Years passed without Lo’s breakthrough finding any real audience or application.
“The big prize, the medical world thought, would be if you could use that for testing for Down syndrome,” Lo remembers.
Down syndrome is caused by a fetus having an extra copy of chromosome 21. Traditionally, the condition was diagnosed by looking at cells from a fetus and counting the chromosomes.
Scientists didn’t believe a diagnosis could be made using cell-free DNA (cfDNA).
But Lo proved them wrong.
After another decade of dedication, in 2007, his team showed that due to the extra copy of chromosome 21, the number of molecules produced from this chromosome are increased in the mother’s blood plasma if she is carrying a baby with Down syndrome.
“People thought we were crazy because that method meant you’d have to do several PCR tests,” says Lo.
The amount of fetal DNA in the plasma, he says, is low, so several amplifications are needed to create enough data to analyze.
The expense of this meant that wouldn’t be practical. At least not then.
Luckily for Lo, the introduction of next generation sequencing in 2008 meant millions of DNA fragments could be produced in rapid time.
In 2011, Lo launched his non-invasive prenatal blood test for Down syndrome and today, the test is available in more than 90 countries. The last time anyone counted, more than two million pregnant women had been tested.
Right from the beginning, Lo says he was “very conscious about the ethical implications.” When he licensed his technology he did so with a clause firmly in place, prohibiting its use for sex selection.
A controversial market exists in Hong Kong for prenatal gender testing as blood tests are far more conclusive in the early stages than ultrasounds. The tests cater largely to clients from mainland China where couples have a preference for sons, and where prenatal gender tests are illegal but abortions are not.
Lo soon discovered that the secrets held by just a few drops of blood are almost limitless.
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.
According to Lo, the prohibitively expensive cost means such tests are not being performed right now.
“We’ve basically created … a non-invasive window to the body.”
Seeking out cancer
Today, Lo is instead working on a blood test, for adults, that can detect liver, nose and throat cancer at stages so early they would be invisible to conventional screening methods.
Dubbed a “liquid biopsy,” it scans the blood plasma for ctDNA released by cancer cells. Lo believes it is possible to identify what type of cancer a patient has, and what stage the disease is at — all from this DNA.
Such 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.
The next treasure trove
Lo’s next focus is on an even less invasive form of DNA testing — using a mother’s urine.
“After a woman delivers 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, providing yet another window into both mother and baby — and their future health.
“That, I think, is going to be the next treasure trove.”
The Article Orignal Published By http://edition.cnn.com/2016/03/24/health/dennis-lo-dna-discovery/index.html