[Molecular biological analysis of cystic fibrosis--a model example for the strategy of "reverse genetics"]

The elucidation of the basic defect causing cystic fibrosis (CF) is a paradigm for the application of "reverse genetics" to the analysis of human genetic disease. Following this strategy, linkage analysis localized the responsible gene for CF on chromosome 7. Chromosome mediated gene transfer and chromosome walking and jumping led to the isolation of the CFTR-gene and its cDNA. A major 3 bp deletion mutation (DeltaF508) and more than 100 other mutations of this gene have been identified as molecular basis of cystic fibrosis. The CFTR-amino acid sequence, obtained by conversion of the cDNA-sequence, indicates that CFTR belongs to a group of integral membrane transport proteins (ABC-proteins). The normal cAMP-stimulated chloride-transport, lacking in CF-cells is restored by transfer and expression of CFTR-cDNA-recombinants in these cells. CFTR is most likely itself a chloride channel. The molecular identification of this gene has already led to substantial advances in diagnosis and prevention of this disease. New therapeutic approaches by pharmacological means or gene therapy are expected from the further molecular and functional analysis of the CFTR-gene.