To detect STR genotypes of degraded DNA from decomposed tissues. The PCR apmlified products of 40 degraded DNA samples, which were purified from decomposed muscles after death for 1～6 weeks, were separated by denaturing polyacrylamide. The genotypes were analyzed by 377 DNA sequencer and 2 fluorescence-based multiplex amplification systems which contain 12 STR loci and lsex locus. The specific PCR products of 12 STR loci and 1 sex locus of the 40 samples were typed precisely and rapidly. The method described here is very useful in forensic case works, especially for the seriously degraded DNA samples.

Objective To evaluate the polymorphism and forensic applicability of Y - DNA STR locus DYS391. Method 111 unrelated male samples from Guangzhou Han population were investigated.DYS391 primer was labeled with FAM. PCR products were detected using denatured PAGE with GenScan Software on the ABI Prism 377 DNA sequencer.Results Frequency data of 3 different DYS391 alleles were obtained. Conclusion The results demonstrated that the DYS391 locus is of high human specificity. No mutation was found.