MISMATCH CLEAVAGE DETECTS BASE DELETION IN CYSTIC-FIBROSIS GENE

The Delta F508 is the most common defect in the cystic fibrosis (CF) g ene; it involves in a 3-base deletion in codon 508 and results in the loss of a phenylalanine residue at amino acid position 508. Our previo us results have shown the mismatch enzyme cleavage at the mismatch of a DNA dealer in identifying a specific DNA sequence or a point mutatio n. The assay: is simple and reliable. By manipulating the melting temp erature (T-m) for the hybrids of the DNA targets and the deoxynucleoti de probes, the mismatch cleavage as sag's are able to detect the most common defective CF gene, Delta F508. The assays with a Delta F508 and a normal wild-type probe can differentiate the three genotypes, i.e., Delta F508/Delta F508, Delta F508/normal and normal/ normal. Furtherm ore, the addition of ammonium acetate amplifier to the assay for recyc ling the target DNA can increase the sensitivity to a level that is su fficient to detect the mutated target in a few micrograms of genomic D NA without the aid of PCR amplification. The detection of the base del etion, the amplification of sensitivity and the differentiation among the genotypes of normal, carrier Delta F508 and mutant Delta F508 sugg est the useful application of mismatch cleavage in generic diagnosis a t the DNA level.