| The sex of an individual is one of the most important attributes when developing a physical profile for a forensic investigation. Current molecular sexing techniques work well with high quality samples; however, when analyzing challenging samples, such as ancient skeletal remains or tissue with little DNA, a more sensitive sexing method is required. To represent the standard molecular sexing technique, the single copy amelogenin gene on the X and Y chromosomes was amplified using SYBRRTM Green realtime PCR. In a comparative assay, DYZ1, a high copy repetitive element on the Y chromosome, was multiplexed with the Ya5 Alu repetitive sequence as a human and female control, and amplified using TaqManRTM technology. The sensitivity and accuracy of each method were compared by analyzing both high molecular weight and artificially degraded DNA, along with low quality DNA extracted from hair shafts and ancient skeletal remains. The DYZ1/Alu assay was successful using as little as 0.0623 pg of high molecular weight DNA, whereas the amelogenin assay required 1500 times more DNA. Further, the DYZ1/Alu assay required even less artificially degraded DNA for a positive result, the exact opposite finding using amelogenin. The DYZ1/Alu assay correctly sexed 28 of 30 hair shafts and yielded sexing results for all 41 bones, while the amelogenin assay correctly sexed 16 of 30 hair shafts and yielded sexing results for only 12 of 41 bones. Ultimately, the DYZ1/Alu assay proved to be a far more sensitive and accurate sexing technique than the standard amelogenin sexing method. |
