A CLUSTER OF CYSTIC-FIBROSIS MUTATIONS IN EXON 17B OF THE CFTR GENE -A SITE FOR RARE MUTATIONS

Intensive screening has improved our understanding of the profile of m utations in the CFTR gene in which more than 400 mutations have been d etected to date. In collaboration with several European laboratories w e are involved in such analysis. We have identified 14 new mutations i n exon 17b of CFTR, having analysed 780 CF chromosomes, and have compa red the frequency of mutations in this exon with that of other regions of the CFTR gene. The results obtained indicate an accumulation of mu tations, not only in regions encoding the two nucleotide binding folds , but also in those encoding transmembrane domains of the CFTR gene, i n particular exon 17b.