Sn

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
Ludský X a Y chromozóm
2.5 Mb on tips recombine with X
(pseudoautosomal regions) homologous regions on
human X and Y chromosome except pseudoautosomal
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)
• - 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)

6
Map of Y Chromosome STR Markers
7
Current Forensic Y STR Multiplexes
Y-Plex6 - include 6 Y-STRs (Reliagene
Technologies, Inc.) Y-Plex5 - include 5 Y-STRs
(Reliagene Technologies, Inc.) PowerPlexY
System - include 11 Y-STRs (Promega) Y-Plex12 -
include 11 Y-STRs amelogenin (Reliagene
Technologies, Inc.) AmpFLSTR Yfiler PCR
Amplification Kit - 17 Y-STRs (Applied
Biosystems)

8
(No Transcript)
9
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 DNA150
ng female DNA) - mixtures of DNA from three or
more individuals (at least one man) - male DNA
present at trace levels Disadvantage
individual identification
10
(No Transcript)
11
(No Transcript)
12
THANK YOU FOR ATTENTION