RESUMEN
OBJECTIVE@#To resolve the problem of the accuracy and standardization of STR-PCR typing in forensic practice, we have designed a new method to produce standard D1S549 allelic ladder.@*METHODS@#Eight different PCR amplified D1S549 allelic fragments were isolated from the gel, eluted into the distilled water and re-amplified by PCR. The purified allelic fragments were then blunt-end subcloned individually into the pUC plasmid vectors and transfected into competent E. coli DH5 alpha cells.@*RESULTS@#The sequencing results confirmed that the size and the construe of the inserts were correct. The recombinant plasmids DNA with 8 inserts were then used as templates for re-amplification to generate D1S549 standard ladder, with which the genetic polymorphisms of D1S549 locus in Chinese Han population in chengdu, Hui population in Gansu and Wei population in Xinjiang were studied.@*CONCLUSION@#The results showed that the standard ladder made via this method is excellent, and D1S549 locus is robust for genetic research and forensic application.