Blood cells yield cystic fibrosis clues.

Blood cells yield cystic fibrosis clues

Scientists have discovered the molecular defect thought to cause cystic fibrosis in white blood cells, a finding that may provide a laboratory model for studying this lethal genetic disease and lead to a screening test for genetic carriers.

Researchers believe patients with cystic fibrosis have a faulty chloride channel, a gate in the cell membrane that regulates the entry of chloride. Previous work has shown that epithelial cells lining the body's airways contain the malfunctioning channel, but these cells are difficult to obtain and culture, a problem that has stymied research.

Jennifer H. Chen, Howard Schulman and Phyllis Gardner of Stanford University report in the Feb. 3 SCIENCE that they have found the defective chloride channel in white blood cells taken from cystic fibrosis patients. The work, if verified, would give scientists an easier way to study the channel because white blood cells can be obtained by drawing blood and are easily cultured.

The researchers say their work may lead to a simple blood test for carriers of the cystic fibrosis gene. At present, people with a family history of the disease can undergo DNA analyses and counseling to get an idea of their risk of having a child with cystic fibrosis. One out of every 20 people in the United States carries the gene without showing symptoms. Cystic fibrosis patients inherit a defective gene from each parent.

People with the disease have abnormally thick secretions in the lungs and other organs. Researchers suspect the faulty chloride channel leads to the heavy mucus that blocks airway passages and organs, eventually causing death. The average life expectancy for a child born with cystic fibrosis is 25, although advances in treatment have kept some patients alive much longer.