DNA sequence analysis of the KM19 locus linked to cystic fibrosis. Design of new oligonucleotides to remove non-specific PCR products.

The PstI polymorphism detected by probe KM19 is a highly informative marker in linkage disequilibrium with the cystic fibrosis locus and has been used extensively for prenatal diagnosis. The currently available primers used for polymerase chain reaction- (PCR-) based analysis of this locus have been shown to produce spurious amplification products. In this report, we describe the sequence of the KM19 locus and the major contaminating PCR product. We have used this information to design a more specific amplification procedure for analysis of the KM19 locus.