We and others have identified both germ-line and somatic mutations in DICER1 that are associated with a range of mainly childhood-onset cancers and dysontogenic or hyperplastic conditions, notably “blastoma”-type tumors such as pleuropulmonary blastoma (PPB), ovarian Sertoli- Leydig cell tumor (SLCT), embryonal rhabdomyosarcoma and Wilms tumor, as well as benign tumors such as cystic nephroma [1-10]. The gene discussed is DICER1; the disease is pleuropulmonary blastoma.