Canadian and American researchers appear to have pinpointedthe physiological function of the protein for which the genethat causes cystic fibrosis (CF) codes.

Reporting in last week's Cell, a team led by John Riordan at theHospital of Sick Children in Toronto, said the protein, dubbedthe CF transmembrane conductance regulator, or CFTR, is verylikely a transmembrane chloride channel. The work confirms areport from Michael Welsh's group at the University of Iowa,published in the Feb. 8 issue of Science.

CF is the most common lethal genetic disease in whites. Causedby a mutation in the CF gene, it is associated with an array ofcomplications, including the buildup of thick mucus in thelungs, which leads to chronic lung infections. Most victims diefrom respiratory failure while still in their 20s.

Since 1985, researchers have known that many symptoms ofCF could be explained by a defect in chloride transport acrossepithelial cell membranes.

In 1989, three research teams showed that the insertion of ahealthy CFTR gene into cultured airway cells taken frompatients who died from CF corrected defects in chloridetransport. Although this finding shored up the theory that CFTRwas involved in chloride transport, it failed to shed light onCFTR's exact role.

The latest finding, that CFTR is a chloride channel, goes one stepfurther in describing the etiology of the disease, which the CFFoundation considers a prerequisite to finding a cure.

-- Rachel Nowak BioWorld Staff

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