DICER1 and DICER1-related tumor predisposition: Several studies have shown that “monoallelic DICER1 inactivation promotes tumorigenesis, whereas biallelic loss is inhibitory, and although inactivation of one DICER1 allele is the initiating event in DICER1 syndrome”, leading “to dysregulation of miRNA levels, other events must be required for cancer to occur ” (13, 14).