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[Allele sequences and population genetics of pentanucleotide tandem repeat D6S957]
1West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan, 610041 P.R. China. rechtsme@wcums.edu.cn
Objective:
Pentanucleotide tandem repeat loci are useful markers of short tandem repeat (STR) for genetic analysis. We focused on the analysis of the DNA sequence for each allele at the pentanucleotide STR locus D6S957 in order to understand their structures in the human genome and to construct human allelic ladder, which is necessary for forensic DNA typing. In order to evaluate the forensic applicability of D6S957, we investigated the genotype distributions and allele frequencies in major ethnic groups.
Methods:
A total of 230 samples from unrelated individuals were analyzed by PCR. Allele determination was carried out by comparison with a sequenced human allelic ladder made in-house. An example of each allele was sequenced on an ABI 377 automated sequencer.
Results:
This pentanucleotide STR exhibited a minimal amount of stutter and provided easily interpretable results. Eight alleles were found in these populations. No evidence of deviation from Hardy-Weinberg equilibrium was observed. In 64 confirmed father/mother/child triplets no mutation events were observed. The mutation rate was indirectly estimated at 2.5 x 10(-5) using a maximum likelihood method.
Conclusion:
D6S957 is a useful marker for forensic casework and paternity analysis.