Frequency of the delta F508 mutation and XV2c,KM19 haplotypes in cystic fibrosis families from The Netherlands: haplotypes without delta F508 still in disequilibrium.

We have determined the frequency of the major cystic fibrosis (CF) three base pair deletion (delta F508) mutation in 152 CF chromosomes from patients originating from the northern part of The Netherlands. In these patients, the deletion represents approximately 76% of CF mutations. Meconium ileus is strongly associated with homozygosity for the delta F508 mutation. The XV2c,KM19 haplotypes on the CF chromosomes without the delta F508 mutation are in disequilibrium with the population frequency, although showing an increased frequency of the 1 2 haplotype. The surplus of this haplotype is almost entirely made up by the pancreatic insufficient patients.