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Forensic Science Communications July 2004 – Volume 6 – Number 3
Standards and Guidelines

Report on the Current Activities of the Scientific Working Group on DNA Analysis Methods Y-STR Subcommittee

Scientific Working Group on DNA Analysis Methods Y-STR Subcommittee

Introduction

Detecting DNA from a male perpetrator is the goal in the forensic investigation of most sexual assault cases. Y-chromosome-specific STR typing targets the male DNA and is a useful additional tool in cases that often involve a mixture of male and female DNA. Although many technical aspects of Y-STR testing are parallel to autosomal STR testing, the unilateral (patrilineal) inheritance of the Y-chromosome alleles creates a haplotype of linked loci, and the statistical evaluation and reporting of the results differ significantly. Therefore, the SWGDAM Y-STR Subcommittee was established to deal with all aspects of Y-chromosome-specific testing in forensic casework.

The first meeting of the Y-STR Subcommittee convened on January 15, 2003, in Quantico, Virginia. Jack Ballantyne was elected chairman, and Mechthild Prinz was elected co-chairman.

Table 1: Y-STR Subcommittee Members

MembersLaboratories
Demris Lee Armed Forces DNA Identification, Rockville, Maryland
Gary Sims California Department of Justice, Berkeley, California
John Newman Center of Forensic Sciences, Toronto, Canada
Carl Ladd Connecticut State Police, Meriden, Connecticut
Sam Baechtel
Jill Smerick
Federal Bureau of Investigation, Quantico, Virginia
Charles Barna Michigan State Police, Lansing, Michigan
Ann Gross Minnesota Bureau of Criminal Apprehension, St. Paul, Minnesota
John Butler National Institute of Standards and Technology, Gaithersburg, Maryland
Mechthild Prinz Office of Chief Medical Examiner, New York City, New York
John Hartmann Orange County Sheriff-Coroner Department, Santa Ana, California
Phil Kinsey Oregon State Police, Portland, Oregon
Debra Figarelli Phoenix Police Department, Phoenix, Arizona
Jack Ballantyne University of Central Florida, Orlando, Florida

Adopting 11 Loci

The first official business was recommending a set of Y-STR core loci. The committee voted to adopt the 11 loci listed in Table 2. The decision was based on availability to the scientific community and the large amount of published performance and database information for most of the loci. The committee encourages further study of additional loci as to their suitability for forensic use. The first nine loci compose the European minimal haplotype complement of markers. The decision about the core loci was important to ensure data compatibility and allow for construction of appropriate population Y-STR haplotype databases.

Table 2: Adopted Loci

NumberLocusReference
1DYS19Kayser et al. 1997
2 and 3DYS385Kayser et al. 1997
4DYS389IKayser et al. 1997
5DYS389IIKayser et al. 1997
6DYS390Kayser et al. 1997
7DYS391Kayser et al. 1997
8DYS392Kayser et al. 1997
9DYS393Kayser et al. 1997
10DYS438Ayub et al. 2000
11DYS439Ayub et al. 2000

References

Kayser, M. et al. Evaluation of Y-chromosomal STRs: A multicenter study, International Journal of Legal Medicine (1997) 110(3):125-133, 141-149.

Ayub, Q. et al. Identification and characterization of novel human Y-chromosomal microsatellites from sequence database information, Nucleic Acids Research (2000) 28(2):e8.

Other Initiatives

The working group is currently developing Y-STR interpretation and reporting guidelines that will include approaches to the statistical evaluation of Y-STR haplotypes. Other projects include promoting appropriate use of Y-chromosome markers in casework and databases.