Genetic polymorphism and haplotype analysis of 4 tightly linked X-STR duos in Koreans.

AIM To investigate genetic polymorphism and haplotypes of tightly linked X-chromosomal short tandem repeat (X-STR) clusters in Koreans. METHODS Four X-STR duos in the linkage group 1-4 (DXS10135-DXS8378, DXS7132-DXS10074, HPRTB-DXS10101, and DXS10134-DXS7423) were investigated in 450 unrelated Koreans (300 men and 150 women) using the Mentype Argus X-8 Polymerase Chain Reaction Amplification Kit. RESULTS No significant deviation from Hardy-Weinberg equilibrium was observed in any of the 8 loci. DXS10135 was the most polymorphic X-STRs, with 25 alleles and DXS7423 was the least informative, with 5 alleles. Eleven off-ladder alleles and a triallelic pattern were observed, and these alleles were characterized by cloning and sequencing analysis. In 300 Korean men, 38 to 59 haplotypes were observed for each linkage duo with 91.6-96.6% of haplotype diversities. However, due to the low genetic diversity of DXS7423, the X-STR duo in linkage group 4 (DXS10134-DXS7423), in comparison with other linkage duos, had considerably lower haplotype diversity values (91.6%) with 3 common haplotypes (35-15, 36-15, and 37-15) observed in 44.3% of Koreans. CONCLUSION Four X-STR duos in the linkage group 1-4 will be able to provide a powerful tool for solving complex kinship cases in Koreans. However, to increase the haplotype diversity in the linkage group 4, it will be useful to discover a new marker for Asians that can serve as an adequate substitute for DXS7423 or at least complement the existing linkage duo of DXS10134-DXS7423.