Yo Abs bind to the cytoplasmic antigen of cerebellar degeneration-related protein 2 (CDR2, 50 kDa, RefSeq NM_001802.1) and 2-like (CDR2L, 62 kDa, RefSeq NM_014603.2) and are found in the serum and cerebrospinal fluid of patients with remote, non-metastatic ovarian and breast cancers [7, 22, 72]. This evidence concerns the gene CDR2 and breast cancer.