PTGS2 and breast cancer: In breast cancer, methylation of specific loci in ERT (NUP155 and ZNF217), PCGT (TITF1, NEUROD1, and SFRP1), and DMHR (PTGS2) of DNA from extracted peripheral blood cells was associated with breast cancer risk.13 Flanagan et al10 compared the methylation pattern of peripheral blood DNA using a custom methylation microarray analysis covering 4 Mb with 51 candidate genes from 14 bilateral breast cancer cases and 14 normal controls and validated their initial findings regarding the tiled region around ATM in 190 pairs of cases and controls.