The gene mutation that causes cystic fibrosis also appears to protect against infection with typhoid fever bacteria, a study supported by the National Institute of Allergy and Infectious Diseases (NIAID) has found. The finding could explain why an estimated 12 million people in the United States carry the gene for such a highly fatal childhood disease. Researchers led by Gerald Pier, Ph.D., of Brigham and Women's Hospital and Harvard Medical School in Boston, report the finding in the May 7, 1998, issue of the journal Nature.

"This is an interesting finding that underscores how basic research in one disease area often leads to discoveries in another area," says NIAID Director Anthony S. Fauci, M.D. "It also is a good example of how pathogenesis research - the study of how pathogens interact with the host to cause disease - creates opportunities for applied research."

Approximately 2,500 babies with cystic fibrosis are born each year in the United States. Before the 1950s, most children with the disease died by age 1 or 2. Today, with better methods for managing the disease, the average survival of these individuals is about 30 years.

"In most cases of inherited disease with high rates of childhood mortality, the defective gene does not remain in the gene pool," says Dr. Pier. "The disease and the gene causing it literally die out. When that doesn't happen, we find that it is because carriers - healthy people with one good copy and one bad copy of the disease gene - have some enhanced survival advantage." For example, Dr. Pier notes that individuals with a single copy of the sickle cell disease gene are more resistant to malaria infection than people who do not have the gene. Scientists have speculated that cystic fibrosis carriers also have enhanced protection against an infectious agent, but until now, they didn't know which one.

Background

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Contact: John Bowersox
jbowersox@nih.gov
301-402-1663
NIH/National Institute of Allergy and Infectious Diseases
6-May-1998