The ~11 kb
deletion is found in two other
mutation-negative kindreds. (A, C) Affected members of kindreds 0130 and 0163 have the classical FAP phenotype, and standard genetic testing of probands IV-1 in kindred 0130 and III-2 in kindred 0163 (arrows) did not identify known pathologic mutations of APC. Second-generation sequencing across the APC locus in the probands suggested that both had the same heterozygous ~11 kb APC deletion found in the index kindred 0124. Sanger sequencing using primer 3 confirmed the presence of the same deletion coordinates from chr5:112,034,825 to chr5:112,045,846 in the probands 0130 (IV-1) (B) and 0163 (III-2) (D). Sequencing using primer 2 in both probands showed the presence of a normal allele as well, with contiguous coordinates from chr5:112,034,825 to chr5:112,034,826.