Dennis Lo bets on blood to bare all, with tests that saved 10 million mums from the needle

Yahoo

22-02-2025

In the first instalment of a series to mark the 10th anniversary of the Future Science Prize, Holly Chik and Shen Xinmei look at Professor Dennis Lo's groundbreaking discovery of fetal DNA in maternal plasma, which earned him the inaugural award in the Life Sciences category in 2016.
The blood tests of the future can reveal a lot more about a person's health, from neurodegenerative conditions to age-related diseases, said the Hong Kong clinical pathologist whose pioneering work in 1995 spared 10 million expecting mothers worldwide from the amniocentesis needle.
"In neurodegenerative diseases like Alzheimer's, I [can] use circular nucleic acids to diagnose those conditions", said Professor Dennis Lo Yuk-ming during an interview last month with the Post. "Ageing changes the formatting of DNA, so [one] can use epigenetics as a clock of the DNA."
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Professor Dennis Lo Yuk-Ming in his laboratory at the Centre for Novstics at the Hong Kong Science and Technology Park on 21 June 2023. Photo: Yik Yeung-man
The T21 test, available for between HK$4,500 (US$578) and HK$8,000 at various hospitals and clinics in Hong Kong, has been rolled out to women in 90 countries since 2011.
For his work, Lo received the inaugural Future Science Prize for life science in 2016, and was named the Thomson Reuters Citation Laureate the same year, considered an index of the most promising Nobel Prize winners. Six years later, he received the Laskey-DeBakey Clinical Medical Research Award, a top US biomedical research prize.
The Chinese University of Hong Kong's president, Professor Dennis Lo Yuk-ming, with the painting that inspired his discovery of genetic markers in human blood, at his office in the Hong Kong Science & Technology Park on 7 January 2025. Photo: Jonathan Wong.
Inspired by a painting that depicted railway signals, Lo made more discoveries of what he called markers through the genetic material in the human blood, including circular nucleic acids, or molecules that carry genetic information in closed-loop structures.
The discovery widened the possible applications, including a blood test to identify areas of the brain that are contributing to neurological issues. That would save the person from undergoing an MRI scan, saving time and money, he said.
Blood tests in epigenetics, or the study of chemical reactions that influence the way genes work, can also be used to measure ageing in human organs, he said. "Is one or more of the organs ageing faster than others?" he said. "If that is the case, can we do something to slow that down?"
Extracting DNA from a woman's amniotic fluid for genome sequencing during the "CUHK Pioneers Whole Genome Sequencing for Prenatal Diagnosis in Hong Kong" at the Prince of Wales Hospital in Sha Tin on 17 September 2019. Photo: David Wong.
"Breakthroughs usually come up if you can see the hidden link between apparently unrelated subjects", Lo said in looking back at his career. "In my story, it was pregnancy, linked to transplant and to cancer."
As a medical student at The University of Oxford in the late 1980s, Lo aspired to develop a new technique to replace amniocentesis, an invasive and risky procedure of inserting a needle into the uterus to obtain fetal DNA.
He thought long and hard about the "possibility that the fetus might release cells into the mother's bloodstream, but that thinking at the time was not [in the] mainstream because we knew that the fetal blood circulation system is separate from the mother's", he said. "Theoretically, what I was proposing was not very feasible."
A blood test for health screenings during a health exhibition on common respiratory diseases organised by Chinese University of Hong Kong's Medical Society at Sunshine City in Ma On Shan on 5 October 2024. Photo: Edmond So
He persisted, launching his research after studying about polymerase chain reaction (PCR), a technique for amplify DNA molecules and making millions of their copies, from the geneticist John Bell, who later served as the Chair of Medicine at Oxford.
Lo sought out to find Y chromosomes, the male-determining gene, in a pregnant woman's blood. Still, the number of fetal cells that entered the maternal bloodstream was very small, not enough to be usable as a robust test.
After eight years of work, Lo returned to Hong Kong in 1997 in search of a change of direction. He decided to switch his focus to blood plasma, the light-yellowish liquid that carries the platelets, the red blood cells and white blood cells.
Blood plasma being prepared at a blood bank in Zhenjiang city in eastern China's Jiangsu province on August 2, 2014. Photo: Xinhua.
Even then, the conventional wisdom was that DNA did not float outside cells. As he gazed into a boiling pot of instant noodles one night, Lo had his eureka moment.
"I arrived at something really simple: take some plasma, boil it for five minutes and test a few drops of that boiled soup with PCR", he said, noting that DNA is robust enough to withstand heat. "Lo and behold, the signal occurred, much stronger than if you used the cells. In plasma, there are enzymes which might degrade the DNA. So if you heat that, you kill those enzymes, leaving the DNA behind."
After the T21 blood test came into clinical use, Lo shifted his search to male cells in women, and organ transplants came to mind.
Professor Dennis Lo Yuk-ming with a RNA microchip, used to detect RNA molecules located on chromosome 21, at the Postgraduate Education Centre of the Faculty of Medicine at the Prince of Wales Hospital in Sha Tin on 9 January, 2007. Photo: SCMP
His studies showed that Y chromosomes could be detected in the blood of women who received men's transplanted kidney or liver, a discovery that led to the development of tools for detecting transplant rejections.
"If the body rejects an organ, more cells are killed, [so] when the cells die, they release the DNA into the bloodstream", he said. "If you successfully treat that, the [detected DNA] level would come down."
Blood tests can also be used to detect cancer, because pregnancies and tumours are both "invasive" in essence to the host body.
"A baby growing inside a mother is a little bit invasive to the placenta, just like a cancer growing in a patient", he said.
While Down syndrome occurs because of an extra copy of the 21st chromosome pair, gene amplification is common in cancer cells, where certain genes that are advantageous to the growth of cancer produce more copies. These genes are detectable in a similar way to chromosome 21.
(Left to Right) Allen Chan Kwan-chee, Professor of Chemical Pathology at CU Medicine; Professor Dennis Lo Yuk-Ming, Director of the Li Ka Shing Institute of Health Sciences at Chinese University of Hong Kong (CUHK); and Dr. Jacky Lam Wai-kei, Assistant Dean (Research), Assistant Professor, Department of Chemical Pathology at CU Medicine, during a press conference on a CUHK study about the early detection of nasopharyngeal cancer on 11 July 2023. Photo: May Tse
Lo and his team developed a blood test for detecting cancers, starting with nasopharyngeal carcinoma, a type of cancer in the throat from the back of the nose to the back of the mouth, which is more prevalent in southern China than Western countries.
The future does not end there. The blood-brain barrier, the semi-permeable membrane between the blood and the interstitium of the brain, holds great potential for exploration.
Future blood tests could incorporate DNA reading into their current roles of evaluating organ function and helping diagnose diseases, Lo said.
"In the future, a blood test would also involve this type of technology", he said. "Apart from our usual liver function tests, they may also read out DNA signs."
"Blood plasma carries DNA released by different parts of a body. We can decipher the mixture back into their various sources", he said. "If there are injuries to organs, the representation from that part [of the body] would increase," making it possible to decipher the histories of strokes or heart attacks from blood, he said.
Asked about the global health impact he would like his research to have, Lo said "our goal is to maintain our health for as long as possible and to make it accessible to as many people as we can."
This article originally appeared in the South China Morning Post (SCMP), the most authoritative voice reporting on China and Asia for more than a century. For more SCMP stories, please explore the SCMP app or visit the SCMP's Facebook and Twitter pages. Copyright © 2025 South China Morning Post Publishers Ltd. All rights reserved.
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