On targeting cell-free DNA in urine: a protocol for optimized DNA analysis.

This is not the first editorial in Clinical Chemistry dedicated to the testing of urine for cell-free DNA. In 2000 Lo(1) highlighted the findings of Botezatu et al.(2), who were the first to describe a transfer of DNA across the kidney barrier into urine. The origins of detected transrenal DNA sequences were carcinomas, blood transfusions, and, in pregnant women, the fetus. Following this first report, some pioneering work was done in transplant medicine. Urinary microchimerism was found in women after receiving kidney transplants from males(3)(4). In a quantitative analysis it was demonstrated that transplant-derived DNA was increased during graft rejection, indicating a potential marker for transplant control(4). Later, attempts were made to detect cell-free fetal DNA in maternal urine. However, maternal urine analysis was faced with technical difficulties, and it was suggested that the concentration of transrenal DNA might be too low for standard PCR protocols. …