Most women experience some morning sickness during pregnancy, but the pregnant women who experience the more severe form of nausea and vomiting, known as hyperemesis gravidarum. New research finds two specific genes associated with this condition 

In hyperemesis gravidarum, the symptoms are so serious that hospitalization is required. The same condition has happened to Kate Middleton, the Duchess of Cambridge, during her pregnancies.

A new study led by researchers at UCLA and published in the journal Nature Communications has identified two genes associated with hyperemesis gravidarum, whose cause has not been determined in previous studies. 

The genes, known as GDF15 and IGFBP7, are both involved in the development of the placenta and play essential roles in early pregnancy and appetite regulation.

Marlena Fejzo et al. said, "It has long been assumed that the pregnancy hormones, human chorionic gonadotropin or estrogen, were the likely culprits of extreme nausea and vomiting, but our study found no evidence to support this."

The two genes, she added, coincidentally are linked to cachexia, a weight loss and muscle wasting condition that leads to death in about 20 percent of cancer patients and has similar symptoms to hyperemesis gravidarum.

Fejzo herself had hyperemesis gravidarum and lost a pregnancy to the condition in 1999. The debilitating symptoms can include rapid weight loss, malnutrition, and dehydration due to persistent nausea and vomiting.

Current medications to treat the condition are mostly ineffective and can lead to serious health consequences for both mother and baby. The state is the second leading cause of hospitalization during pregnancy. Women often require intravenous fluids and, in the most severe cases, feeding tubes.

Previous research has shown that severe nausea and vomiting during pregnancy often runs in families, suggesting that genetics plays a role. For this study, the team compared the variation in DNA from pregnant women with no nausea and vomiting to those with hyperemesis gravidarum to see what the differences were between the two groups. 

DNA variation around the genes GDF15 and IGFBP7 was associated with hyperemesis gravidarum. The findings were then confirmed in an independent study of women with hyperemesis gravidarum.

In a separate follow-up study, researchers then proved the proteins GDF15 and IGFBP7 are abnormally high in women with hyperemesis gravidarum. They presented these findings at the International Colloquium on Hyperemesis Gravidarum in 2017.

The next step is to determine whether GDF15 and IGFBP7 protein levels could be altered safely in pregnancy to minimize nausea and vomiting. "I hope that one day a medication that affects this pathway will be used to treat and possibly cure hyperemesis gravidarum successfully," Fejzo said.