Dennis Lo, also called Yuk Ming Dennis Lo, is a professor at the Chinese University of Hong Kong in Hong Kong, China. In 1997, Lo discovered fetal DNA in maternal plasma, which is the liquid component of a pregnant woman's blood. By 2002, Lo distinguished the DNA differences between pregnant women and their fetuses, enabling scientists to identify fetal DNA in pregnant women's blood. Lo used his discoveries to develop several non-invasive and prenatal genetic tests, including tests for blood group status and Trisomy 21, also called Down's Syndrome. Lo's discovery of fetal DNA in maternal plasma lessened the risks to pregnant women and fetuses during prenatal testing, and it enabled early identification of potential genetic mutations in developing fetuses.

In the late 1990s researchers Yuk Ming Dennis Lo and his colleagues isolated fetal DNA extracted from pregnant woman’s blood. The technique enabled for more efficient and less invasive diagnoses of genetic abnormalities in fetuses, such as having too many copies of chromosomes. Lo’s team published their results in 1997’s “Presence of Fetal DNA in Maternal Plasma and Serum.” The results led to developments of clinical tests that can access fetal genetic information and detect genetic abnormalities before birth without the significant risks that can potentially harm the fetus associated with invasive genetic testing techniques.

Noninvasive fetal aneuploidy detection technology allows for the detection of fetal genetic conditions, specifically having three chromosomes, a condition called aneuploidy, by analyzing a simple blood sample from the pregnant woman. Dennis Lo and Rossa Chiu researched methods of detection of aneuploidies in the early twenty-first century. Their research has been specifically applied to three trisomies, trisomy twenty-one known as Down syndrome, trisomy eighteen known as Edwards Syndrome, and trisomy thirteen known as Patau Syndrome. Prior to the ability to detect fetal DNA in a pregnant woman’s blood, physicians performed amniocentesis or chorionic villus sampling, two techniques that increase the risk of spontaneous abortion. Noninvasive detection of trisomy twenty-one, eighteen, and thirteen technology allows for a more accurate and safer detection of those conditions than methods available before.

In 2007, Dennis Lo and his colleagues used digital polymerase chain reaction or PCR to detect trisomy 21 in maternal blood, validating the method as a means to detect fetal chromosomal aneuploidies, or an abnormal number of chromosomes in a cell. The team conducted their research at the Chinese University of Hong Kong in Hong Kong, Hong Kong, and at the Boston University in Boston, Massachusetts. Because small amounts of fetal DNA appear in maternal blood during pregnancy, Lo and his team hypothesized that they could detect fetal chromosomal aneuploidy trisomy 21, or Down’s syndrome, in a sample of maternal blood. The group diagnosed Down’s syndrome in unborn fetuses by first taking a maternal blood sample, then amplifying the small amounts of fetal DNA in the maternal blood using digital PCR, and applying two genetic methods to that sample. Lo and his colleagues’ experiment demonstrated the accuracy of a novel, noninvasive method for fetal chromosomal aneuploidy testing that can enable people to make informed decisions about their pregnancies.