American Association for Clinical Chemistry
Better health through laboratory medicine
December 2007 Mentor Q&A Session: Dennis Lo
Welcome to SYCL's Mentor of the Month.  Questions and Answers will be displayed below...

Dear Dr. Lo- Your discovery of cell free fetal DNA in maternal serum is fascinating. Could you please elaborate on the events and ideas that brought you to do this wonderful discovery? Thank you.
Rochester, MN

Y.M. Dennis Lo
Prior to the discovery in 1997, I was working on the detection of fetal cells in maternal blood for 8 years. However, work in that area was not progressing well because of the extreme rarity of fetal cells in maternal blood. Thus, it was clear that a new approach was needed. In late 1996, two papers appeared in Nature Medicine reporting the detection of tumor-derived microsatellite alterations in the plasma/serum of cancer patients. As there were a number of interesting similarities between a cancer and the placenta, my team then explored the possible presence of an analogous phenomenon in pregnancy. We were lucky and found that our guess was correct, thus leading to the discovery of this previously unknown phenomenon.

Dear Dr. Lo-- What do you think about the ability to test various types of cancers (e.g. colorectal) using fecal DNA markers?
Kansas City, MO

Y.M. Dennis Lo
I find this a very direct and interesting idea. I remember reading the first publication on the detection of colorectal cancer DNA in stools by David Sidransky and colleagues in Science in 2002, when I was still a postgraduate student at Oxford. You mention “various types of cancer” in your question. I think that the fecal DNA approach is likely to be only useful for gastrointestinal cancers. For gastrointestinal cancers, the fecal DNA approach may have synergy with the alternative approach of detecting tumor-derived DNA/RNA in plasma. I would imagine that it would be easier to obtain quantitative data using the plasma approach than with fecal DNA.

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