News Release 

Fetal genome involved in triggering premature birth

Study of more than 600 infant genomes points to pathway regulating neuron growth and inflammation

PLOS

Mutations in the gene that codes for SLIT2, a protein expressed in fetal cells in placentas and involved in directing the growth of the fetal nervous system, may contribute to premature births, possibly by activating the mother's immune system. Mika Rämet of the University of Oulu and colleagues report these findings in a new study published 13th June in PLOS Genetics.

More than 10 percent of babies worldwide are born prematurely, which is the leading cause of newborn death and a source of lifelong complications. Preterm birth can run in families, suggesting that there are underlying genetic factors in the mother and the fetus that contribute to the problem. To identify the fetal genetic factors, Rämet and his colleagues performed a genome-wide association study on a Finnish population that included 247 premature infants born before 36 weeks and 419 babies carried to term. The analysis pinpointed a variation in gene for a protein called SLIT2 that helps guide the growth of neurons during development and binds to a receptor protein called ROBO1. Using placentas, which are partly fetal tissue, the researchers showed that SLIT2 and ROBO1 were expressed at higher levels in placentas from premature babies, compared to placentas from babies that were carried to term. Furthermore, in experiments using cell cultures of placental tissue, the researchers found that ROBO1 plays a role in regulating several pregnancy-associated genes related to infection, inflammation and immune response.

The researchers propose that SLIT2 and its receptor, ROBO1, are part of the signalling network that causes spontaneous preterm birth, potentially by triggering inflammation and activating the maternal immune system. The findings dovetail with previous findings that the SLIT2-ROBO1 signalling pathway is associated with multiple pregnancy complications, including preeclampsia and ectopic pregnancy. Author Mika Rämet stated that "our results are important as more detailed understanding about the fetal - as well as maternal - determinants triggering preterm birth will help us to identify those who are at the highest risk. This will allow targeted therapeutic interventions." In the future, the researchers hope to validate these findings using a larger population. Such an analysis might also identify additional genetic factors that contribute to early birth.

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Peer-reviewed / Observational study / People

In your coverage please use this URL to provide access to the freely available article in PLOS Genetics: http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1008107

Citation: Tiensuu H, Haapalainen AM, Karjalainen MK, Pasanen A, Huusko JM, Marttila R, et al. (2019) Risk of spontaneous preterm birth and fetal growth associates with fetal SLIT2. PLoS Genet 15(6): e1008107. https://doi.org/10.1371/journal.pgen.1008107

Funding: This work was supported by the Jane and Aatos Erkko Foundation (MH and MR), Sigrid Jusélius Foundation (MH) and Competitive State Research Financing of the Expert Responsibility Area of Oulu University Hospital (MR), March of Dimes Prematurity Research Center Ohio Collaborative, March of Dimes, URL:http://www.marchofdimes.org/, the Bill and Melinda Gates Foundation, URL:http://www.gatesfoundation.org (OPP1113966, LJM) and NIH/The Eunice Kennedy Shriver National Institute of Child Health and Human Development, URL:https://www.nichd.nih.gov/ (HD091527, LJM). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests: No authors have competing interests.

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