This indicates that colon cancers may arise from CcOI deficient patches of crypts, but this CcOI deficiency may occur and grow into a large patch at a later stage in progression to colon cancer than deficiency for Pms2, Ercc1 or Xpf, which may occur in as many as 1 million crypts surrounding colon cancers. The gene discussed is ERCC4; the disease is malignant colon neoplasm.