Abstract
Specimens of 126 unrelated male individuals were collected from Han ethnic group in Sichuan province of China. DNA was extracted from blood specimens using Chelex 100 method (1). DNA typing was carried out by PCR. Each PCR reaction contained 2 to 20 ng human genomic DNA,1 × Taq buffer,1.5 mM MgCl2, 200 μM each nucleotide, 1.5 U Taq polymerase, 0.25 μM each primer in a total volume of 37.5 μL. In the PCR Protocol the DNA was initially denatured at 94°C for 1 min. This was followed with 94°C 50 s, 63°C 70 s, and 72°C for 7 s. A total of 38 cycles was carried out in a GenAmp PCR System 9600. The PCR products were analyzed using a horizontal nondenaturing polyacrylamide gel electrophoresis with a discontinuous buffer system (2). The gels were silverstained (3). Allele determination was carried out by comparison with the sequenced human allele ladder, which was made in-house and contained all the alleles found in this study. Following the recommendations of the International Society of Forensic Genetics (4), the allele classification for the DYS445 locus was based on the number of repeat motifs. The parameters dealing with forensic genetics were calculated according to Hou's method (5).
