Figure 1

Organization of the CFTR gene and BAC clones A) Map showing the organization of the human CFTR gene as 27 exons spread over ~200 kb of chromosome 7q. Note that the original numbering of the exons goes up to 24, but extra exons, such as 6b, were found and numbered later. B) Map of the two overlapping BACs, 68P20 and 133K23, and the regions of homology (HomA, HomB, and HomC) which were used during the subcloning and linking steps.