20q deletions can occur in various myeloid disorders, e.g., myelodysplastic syndromes (MDS), acute myeloid leukemia (AML), and myeloproliferative neoplasms (MPNs). In MDS, del(20q) as the sole cytogenetic abnormality is associated with a favorable prognosis, with better survival, and a lower risk for transformation to AML. Del(20q) occurring with additional cytogenetic aberrations predicts a poor prognosis. The breakpoints of the 20q deletion were identified to be heterogeneous in several studies. The minimal common deleted region (CDR) was defined to be flanked by the genes PTPRT (20q12) and EYA2 (20q13.12). It has been suggested that one or more tumor suppressor genes could be located in the CDR, the deletion or inactivation of which may play a role in malignant growth. However, the target gene(s) remain unknown.