Identification of an APC mutation in a pedigree of AFAP with desmoid tumors. (a) The pedigree of the family assessed in this study. Open square: normal male individual; closed square: affected male individual; open circle: normal female individual; closed circle: affected female individual; slash: deceased individual; and arrow: proband. (b) Validation of the 4-bp deletion in APC. Direct sequencing of the PCR products of DNA from a healthy volunteer and a patient revealed a deletion of TTAT at codon 2644 of the APC gene. The amino acid code and position are shown. The red square indicates the four nucleotides deleted in the patient’s DNA. AFAP, attenuated familial adenomatous polyposis; APC, adenomatous polyposis coli.