Y-STR Profiling of Semen Stain Evidences of Azoospermic Individuals

Background: Nowadays, STR polymorphism is the method of choice in all governmental and private laboratories working in DNA profiling, since it allows DNA investigators to analyze all types of biological evidences, besides obtaining high discrimination power for a large number of cases including both criminal identification and paternity tests as well. Azoospermia
is a condition that when occurs in certain individual it causes a complete absence of the major DNA source in semen which is spermatozoa leading to infertility. The aim of this study is to obtain STR profiles from those minute DNA
quantities that might be present in the semen stain evidences of Azoospermic individuals, to generate confidential results presented to the court after the analysis of these special type of biological evidences. 
Methods: 100 semen stain trace samples divided into two groups (test & control samples) were recovered by a simulating manner to that which is done in the crime scene investigation, then DNA was extracted using QIAamp DNA Micro Kit, with special modifications in the extracting procedure applied for the Azoospermic test samples to concentrate and obtain minute quantities of DNA. DNA quantification was done using a Real-time PCR utilizing Quantifiler Duo Kit. PCR was done using an AmpFlSTR Y-Filer Kit, then amplified products for all test and control samples were typed using a 3130 Genetic Analyzer.
Results: Full Y-STR profiles were obtained from semen stain evidences attributed to Azoospermic individuals, with a percentage reaches 100%.
Conclusion: The methodology followed in this research should be applied in case of performing DNA typing for semen stain evidences recovered from crime scenes, to guarantee obtaining full DNA profiles even with Azoospermic samples.