The reasons are unclear but it was proposed that it can be due to synthetic lethality that occurs only in del(5q) MDS with haploinsufficient CSNK1A1 [109] but fails in AML with normal CSNK1A1 or in del(5q) AML that often carries TP53 mutations. Here, CSNK1A1 is linked to acute myeloid leukemia.