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Y-STR POLYMORPHISMS IN FORENSIC CASEWORK

Y-STR POLYMORPHISMS IN FORENSIC CASEWORK. Mgr. Jana Odlerová Institute of Forensic Science Slovak Police Corps. Y C hromosome. small ~60 Mb total DNA sequence (only chromosome 22 is smaller) - acrocentric linear DNA haploid uniparental l in e a g e s male - specific

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Y-STR POLYMORPHISMS IN FORENSIC CASEWORK

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  1. Y-STR POLYMORPHISMS IN FORENSIC CASEWORK Mgr. Jana Odlerová Institute of Forensic Science Slovak Police Corps

  2. Y Chromosome • small ~60 Mb total DNA sequence • (only chromosome 22 is smaller) • -acrocentric • linear DNA • haploid • uniparental lineages • male-specific • - genetic variation at multiple points along the Y chromosome is combined to form a Y haplotype for a sample

  3. Human X a Y Chromosome Y ch Ľudský X a Y chromozóm ~2.5 Mb on tips recombine with X (pseudoautosomal regions) ~ homologous regions onhuman X and Y chromosome exceptpseudoautosomal regions

  4. Why the Y Chromosome? • Applications - forensic investigations (98% of violent crime by men) - genealogical purposes - evolutionary studies • Advantages to Human Identity Testing • - male component isolated without differential extraction • - paternal lineages • Needs • - population studies to evaluate diversity of haplotypes • - robust assay for accurate characterization of Y markers

  5. Y Chromosome DNA Markers • STRs (microsatellites) • - DYS19, DYS385, etc. • - mostly tetranucleotide repeats • Bi-allelic markers(unique event polymorphisms--UEP) • - SNPs (single nucleotide polymorphisms) • - YAlupolymorphism (YAP) or other insertions/deletions(“indels“) • Minisatellites • - MSY1 (DYF155S1) composed of 48-114 copies of a 25 bp repeat unit with 5 sequence variant repeat types • - typed by MVR-PCR (minisatellite variant repeat)

  6. Map of Y Chromosome STR Markers

  7. Current Forensic Y STR Multiplexes Y-Plex™6 - include 6 Y-STRs (Reliagene Technologies, Inc.) Y-Plex™5 - include 5 Y-STRs (Reliagene Technologies, Inc.) PowerPlex™Y System - include 11 Y-STRs (Promega) Y-Plex™12 - include 11 Y-STRs + amelogenin (Reliagene Technologies, Inc.) AmpFLSTR Yfiler™ PCR Amplification Kit - 17 Y-STRs (Applied Biosystems)

  8. Advantages of Using Y Chromosome in Forensic Casework - limited amount of biological material(optimal is 0,3 ng DNA) - partially degraded DNA - absence of consanguineous biological relatives – parents, children - mixtures of DNA in rape cases (15 pg male DNA:150 ng female DNA) - mixtures of DNA from three or more individuals (at least one man) - male DNA present at trace levels Disadvantage– individual identification

  9. THANK YOU FOR ATTENTION

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