Usefulness of deoxyribonuclease I (DNase I) polymorphism for individualization from small aged urine stains.

We devised a procedure that combines a simple extraction method, isoelectric focusing and activity staining using the dried agarose film overlay method, for deoxyribonuclease I (DNase I) typing from aged urine stains. DNase I types were determined without difficulty from urine stains kept at room temperature for 3 months or more in all of the samples tested. The amounts of urine stains required for typing after 3 months of storage were estimated to be equivalent to 60-120 microl of liquid urine. Therefore, considering that useful PCR-based DNA typing has not yet been developed for urine stains, DNase I polymorphism could be considered the first biochemical marker found to be well suited for individualization from small aged urine stains.