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The Cause of Chronic Morning Sickness

MORNING SICKNESS affects most women during pregnancy, but some pregnant women develop chronic nausea and vomiting. New work carried out at the University of California, Los Angeles (UCLA), Los Angeles, California, USA has identified two genes, GDF15 and IGFBP7, that are thought to play a key role in the progression of the condition.

Chronic nausea and vomiting, known as hyperemesis gravidarum, affects approximately 2% of pregnant women and can induce rapid weight loss, malnutrition, and dehydration, which can result in hospitalisation or even pregnancy loss. Many of the current therapies for the disorder are largely ineffective, leading the research team at UCLA to investigate the genetic roots of the disorder.

The team analysed the DNA of hyperemesis gravidarum patients and compared it with non-vomiting, non-nauseous pregnant women. The comparison results showed that the major pregnancy hormones oestrogen and human choronic gonadotropin played no role in hyperemesis gravidarum. “It has long been assumed that the pregnancy hormones, human chorionic gonadotropin or oestrogen, were the likely culprits of extreme nausea and vomiting, but our study found no evidence to support this,” explained Dr Marlena Fejzo, UCLA. The study revealed consistently marked differences in the DNA around GDF15 and IGFBP7 genes between vomiting and non-vomiting patients, leading the team to conclude that the two genes were associated with the progression of chronic morning sickness. The findings of the study have since been supported by an independent analysis of women with the condition, and, more recently, by a separate follow-up study that observed that the GDF15 and IGFBP7 proteins were elevated to abnormal levels in hyperemesis gravidarum patients.

Hyperemesis gravidarum treatments have been stalled due to lack of accurate findings in recent years. The identification of these important genes could create a plethora of new research and treatment opportunities to combat the disorder, including finding ways to safely alter the GDF15 and IGFBP7 protein levels. Dr Fejzo concluded: “It is my hope that one day a medication that affects this pathway will be used to successfully treat and possibly cure hyperemesis gravidarum.”