By Lisa Seachrist

Washington Editor

WASHINGTON — An independent panel of scientists convened by the National Institutes of Health (NIH) recommended that screening for cystic fibrosis carrier status be offered to all pregnant couples and those planning a pregnancy.

This is the first time that an NIH-sponsored consensus panel has recommended wide-scale genetic testing to identify healthy carriers of a mutation and is in marked contrast to the opinion of a similar panel convened five years ago when the genetic test for cystic fibrosis (CF) mutations first became available. The recommendation may pave the way for future genetic tests.

"Things have changed since the test first became available — it is more likely to identify a CF mutation," said R. Rodney Howell, panel chair and chairman of pediatrics at the University of Miami, noting that new technological developments in genetic testing have made this possible.

The panel, however, did not advocate widespread screening of newborns to diagnose CF, noting that no current research shows a benefit to such widespread testing for a relatively rare disease. The panel did recommend that screening also be made available to the family members of cystic fibrosis patients; however, it was adamant in its assertion that people being tested be protected from all types of discrimination.

"The significance of this type of screening will provide the basis for some of the complex genetic testing issues that undoubtedly will arise with other inherited diseases," Howell said.

CF is a recessive genetic disease that affects the lungs, pancreas and digestive systems. CF results when a person inherits two defective copies of a gene involved in chloride transport across cell membranes. More than 25,000 Americans have CF and approximately 850 children are born with the disease each year.

Patients with CF have symptoms ranging from mild to severe. The disease is, however, considered fatal. Advancements in treating CF, including aggressive respiratory and drug therapy as well as treatment with inhaled Dnase, have resulted in increasing average life expectancy from 18 years in 1976 to 30.1 years in 1995. But, as Howell pointed out, "there is still no cure."

Caucasians of Northern European descent are the most likely to carry a CF mutation. However, there are over 600 mutations in the CF gene. One out of every 29 Caucasians and Ashkenazic Jews in the U.S. carries a mutations for the gene and one out of every 46 Hispanics carries a mutation. Asian-Americans have a one-in-90 chance of carrying a mutation.

The panel recommended that all pregnant couples and those planning a pregnancy be tested to determine their risk for having a child with CF. Should both partners carry the mutation, they have a one in four chance of having a child with CF.

"The test will allow people to make reproductive decisions," said panel member James Evans, clinical associate professor of internal medicine at the University of North Carolina, Chapel Hill. "There is already an active interest among the prenatal population for CF screening."

The panel considered several studies which showed that when offered carrier screening, 50 to 78 percent of pregnant couples decided to be tested for carrier status. Many of those who declined testing did so because they intended to follow through with the pregnancy regardless of the result.

"Ideally, testing should be done before a couple becomes pregnant," said Stephanie Smith, director of medical genetics at the University of Mississippi Medical Center, in Jackson. "But this definitely should be done as early as possible in a pregnancy so that people can make choices."

The specter of aborting fetuses that will suffer CF has raised concerns about how people with CF will be viewed by society. The panel recognized those concerns and pointed to the fact that studies of patients with CF indicated that they did not oppose testing for the disease, even though there is yet no cure.

"It is not a goal of this consensus conference to reduce the number of people with CF," Evans said.

The panel also noted that such a screening program will require extensive education of not only the medical community, but the public as well. The primary care physicians and obstetricians who are going to be offering the test will need to be informed about the benefits and risks associated with the test. They will also need to obtain appropriate informed consent from their patients.

"It will be very important that the physicians adequately inform patients about the test and get appropriate informed consent from their patients," Howell said.

Screening for CF carrier status costs approximately $100 to $150 dollars for the test and another $200 to $300 for genetic counseling services.

Frances Collins, director of the National Human Genome Research Institute, congratulated the panel on "the thoughtful way in which they approached the issues." *