Transcripts circulating in the blood provide real-time information about maternal, fetal, and placental health.
by Amanda Heidt
Preeclampsia, a potentially fatal complication that affects roughly 5 percent of pregnancies worldwide, can only be diagnosed after the onset of symptoms such as high blood pressure, so treatment is always reactive. “The next really big need is better methods to diagnose or predict risk of pregnancy complications such as preeclampsia,” says Fiona Kaper, a senior director of scientific research at the biotech company Illumina.
To identify possible biomarkers of the condition, Kaper and her colleagues drew blood from 40 pregnant women with early-onset severe preeclampsia and 73 unaffected expecting mothers. Circulating in the blood of each mom-to-be is her own RNA, as well as transcripts from the placenta and the fetus. Studying these circulating RNAs (cRNAs), the team identified 30 maternal, fetal, or placental genes with altered expression patterns in women with preeclampsia compared with controls. A machine algorithm also identified 49 genes with altered expression, including 12 that overlapped with the earlier list, suspected of being linked to preeclampsia.
To test the ability of the 49 suspect genes to predict preeclampsia, the researchers classified an independent cohort of two dozen women, half with early-onset preeclampsia and half without signs of the condition. The model predicted which women had preeclampsia with 85 percent to 89 percent accuracy.
While large-scale, prospective studies are still needed, cRNA screening represents a step toward earlier preemptive diagnosis, says Kathryn Gray, an obstetrician at Brigham and Women’s Hospital who was not involved in the study. She notes that researchers have been doing something similar in detecting circulating tumor DNA for cancer screening. “It’s really exciting that we’re applying some of these . . . strategies that have been used in cancer to pregnancy. We’re always a bit behind in women’s health and pregnancy in applying the most cutting-edge technologies.”
S. Munchel et al., “Circulating transcripts in maternal blood reflect a molecular signature of early-onset preeclampsia,” Sci Transl Med, 12:eaaz0131, 2020.