Haplotype analysis for CF-linked DNA polymorphisms in Switzerland.

A total of 295 patients, parents and unaffected sibs from 106 CF-families in central and northeastern Switzerland were investigated with probes 7C22(D7S16), metH, metD, pKM19, pXV-2c and pJ3.11(D7S8) for eight DNA polymorphisms (RFLP's). Linkage disequilibrium to the CF locus and haplotype frequencies were compared to those in other populations. They are comparable to other Caucasian populations and, for pKM 19 and pXV-2c, very close to the findings in Italy. The prevalence of certain haplotypes among the CF and the normal allele-bearing chromosomes indicate that the majority of the CF cases are probably the result of one ancient mutation in a common ancestor, but that there may be allelic heterogeneity accounting for an important proportion of patients, that may differ between countries or regions. Informative family constellations for the different polymorphisms in Switzerland and strategies for carrier detection and prenatal diagnosis are discussed. Haplotype analyses for each country and its ethnic subgroups are recommended.