New Light on Pre-Eclampsia Cause

Hypertension during pregnancy may be caused by lack of enzyme to regulate blood pressure

(RxWiki News) The cause of one of the most common pregnancy complications - pre-eclampsia - is still a mystery to researchers, but new research has identified another piece of the puzzle.

A new study reveals that women who get pre-eclampsia may lack an enzyme called corin. The discovery may aid future diagnosis and treatment.

"Attend all prenatal appointments with your OB/GYN."

Pre-eclampsia is a potentially dangerous condition in which a pregnant woman retains fluid and experiences high blood pressure. The only currently known treatment is delivery of the baby.

About 10 percent of all pregnancies involve pre-eclampsia, and it is a major cause of death for mothers and their babies in the developing world.

Dr. Qingyu Wu, M.D., Ph.D., of the Department of Molecular Cardiology in the Lerner Research Institute at Cleveland Clinic, led a study that looked for corin first in mice and then in women.

Corin is an enzyme normally found in the heart that helps regulate blood pressure and a woman's sodium levels. The researchers found corin in the uteruses of women and mice and decided to test what happened when it was removed from the mice.

While mice bred without corin anywhere except their hearts were fine while not pregnant, researchers saw the blood pressure begin rising in the pregnant corin-lacking mice after 17 days of pregnancy. These mice's blood pressure only returned to normal after delivery.

In the normal mice, the researchers found corin in the placenta as well as the umbilical cord, so they conducted additional experiments with the mice and determined that high blood pressure occurred when female mice had a genetic mutation that led to a lack of corin in the reproductive organs.

The corin-lacking mice also had protein in their urine, another symptom of pre-eclampsia in human women.

When the researchers then studied the women, they found evidence that the women with pre-eclampsia had low levels of corin in their uterus and that the corin they did find there came from the heart instead of the uterus.

When they studied these women's genetic code, they found two genetic mutations which appeared to relate to the low production of corin.

Because of the many changes a body experiences during pregnancy, including a larger amount of blood in a woman's body and the need to provide adequate blood to the baby, it can be difficult for the body to regulate blood pressure.

Normally, expanding blood vessels around and within the uterus help the body with regulating blood pressure and ensuring the baby gets enough blood.

But the arteries around the uterus in women with high blood pressure caused by pregnancy do not act appropriately to help with this regulation. It's possible that corin plays a part in this problem.

"Additional studies on corin or its related molecules may help to develop new methods to diagnose and treat pregnancy-induced hypertension," Wu said.

The study appeared online March 21 in the journal Nature. The study did not note any external funding sources beyond their institutions, and the authors declared no competing interests.

Other institutions involved in the research were the Jiangsu Institute of Hematology in the First Affiliated Hospital at Soochow University and The International Peace Maternity and Child Health Hospital at the Shanghai Jiaotong University School of Medicine, both in China.

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Review Date: 
March 29, 2012