Volume 46, Issue 5 (September 2001)
Allele Frequencies of Pentanucleotide STR D6S957 in Chinese and German Populations
Specimens were obtained from 99 Germans (Bremen, Germany) and 131 Chinese (Chengdu, Sichuan province, China), who were unrelated volunteer blood donors. DNA was extracted using the Chelex method (1). DNA Typing was carried out by PCR. Amplification primers for D6S957 locus were published in GDB, which were designed by the Utah marker development group (2). Each PCR reaction contained 2 to 40 ng human genomic DNA, 1x 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 5 min. This was followed with 94°C for 40 s, 60°C for 50 s and 72°C for 1 min. A total of 30 cycles was carried out in a GeneAmp PCR System 9600. The PCR products were analyzed using a horizontal nondenaturing polyacrylamide gel electrophoresis with a discontinuous buffer system (3). The gels were silverstained (4). 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 Haemogenetics (5), the allele classification for the D6S957 locus was based on the number of repeat motifs. A modified X2-test (6) was used to verify whether the genotype distribution conformed to Hardy-Weinberg equilibrium predictions. All other parameters dealing with forensic genetics were calculated with a computer program POWERSTATS (7).