D20S108 deletion, del(20q12)
A large number of hematologic malignancies such as myelodysplastic syndromes (MDS), acute lymphocytic leukemia (ALL), polycythemia vera, chronic neutrophilic leukemia, etc. show this anomaly. Deletion of 20q12 affects a small fragment (about 8 Mb) flanked by D20S206 and D20S119 regions, and appears as a primary karyotype abnormality occurs in a pluripotent hematopoietic stem cell, which confers a proliferative advantage to myeloid cells through the suppression of a tumor suppressor gene. Among the genes that are suppressed in this region are TPO1 (topoisomerase 1), PLC1 (phospholipase C), HNF4 (hepatocyte nuclear factor 4) and ADA (adenosine désaminase).
In SMD, del(20q) is associated with a good prognosis.