Testing for two genetic variants may identify women at risk for high blood pressure during pregnancy, according to a new study. Photo by Free-Photos/Pixabay
Aug. 12 (UPI) -- Two unique gene variants cause sudden-onset high blood pressure in pregnant people, a study published Thursday by the journal Nature Genetics found.
The discovery means that genetic tests could be used to screen pregnant people for these variants and identify those at risk for high blood pressure, or hypertension, the researchers said.
In the study, testing for the variants correctly identified nine of 10 women who would have developed high blood pressure during pregnancy, allowing them to begin treatment earlier, according to the researchers.
"What was particularly satisfying is that recognition of the cause of hypertension in these women enabled them to complete a successful pregnancy," study co-author Dr. Morris Brown said in a press release.
"Afterwards they were completely cured of hypertension by a procedure ... and were able to stop all their drugs," said Brown, a professor of endocrine hypertension at Queen Mary University of London in England.
About one in 12 people in the United States develop high blood pressure during pregnancy, the Centers for Disease Control and Prevention estimates.
As a result, they are at increased risk for stroke and preterm delivery, according to the agency.
People who are overweight or obese, those who smoke and those age 35 and older are at increased risk for the condition, as are those who are pregnant for the first time and who have a family history of the disorder, research suggests.
Nearly half of adults in the United States have high blood pressure and having it before pregnancy increases a person's risk during pregnancy, according to the CDC.
However, nearly one in 10 cases of high blood pressure, irrespective of pregnancy status, have a specific cause that can be identified and treated, Brown and his colleagues said.
The most common cause of high blood pressure is a tiny benign lump or growth in one of the adrenal glands, which are located near the kidneys and produce steroid hormones, the researchers said.
The hormone aldosterone stimulates the kidneys to retain salt and, hence, increases blood pressure, a condition known as primary aldosteronism that is resistant to most prescription drugs, they said.
In this new study, the Queen Mary University of London researchers found two genetic variants that cause primary aldosteronism, particularly in women with sudden-onset of high blood pressure and low blood potassium in the early months of a pregnancy.
The variants -- CTNNB1 and GNA11 -- switch on a receptor molecule in the adrenal cells that recognizes the pregnancy hormone human chorionic gonadotropin, they said.
This same hormone is measured in routine pregnancy testing and, in some people who are pregnant, it triggers a surge of aldosterone production, causing high blood pressure, according to the researchers.
Pregnant women in the study who tested positive for the two variants underwent a procedure to remove the benign growth in their adrenal glands following childbirth, Brown said.
The procedure resolved their high blood pressure and allowed them to discontinue drug treatment for the condition, he said.
People planning a pregnancy need "to be aware of the existence of this novel type of primary aldosteronism in ... puberty or early pregnancy, so that [it] can be diagnosed and appropriate treatment started," Brown told UPI in an email.
"We know of some cases where [pregnancy] terminations were performed because the physician was unable to control the blood pressure or other manifestations with conventional therapy," he said.