title: [Study on the construction of standard D12S391 allelic ladder and its genetic polymorphism in six populations].
abstract: OBJECTIVE
  To resolve the problem of the accuracy and standardization of short tandem repeat-polymerase chain reaction (STR-PCR) typing in forensic practice, the authors have designed a new method of producing standard D12S391 allelic ladder.
  
  
  METHODS
  Nine different PCR amplified D12S391 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(TM) cells. The sequencing results confirmed that the size and the structure of the inserts were correct. The recombinant plasmids DNA with 9 inserts were then used as templates for PCR re-amplification to generate D12S391 standard ladder.
  
  
  RESULTS
  With the ladder, the authors studied the genetic polymorphisms of D12S391 locus in six populations (German, Japanese and Chinese south-western Han, northern Han, Weiwu'er and Hui populations), and the respective primary data in the six populations were obtained. D12S391 locus showed high polymorphism in all six populations, and its exclusion power and discrimination power are 0.609-0.786 and 0.940-0.952 respectively.
  
  
  CONCLUSIONS
  The results demonstrate that the standard ladder generated via this method is excellent, and D12S391 locus is robust for genetic research and forensic application.
authors.affiliation: West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan, 610041 P. R. China.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.forename: Junping
authors.initials: J
authors.lastname: Xin
authors.forename: Guodi
authors.initials: G
authors.lastname: Chen
authors.forename: Miao
authors.initials: M
authors.lastname: Liao
authors.forename: Ronghua
authors.initials: R
authors.lastname: Li
mesh_terms: D000483:Alleles; D044466:Asian People / Q000235:genetics; D002681:China; D005554:Forensic Medicine; D005828:Genetics, Population; D005858:Germany; D006801:Humans; D007564:Japan; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D020080:Tandem Repeat Sequences / Q000235:genetics*; D044465:White People / Q000235:genetics