This study assessed the utility of DNA polymorphism typing of urine stains in forensic investigations.
The forensic investigation of human urine stains is important when attempting to determine the location of a crime and the manner of death. The current study collected urine and oral mucous membrane samples from 20 volunteers (10 males and 10 females). Some of the urine samples were soaked onto pieces of bleached cotton cloth in order to create urinary stains with a volume of 50, 100, 200, and 1,000 ml. Urinary DNA typing was independently confirmed by contrasting the profiles obtained from urine with those obtained from oral DNA typing. This report describes in detail the DNA extraction from urine samples, DNA extraction from urine stains and oral mucous membrane, the amplification and electrophoresis of DNA, the estimation of the amplifiable amount of urine, and the DNA typing of urine stains. The amplifiable amount of DNA was estimated by using a DNA purification kit following dialfiltration. DNA obtained from both urine and urine stains was amplified with the AmpflSTR Profiler PCR Amplification Kit and was analyzed by capillary electrophoresis using the Genetic analyzer. The amount of male and female urine necessary for obtaining a complete DNA profile was 0.2 ml and 0.08 ml, respectively. When 0.2 ml of male urine was used to create urine stains, complete DNA profiles could be obtained from just some of the stains; however, when only 0.1 ml of female urine was used, complete profiles could be obtained from all of the stains. DNA on bleached cotton remained amplifiable for 3-6 weeks. The authors recommend using a DNA purification kit following dialfiltration for the genotyping of urine stains. 3 figures, 3 tables, and 13 references