11,10,8,and 4 re-spectively; the number of genotypes in the 6 loci were 10,17,29,32,22,and 7 respectively; Exact testsdemonstrated genotype frequencies in females had no departure from Hardy- Weinberg equilibrium. Con-clusion The six X- chromosome STR loci are appropriate for individual identification, paternity testing in-volving a female child and for study on related disease.

Key words: x-chromosome, STR, polymorphism