Human genomic DNA quantitation system, H-Quant: development and validation for use in forensic casework.

The human DNA quantification (H-Quant) system, developed for use in human identification, enables quantitation of human genomic DNA in biological samples. The assay is based on real-time amplification of AluYb8 insertions in hominoid primates. The relatively high copy number of subfamily-specific Alu repeats in the human genome enables quantification of very small amounts of human DNA. The oligonucleotide primers present in H-Quant are specific for human DNA and closely related great apes. During the real-time PCR, the SYBR Green I dye binds to the DNA that is synthesized by the human-specific AluYb8 oligonucleotide primers. The fluorescence of the bound SYBR Green I dye is measured at the end of each PCR cycle. The cycle at which the fluorescence crosses the chosen threshold correlates to the quantity of amplifiable DNA in that sample. The minimal sensitivity of the H-Quant system is 7.6 pg/microL of human DNA. The amplicon generated in the H-Quant assay is 216 bp, which is within the same range of the common amplifiable short tandem repeat (STR) amplicons. This size amplicon enables quantitation of amplifiable DNA as opposed to a quantitation of degraded or nonamplifiable DNA of smaller sizes. Development and validation studies were performed on the 7500 real-time PCR system following the Quality Assurance Standards for Forensic DNA Testing Laboratories.

Y-chromosome STR system, Y-PLEX 12, for forensic casework: development and validation.

The Y-PLEX 12 system, developed for use in human identification, enables simultaneous amplification of eleven polymorphic short tandem repeat (STR) loci, namely DYS392, DYS390, DYS385 a/b, DYS393, DYS389I, DYS391, DYS389II, DYS 19, DYS439 and DYS438, residing on the Y chromosome and Amelogenin. Amelogenin provides results for gender identification and serves as internal control for PCR. The validation studies were performed according to the DNA Advisory Board's (DAB) Quality Assurance Standards. The minimal sensitivity of the Y-PLEX 12 system was 0.1 ng of male DNA. The mean stutter values ranged between 3.76-15.72%. A full male profile was observed in mixture samples containing 0.5 ng of male DNA and up to 400 ng of female DNA. Amelogenin did not adversely affect the amplification of Y-STRs in mixture samples containing male and female DNA. The primers for the Y-STR loci present in Y-PLEX 12 are specific for human DNA and some higher primates. None of the primate samples tested provided a complete profile at all 11 Y-STR loci amplified with the Y-PLEX 12 system. Y-PLEX 12 is a sensitive, valid, reliable, and robust multiplex system for forensic analysis, and it can be used in human forensic and male lineage identification cases.

Utility of the Y-STR typing systems Y-PLEX 6 and Y-PLEX 5 in forensic casework and 11 Y-STR haplotype database for three major population groups in the United States.

The Y-PLEX 6 and Y-PLEX 5 systems enable analysis for 11 Y-STR loci. We present here the utility of these systems in forensic casework. A total of 188 samples, including 127 evidence samples, were analyzed using either or both of the systems. The evidence sample types included fingernail scrapings, sperm or seminal fluid, epithelial cells, blood and other tissues. The Y-STR typing systems provided useful probative results in difficult cases. A reference database for Caucasian (n = 517), African American (n = 535), and Hispanic (n = 245) population groups within the United States was generated for estimating the haplotype frequency in forensic casework. Among the individuals profiled, 311 Caucasians, 412 African Americans, and 194 Hispanics provided unique profiles in their respective population datasets. This is the first report describing the haplotype database for the set of 11 Y-STR loci recommended by the Scientific Working Group on DNA Analysis Methods (SWGDAM). Linkage analysis reveals that the frequencies from forensically important autosomal loci can be multiplied with the Y-STR haplotype frequency. The results from Y-PLEX systems have been accepted in courts in the United States.

DNA profiling of azoospermic semen samples from vasectomized males by using Y-PLEX 6 amplification kit.

Post-vasectomized azoospermic semen samples (N = 6) were analyzed for short tandem repeats (STR) on the Y-chromosome by using Y-PLEX 6 and the 310 Genetic Analyzer. We have observed a wide variation in the yield of extracted DNA from 12.5-1,000 ng. This variation was attributed to the number of epithelial and/or white blood cells that are present in these azoospermic samples. DNA profiles of these vasectomized males were obtained for all six Y-STR loci, namely DYS393, DYS 19, DYS389II, DYS390, DYS391, and DYS385 amplified by using the Y-PLEX 6.