 The analysis of 630 human primary tumors in 11 tissues shows that "WRN" promoter hypermethylation (with loss of expression of WRN protein) is a common event in tumorigenesis.The "WRN" gene promoter is hypermethylated in about 38% of colorectal cancers and non-small-cell lung carcinomas and in about 20% or so of stomach cancers, prostate cancers, breast cancers, non-Hodgkin lymphomas and chondrosarcomas, plus at significant levels in the other cancers evaluated.The WRN helicase protein is important in homologous recombinational DNA repair and also has roles in non-homologous end joining DNA repair and base excision DNA repair.