Hameister and Adolph's [3] originalclaim that the human X chromosome is depleted of cancer genes has beenchallenged by new analyses of human genome data, which show that the human Xcontains many primate-specific families of cancer genes such as the synovialsarcoma X (SSX) breakpoint family; the cancer/testis antigen families: CT45,CTAG, SPANX, plus the GAGE cancer/testis antigen subfamilies: XAGE, PAGE,and MAGE, which appear to be amplified within large palindromes. This evidence concerns the gene CT45A1 and cancer.