Md. Taqi Yasir
The DNA of an unborn baby floats freely in its mother’s blood plasma, the yellow liquid that holds blood cells in suspension. That DNA is a window into an unborn baby’s health, and future. But, at the time of this discovery, the medical world wasn’t interested. In 1996 when Yuk Ming Dennis Lo made this discovery he knew would change modern medicine. According to him, “They thought that you could only use it for sex selection,” says Lo, now the Director of the Li Ka Shing Institute of Health Sciences, in Hong Kong. This was deemed by experts to be a narrow application and one filled with ethical problems.
The medical world had missed what would become one of the 21st century’s biggest breakthroughs. Yuk Ming Dennis Lo’s quest to find fetal DNA in the mother’s blood had begun at Oxford University, where he met pioneering scientist Professor John Bell. Lo said in this regard “I heard him give a lecture about the polymerase chain reaction (PCR). He said this modus operandi would change the world.”
PCR is a technique used to amplify a single piece of DNA into thousands, or even millions, of copies. Lo learnt how to use the cutting-edge technology, and soon after searched for a way to apply it. The traditional test for many mothers-to-be was to undergo a procedure called amniocentesis, where fluid is extracted from the amniotic liquid surrounding a baby in the womb. The cells within the fluid are then screened for health conditions, such as Down syndrome. Science, however, had to catch up with his ambition: During this time as a student in the 1980s, the blood of a baby and its mother were believed to be separate.
Lo began an eight-year search for fetal DNA inside a mother’s blood cells. But the number of fetal cells that enter this part of the maternal blood turned out to be very small, and the search had to be called off. In 1997, it was time for a change. Prenatal sequencing of the entire genome could, in the future, screen an unborn baby for various late onset disorders, gene defects including the breast cancer gene BRCA1 and even predict hair color or longevity. A test has already been made available to 10,000 middle-aged men in Hong Kong, and has the potential to save hundreds of thousands of adult lives around the world.
Lo has also used the “liquid biopsy” to monitor organ transplant rejection, and even the health of a patient after a car crash. If an organ, or tissue, starts to fail it releases DNA into the blood stream, which can now be picked up using this method. Lo’s next focus is on an even less invasive form of DNA testing using a mother’s urine. “After a woman conveys a baby, two hours later the fetal DNA is gone from her bloodstream. Where does it go? We thought maybe it was in the urine.” And in the urine it was, on condition that yet another transom into both mother and baby and their future health.