Distribution of the delta F508 mutation in 194 Spanish cystic fibrosis families.

Spanish cystic fibrosis (CF) families (n = 194) have been analysed for the delta F508 mutation, and for closely linked DNA markers. The delta F508 mutation accounts for 50% of CF chromosomes. Four haplotypes are associated with the deletion, and at least seven haplotypes carry other mutations. The second major CF mutation is associated with pancreatic insufficiency and occurred in the same haplotype in which the delta F508 arose. Only 31% of Spanish CF patients with no family history of the disease can be accurately diagnosed; about 50% of CF carriers can be detected in the Spanish population.