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Cystic Fibrosis Gene Linked to Fatty Acids

By Cheryl Simon Silver

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Cystic Fibrosis

New research suggests that the gene that causes cystic fibrosis may affect a person’s ability to metabolize ordinary fatty acids. The new information adds another piece to the complex puzzle of a devastating disease that has eluded a cure since the discovery of the cystic fibrosis (CF) gene more than a decade ago.

The recent study shows that people with the CF gene have increased levels of a fatty acid that causes inflammation and decreased levels of another that reduces inflammation. The two fatty acids in question, arachidonic acid (AA) and docosahexaenoic acid (DHA), are involved in many biological functions, including inflammation.

Scientists have long known that inflammation is an important factor in CF. Inflammation promotes production of mucous in the lungs of people with the disease, where it impairs breathing and makes it hard to fight infections. It also affects the pancreas, where the thick secretions prevent digestive enzymes from reaching the intestines to help break down and absorb food.

“There is some basic problem with the CF gene that affects the types of fat in a person’s cells,” says Brian O’Sullivan, who directs the Cystic Fibrosis Center at the University of Massachusetts Medical School in Worcester, where the study was done. He worked with Steven Freedman of Beth Israel Deaconess Medical Center in Boston and his colleagues.

They find that some CF patients have a fatty acid imbalance similar to one that Freedman discovered a few years ago in mice.

The findings, reported in the New England Journal of Medicine, suggest a possible new avenue for treatment: Doses of the fatty acid DHA. Mice with CF improved after taking large amounts of DHA, but the amount of fatty acids needed to make a dent in the disease is “enormous” relative to what a person could ingest and absorb, O’Sullivan says.

Genzyme Corporation of Cambridge, Massachusetts, which holds a license for the patent on the use of DHA in CF patients, is meeting with the researchers to explore ways to deliver more DHA to CF patients and possibly correct the imbalance.

Freedman’s finding that mice with the CF gene don’t become sick until they are weaned from their mother’s milk also suggests a fatty acid link. Human breast milk, like the milk from mice, is rich in DHA as well as other beneficial substances such as antimicrobial proteins. O’Sullivan has conducted a survey of mothers whose children are treated in cystic fibrosis clinics. He says there are “tantalizing hints” that breast feeding might also be beneficial for human babies who will develop cystic fibrosis.

Thus, at his clinic and others, mothers of babies with the cystic fibrosis gene are strongly encouraged to breast feed. In future studies, the researchers will try to determine whether adding DHA to infant formula is equally beneficial and whether nursing mothers should take supplemental DHA.

O’Sullivan, Brian P. et al. Association of cystic fibrosis with abnormalities in fatty acid metabolism. New England Journal of Medicine 350, 560-569 (February 9, 2004).
Alvarez, J.G. et al. A membrane lipid imbalance plays a role in the phenotypic expression of cystic fibrosis in cftr (-/-) mice. PNAS 96, 13995-14000. (November 23, 1999).

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