UTI preventing DNA degradation of storing urinary samples for genotyping

Abstract 

In forensic practices, individual identification of urinary samples is necessary when sample switching or handling are suspected. DNA degradation with time elapsing and the low yield of extracted urinary DNA prevent its application. Storage of urine prior to analysis is increasingly advocated yet no best practice has emerged. To improve the genotyping based on storing urinary samples, we employed UTI (Urinary Trypsin Inhibitor) to prevent urinary DNA degradation. Urinary samples from 10 (5 females and 5 males) healthy volunteers from China were stored at −80°C with different concentrations (0–0.8μg/mL) of UTI. Urinary DNA was genotyped with Identifiler Kit at days of 1, 3, 5, 7, 9, 11 and 13 after storage. The average detection rate of STR loci of urinary DNA with or without UTI were statistically significant and UTI at 0.2μg/mL level is enough for urine storing. Also, significant differences in DNA yield were noted between female and male urine samples.

Keywords: Forensic genetics, Urine, Urinary Trypsin Inhibitor (UTI), Individual identification