|Physicians Recommend Gene Test for Families with Hypertension|
By Cheryl Simon Silver
Posted: July 23, 2004
The American College of Chest Physicians this month issued new guidelines advising individuals who have a family history of pulmonary arterial hypertension (PAH) to seek genetic testing. The test screens for a specific gene mutation that is associated with an increased risk for the disease.
About 50 percent of individuals with familial PAH possess a mutation in a gene known as BMPR2. Approximately half of children or siblings of individuals with the familial form of PAH also have the gene mutation. Not all carriers of the mutation develop the disease, but once carriers are identified they can be closely monitored so that treatment can begin when the first signs and symptoms of disease occur.
“We know that you may have the gene and still not have the disease,” says Lewis J. Rubin of the University of California San Diego School of Medicine in La Jolla. “But the knowledge that you have the gene may mean that the disease will be identified sooner and we can address it aggressively, hopefully slowing the progression of the disease.”
While the familial form of PAH is life threatening and remains a serious condition, Rubin notes that “new treatments are emerging that may prolong survival.”
Rubin chaired the panel of international scientists that issued the guidelines, which are based on evaluation of all published research related to PAH.
The genetic test is not widely available, but it can be obtained at several centers that specialize in the genetics of PAH. Rubin stresses that genetic counseling is an important companion to the genetic test.
If children and siblings of PAH patients do not have the gene mutation, their chances of developing PAH are the same as the rest of the population. In the United States, there are more than 100,000 cases of PAH, with several thousand new cases diagnosed each year.
Another key recommendation in the report is that physicians refrain from routinely prescribing calcium channel blockers as the first line treatment for PAH because the drugs are helpful for only a small subset of patients.
“This is a very important message for the treatment community,” Rubin says. “The evidence supporting their widespread use is nonexistent.” He says that patients should undergo a test that measures whether there is dynamic constriction of the blood vessels in the lungs. If they do not have this kind of constriction, calcium channel blockers can have life-threatening side effects, and other medications to alleviate the symptoms should be prescribed instead.
Pulmonary hypertension occurs when the arteries that supply blood to the lungs become narrowed. Blood flow to the lungs decreases, and high blood pressure can develop in the lung arteries. The condition is difficult to diagnose in its early stages, when treatment can have the greatest impact. PAH occurs in individuals of all ages, with the highest incidence among women ages 20 to 40.
The guidelines are published in the July issue of CHEST.