Study: This Gene Mutation Is Linked to Extreme Morning Sickness

There’s your run-of-the-mill morning sickness during pregnancy, and then there’s hyperemesis gravidarum. The latter—an extreme, persistent nausea and vomiting—is rare, affecting only about 2 percent of pregnancies. And it’s severe: It can lead to weight loss, land you in the hospital with dehydration and even affect baby’s development. Anyone who has experienced hyperemesis gravidarum (like Kate Middleton) knows it’s the real deal, and studies are working to pinpoint the cause in order to emphasize it’s a physical, not a psychological, condition. Now one study is finding it may be linked to a gene mutation.

The study was conducted by the Keck School of Medicine of USC and Hyperemesis Education and Research (HER) Foundation, and it builds on previous research. The study’s findings were published in BJOG: An International Journal of Obstetrics and Gynaecology in February 2022. For the study, researchers looked at genes in 926 women who suffered from HG and compared them to 660 women who had normal morning sickness during pregnancy.

The study found differences in only one gene between the two groups, and it was for the gene that codes GDF15. GDF15 is a cellular stress hormone that is found in high levels in the placenta. It’s responsible for sending signals to the part of the brain that controls nausea and appetite. The researchers believe that, for women with HG, there are abnormalities in how GDF15 is sending signals to the brain.

The researchers hope their findings will help not only diagnose HG in a more timely manner, perhaps through genetic testing, but also help build more effective treatments that target the underlying cause. “For generations, it’s been thought that HG was either psychological in nature or caused by the hCG pregnancy hormone, so this breakthrough leads us in a new direction,” Marlena Fejzo, PhD, a faculty researcher at the Keck School of Medicine and the paper’s lead author, said in a press release. “Our study provides compelling evidence that abnormalities in the GDF15 gene and the protein it codes for are the main cause of HG.”

These findings are consistent with a 2018 study conducted by Fejzo, who has a personal reason for conducting this research. In 1999, she suffered a pregnancy loss due to complications from hyperemesis gravidarum. Fejzo, who initially researched cancer genetics, hypothesized genes could play a role in morning sickness as well. For the initial study, she persuaded genetic testing company 23andMe to incorporate questions about pregnancy sickness into its surveys. Fejzo and her team compared the genomes of 1,306 women who said they received IVs for their nausea and vomiting during pregnancy to the genomes of 15,756 pregnant women who didn’t experience nausea or vomiting. The most significant difference between the two groups? The first had the gene for GDF15. (In a second, unrelated study conducted around the same time, Stephen O’Rahilly of the University of Cambridge found that women who reported vomiting during their second trimester had more GDF15 in their blood at 12 to 18 weeks than those who didn’t.)

For the new study, researchers were able to pinpoint two variations of the GDF15 gene that strongly correlated to HG. The new study also looked at a more diverse participant pool and found race didn’t play a strong role in the results. Next, the researchers hope to find ways the correlation between GDF15 and HG may help improve diagnosis, as well as treatment options, including possibly developing medications that “block the GDF15 signaling pathway.”

“This condition can be very debilitating and without knowing its cause, we haven’t had specialized medications to offer patients,” Patrick M. Mullin, MD, MPH, an associate professor of clinical obstetrics and gynecology at the Keck School of Medicine and a coauthor of the study, said. “Our hope is that understanding the genetic basis of HG will support the development of more targeted approaches to treatment.”

Please note: The Bump and the materials and information it contains are not intended to, and do not constitute, medical or other health advice or diagnosis and should not be used as such. You should always consult with a qualified physician or health professional about your specific circumstances.