LINKING CYSTIC FIBROSIS WITH CHOLERAFurther to the article in Monday's BioWorld Today on theconnection between cystic fibrosis and cholera, an eminentgeneticist told BioWorld Today that the hypothesis linking cysticfibrosis with cholera still needs work.He is Lap-Chee Tsui at the Hospital for Sick Children in Toronto,one of the two geneticists who simultaneously discovered the majorcystic fibrosis gene five years ago. (The other is Frank Collins, thenat the University of Michigan, now director of the Human GenomeProject at the National Institutes of Health.)Lap-Chee Tsui said, "As for Sherif Gabriel's experiment in mice, Ithink his results are credible. The reduction of those secretions inthe cystic fibrosis carrier compared to the normals is very good."But Tsui added that "it is difficult to explain" why the selection ofthe cystic fibrosis gene as protection against cholera "happened inthe past in the Caucasian population, but not in others. Cholera isnot just a Caucasian problem, but could be everywhere."He speculates that there may have been a cholera epidemic in theMiddle East, say, 50,000 years ago, which carriers of the cysticfibrosis gene survived. "If the epidemic were selected for, then itmust have occurred at the time of the migration of peoples from theMiddle East to the rest of Europe."Tsui emphasized that although Gabriel's experiment "is veryattractive, and a very important point in the development of thishypothesis, it's still a hypothesis. I don't think it's a proof." _David N. Leff

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