y-str polymorphisms in forensic casework
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
Y-STR POLYMORPHISMS IN
FORENSIC CASEWORK
Mgr. Jana Odlerová
Institute of Forensic Science Slovak Police Corps
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
Y ch
Ľudský X a Y chromozóm
Human X a Y Chromosome
~ 2.5 Mb on tips recombine with X (pseudoautosomal regions)
~ homologous regions on human X and Y chromosome except pseudoautosomal regions
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
Y Chromosome DNA Markers
• STRs (microsatellites) - DYS19, DYS385, etc. - mostly tetranucleotide repeats
• Bi-allelic markers (unique event polymorphisms--UEP)
- SNPs (single nucleotide polymorphisms) - Y Alu polymorphism (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)
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)
Current Forensic Y STR Multiplexes
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