[Study on the construction of DYS385 allelic ladder and the genotype distribution in two populations]

We have designed a new method to produce standard DYS385 allelic ladder in order to solve the problem of the accuracy and standardization of STR-PCR typing in forensic practice.

Nine different PCR amplified DYS385 allelic fragments were isolated from the gel, eluted into the distilled water and reamplified 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. The sequencing results confirmed that the size and the constructure of the inserts were correct. The recombinant plasmids DNA with 9 inserts were then used as templates for reamplification to generate DYS385 standard ladder.

A large quantity of standard DYS385 allelic ladder was obtained, with which the genetic polymorphisms of DYS385 locus both in Chinese Han and German populations were studied.

The STR standard ladder constructed by this method has high value in the forensic application, and the DYS385 locus is robust for forensic analysis.