DICER1 and neoplasm: DICER1-related tumor predisposition therefore represents an unusual form of Knudson’s two-hit hypothesis, since the somatic mutation affects the ability of DICER1 RNase IIIb domain to process 5p miRNAs, while keeping its capacity to generate 3p miRNAs by the preserved RNase IIIa domain (2, 3, 12).