Direct gene diagnosis of cystic fibrosis by allele-specific polymerase chain reactions.

Cloning of the cystic fibrosis gene and the identification of the predominant disease-causing mutation did not only help in the understanding of this frequent disease, but was immediately followed by applications in direct gene diagnosis. We describe a method for the detection of the so-called delta F508 deletion, which accounts for 70% of the mutations: a polymerase chain reaction with two different combinations of oligonucleotide primers, which discriminate between mutant and wild-type alleles. This allele-specific amplification provides a rapid, non-radioactive and very reliable method for direct genotyping. Establishment of the procedure and its application in diagnosis are described. We further report preliminary data on the frequency of this mutation in German patients and its association with restriction fragment length polymorphism haplotypes.