(a) Abbreviated pedigree of the index family, G334R-1 showing three mutation positive individuals (denoted with “+”) and two obligate carriers (mother and maternal uncle of proband, denoted with “oc”). Both proband and mother have multiple primary LFS-component cancers (breast, sarcoma, colon, and brain cancers). Mutation positive individuals (“+”) underwent either targeted panel testing clinically or site-specific TP53 testing. (b) Abbreviated pedigree of family G334R-6 showing tracking of the mutation (denoted with “+”) from a proband with multiple primary LFS-component cancers (breast, sarcoma) to her great-nephew with an ACT. Mutation positive individuals (“+”) underwent either targeted panel testing clinically or site-specific TP53 testing. (c) Abbreviated pedigree of family G334R-4 showing a mutation positive sib ship (denoted with “+”) both with ACTs. Mutation positive individuals (“+”) underwent either targeted panel testing clinically or site-specific TP53 testing. (d) Identification of a Chromosome 17 c.1000G>C haplotype from position 6,653,587 to 8,868,384 (GRCh37/hg19) in four independent families. Schematic diagram of chromosome 17 showing the identification and location (based on GRCh37) of genotyped SNPs and microsatellites analyzed in haplotype determination. The shared common haplotype is represented by a green bar in the pedigrees. Families used for identification of the haplotype are G334R-1, -2, -3, -6.