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Unformatted text preview: Flourescent Short Tandem Flourescent Short Tandem Repeat (STR) Analysis Repeat (STR) Analysis Michael T. Bourke, Ph.D. Mtbbioforensic@yahoo.com Mtbbioforensic@yahoo.com CT Forensic Science Laboratory Meriden, CT Outline g122 What are STRs and how are they amplified g122 STR applications in forensics Capillary electrophoresis Analysis of DNA data using Genemapper g122 STR analysis and interpretation issues Case examples g53g72g83g72g68g87;#23#23#23g51g82g79g92g80g82g85g83g75g76g86g80g86 g53g72g83g72g68g87;#23#23#23g51g82g79g92g80g82g85g83g75g76g86g80g86 VNTR (RFLP) VNTR (RFLP) 9-40 bp 500 - 23,000 bp 2-6 bp 100 - 400 bp 8-16 bp 100 - 1,300 bp AmpFLP (D1S80) AmpFLP (D1S80) STR STR g122 Arrays of short repeats (2 Arrays of short repeats (2-7 bp) that are 7 bp) that are repeated several times in tandem repeated several times in tandem g122 >30,000 in the human genome >30,000 in the human genome g122 One every 10 kb One every 10 kb g122 Usually, variation in the number of tandem repeats that make up the array. g122 Alleles are designated by the number of repeats that they contain. Short Tandem Repeats g54 g75g82g85g87;#23#23#23 g55 g68g81g71g72g80;#23#23#23 g53 g72g83g72g68g87g86 g54 g75g82g85g87;#23#23#23 g55 g68g81g71g72g80;#23#23#23 g53 g72g83g72g68g87g86 STRs Highly discriminating Highly discriminating Abundant in genome Abundant in genome Amenable to automation Amenable to automation Discrete alleles Discrete alleles Rapid typing Rapid typing Non-isotopic Non-isotopic Low-quantity DNA Low-quantity DNA PCR-based PCR-based Degraded DNA Degraded DNA g122 SIMPLE TH01: (AATG) 5-11 g122 COMPOUND VWA: TCTA (TCTG) 3-4 (TCTA) n g122 COMPLEX D21S11: (TCTA) 4-6 (TCTG) 5-6 (TCTA) 3 TA (TCTA) 3 TCA(TCTA) 2 TCCATA (TCTA) 8-16 TC STR LOCUS TYPES STR LOCUS TYPES Advantages of STR loci over other DNA tests:-PCR Based Analysis Lower minimal quantity of input DNA < 0.2 - 0.5 ng.-Degraded DNA Smaller amplicon increases success with highly degraded samples.-High Power of Discrimination Each locus has a larger number of alleles with better allelic distribution than earlier PCR tests.-Rapid Typing Multiple STRs can be analyzed together = Multiplex Automated data acquisition and semi-automated data analysis....
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- Fall '08