Allelic tumor-specific methylation. Data from six patients who are germline heterozygous for a SNP (rs2854744) in the IGFBP3 promoter. The sequencing reads are aligned as rows in each panel. Each base in the read is color-coded to indicate the sequence: (yellow) a methylated cytosine; (blue) all other bases. The position of the SNP is indicated by the red and white column: (red) reads from the A allele; (yellow) methylated C allele; (white) C allele, if unmethylated and converted to a T. Patient “breast 8” is unmethylated on both alleles in both the tumor (left column) and normal tissue (right column). Patients “breast 4” and “colon 6” display tumor-specific methylation on only one allele, and the methylated allele differs between them. Patients “colon 7” and “colon 12” display tumor-specific methylation on both alleles. Patient “colon 12” displays different patterns of methylation on each allele in the tumor.
