Enhanced detection of mutations in BRCA1 exon 11 using restriction endonuclease fingerprinting-single-strand conformation polymorphism

A novel approach to mutation screening in the large exon 11 (comprising 342 7 bp) of the human BRCA1 gene is presented. Restriction endonuclease finger printing single-strand conformation polymorphism (REF-SSCP) is based on rep eated detection of DNA sequence variants in different restriction endonucle ase fragments, and we evaluated the method using blood samples from 25 Norw egian patients with hereditary breast/ovarian cancer. We compared REF-SSCP to constant denaturant gel electrophoresis (CDGE) and to the protein trunca tion test (PTT). REF-SSCP detected 12 different DNA variants. Four of these were not detected by CDGE, and only one variant detected by CDGE was misse d by REF-SSCP. PTT detected 4 of these 13 variants. REF-SSCP was subsequent ly applied to a second patient series (Swedish, n=20). A total of 14 differ ent DNA variants were detected by REF-SSCP, 6 of which were truncating muta tions (PTT detected only 4). Nonsense and frameshift mutations that are put ative breast/ovarian cancer mutations, were detected in 7 of the 25 Norwegi an and 9 of the 20 Swedish patients.