Step away from the DNA? Circulating *RNA* in blood gives dynamic information about pregnancy, health
I read a lot of scientific papers. And while they’re all interesting, they don’t all make me snap to attention like the latest from Stanford bioengineer Stephen Quake, PhD. I even remarked to my husband that it’s rare to get the immediate sense that a discovery will significantly change clinical care.
If anyone’s going to shake up the status quo, however, it would be Quake. You may remember that Quake has made waves before with his pioneering discoveries involving the analysis of tiny bits of DNA circulating in our blood. His 2008 discovery that it’s possible to non-invasively detect fetal chromosomal abnormalities with a maternal blood sample has revolutionized prenatal care in this country. It’s estimated that, in 2013, hundreds of thousands of pregnant women used a version of this test to learn more about the health of their fetuses. And, in 2012, Quake showed its possible to sequence an entire fetal genome from a maternal blood sample.
Now he and his lab have gone one step further by turning their attention to another genetic material in the blood, RNA. Although information conveyed in the form of DNA sequences is mostly static (the nucleotide sequence of genes, for example), RNA levels and messages change markedly among tissues over time and at various developmental points. The difference in available information is somewhat like comparing a still photo with a high-resolution video when it comes to sussing out what the body is actually doing at any point in time.
The study was published today in the Proceedings of the National Academy of Sciences. As I explain in my release:
In the new study, the researchers used a technique previously developed in Quake’s lab to identify which circulating RNA molecules in a pregnant woman were likely to have come from her fetus, and which were from her own organs. They found they were able to trace the development of specific tissues, including the fetal brain and liver, as well as the placenta, during the three trimesters of pregnancy simply by analyzing blood samples from the pregnant women over time.
Quake and his colleagues believe the technique could also be broadly useful as a diagnostic tool by detecting distress signals from diseased organs, perhaps even before any clinical symptoms are apparent. In particular, they found they could detect elevated levels of neuronal-specific RNA messages in people with Alzheimer’s disease as compared with the healthy participants.
Quake and the lead authors, graduate students Winston Koh and Wenying Pan, liken their technique to a “molecular stethoscope.” They believe it could be broadly useful in the clinic. More from my release:
“We’ve moved beyond just detecting gene sequences to really analyzing and understanding patterns of gene activity,” said Quake. “Knowing the DNA sequence of a gene in the blood has been shown to be useful in a few specific cases, like cancer, pregnancy and organ transplantation. Analyzing the RNA enables a much broader perspective of what’s going on in the body at any particular time.”