DNA TYPING OF URINE SAMPLES FOLLOWING SEVERAL YEARS OF STORAGE

The possibility of typing DNA polymorphisms on urine samples was inves tigated in a controlled storage experiment and for samples that were 1 -7 years old. Female urine samples showed a higher amount of epithelia l cells and therefore a higher DNA yield. Employing the polymerase cha in reaction, specific amplification results were achieved for all samp les over a 6 month storage period. The microscopical examination of th e samples revealed not only differing degrees of contamination with ba cteria, yeasts and fungi, but also the presence of still intact epithe lial cells. Only 20% of the male samples and 32% of the female samples yielded specific amplification results. By separating the human cells from the contaminating organisms prior to DNA extraction, the number of successfully typed samples could be improved to 35% of the male and 77% of the female samples. This result confirms that excess amounts o f coextracted non-human DNA can inhibit the specific amplification of human target sequences.