ANALYSIS OF MULTIPLEXED SHORT TANDEM REPEAT (STR) SYSTEMS USING CAPILLARY ARRAY ELECTROPHORESIS

The profiling of polymorphic short tandem repeat (STR) markers is bein g applied to human identification, parentage testing and genetic mappi ng. Reliable genotyping of these markers is facilitated by polymerase chain reaction (PCR) amplification and high-resolution electrophoretic separation. Capillary array electrophoresis (CAE) offers very rapid, high-resolution separation of the amplified DNA and potential for auto mated sample processing not realized employing conventional slab-gel e lectrophoresis. The use of CAE to type DNA samples amplified at 11 gen etic loci in multiplex profiles is presented. Two sets totaling 208 sa mples were amplified in a multiplex fashion using AmpF/STR-Blue or Amp F/STR-Green I and analyzed in a blind study using CAE. With the except ion of one sample, the CAE genotyping results were in complete agreeme nt with results obtained using a single-capillary system or two slab-g el electrophoresis systems. The sample, genotype TH01 7/10, migrated s imilar to TH01 6.3/9.3 allele sizes, which suggested a potential band migration shift. The recommended approach to such an observation is to analyze the sample again. The sample was rerun and correct genotype v erified. Allelic ladder samples were analyzed multiple times by CAE to determine sizing accuracy and precision. The sizing of over 240 allel ic ladder samples yielded an average within-run precision of +/- 0.13 bp and between-run precision of +/- 0.21 bp for fragments up to 350 bp . The CAE protocols permit processing of up to 96 multiplex STR sample s in under 70 min.