Chapter 19: Y-STR Profiling and Gender Typing

 Y chromosome inherited by the father  Unique to males  Y-STR  Sexual assault investigations w/ male suspects  Mixtures  Number of perpetrators  Paternal lineage can be est.  Missing person cases Forensic Biology by Richard Li2

 Disadvantages of Y-STR  Discriminating power are low  Product rule does not apply  Cannot distinguish individuals with the same paternal lineage Forensic Biology by Richard Li3

 60 million base pairs  Two regions:  Psuedo-Autosomal Region (PAR)  Male Specific Region Y (MSY)  Repetitive elements:  STRs  Alu  LINE  SNPs Forensic Biology by Richard Li4

 400 STR loci have been identified  Majority on long arm (60%)  22% on short arm  Core repeat sizes:  9% dimeric, 39% trimeric, 45% tetrameric, 9% pentameric, 1% hexameric  Haplotype- collection of alleles that are linked Forensic Biology by Richard Li5

 European Minimal Haplotype (EMH)  1997  Core set of nine loci  DYS19, DYS385a/b, DYS389I, DYS389II, DYS390, DYS391, DY5392, DY5393  U.S. Haplotype  2003  SWGDAM  EMH set plus tow additional loci: DYS438 & DYS439 Forensic Biology by Richard Li6

 Y-STR in forensic casework started in Europe  Office of Chief Medical Examiner in NYC  Facilitated by commercially available kits  Y-PLEX 6 Forensic Biology by Richard Li7

 Victim identification & Sexual assault cases  Amelogenin (AMEL) marker used  AMELX & AMELY  AMELY null mutations Forensic Biology by Richard Li8