Mechtild Prinz, Mary Hyde, Howard Baum and Robert Shaler
Department of Forensic Biology, Office of the Chief Medical Examiner, New York, NY

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Due to the specificity of the primer annealing reaction, Y-chromosome specific polymorphisms can be detected before a high background of female DNA (Prinz et al. submitted), which is advantageous for forensic casework.

In order to evaluate the significance of an inclusion with Y specific STRs, it is necessary to establish haplotype frequencies for different populations.

The Y-chromosome specific STRs, DYS19, DYS389 I and II, DYS390 (Roewer et al. forthcoming) were typed for Hispanic (n=88), African American (n=81) and Asian (n=25) individuals from the New York City area. DYS389 I and II are two polymorphic loci on the Y-chromosome that are simultaneously amplified using one pair of primers. Therefore, a combination of three primer pairs resulted in the multiplex detection of four loci. Alleles were detected by PCR with fluorescently labeled primers and separation on a 373 A Sequencer (ABD/PE).

Allele frequencies and allele distributions show significant differences between the three populations. Haplotype analysis for DYS19, DYS389 I and II and DYS390 revealed a total of 89 haplotypes in 194 male individuals. No haplotype was shared by all three ethnic groups. Hispanics and African Americans shared 19 haplotypes, Hispanics and Asians shared 3 haplotypes. The Asians also showed one haplotype that had been observed in African Americans. The most common haplotype occurred 19 times in 194 individuals. 63% of all observed haplotypes occurred only once in the tested population sample. This number of unique haplotypes will increase after the other available Y-chromosome specific STRs have been included in the haplotype analysis.

Even the evaluation of an inclusion for Y-chromosome specific STRs will pose similar problems as are being faced for mitochondrial DNA analysis, e.g. importance of mutation rates, size of database, shared haplotypes for relatives. It is already possible to use Y-chromosome specific STRs to exclude a suspect.