Family D in whom deletion of exon 20 of the BRCA1 gene was detected. a. Pedigree of family D. Black symbols indicate individuals with cancer. The proband is indicated by an arrow. A red circle inside a symbol indicates individuals found to carry the mutation. (CaBr=breast cancer, CRC=colorectal cancer d.=age of death, N=individual tested for the family mutation and was found to be of normal genotype). b. Long PCR of DNA from three individuals in family D. (M=molecular size marker (λ/HindIII, New England Biolabs, U.S.A.), C=normal control, numbers denote the identifier in the pedigree). c. Schematic representation (not to scale) of the fragment of BRCA1 gene amplified by Long PCR showing the position of exons, restriction endonuclease cleavage sites and the deletion. Empty boxes indicate exons. Vertical colored bars indicate restriction sites: blue (S) = SmaI. Red (H) = HindIII.