DICER1 and embryonal rhabdomyosarcoma: DICER1 syndrome1 predisposes to a variety of cancers, including pleuropulmonary blastoma (PPB),2 ovarian Sertoli-Leydig cell tumor (SLCT),3 embryonal rhabdomyosarcoma,4 and kidney tumors.5, , -8 In DICER1 syndrome, most patients bear a germline null mutation in DICER1, and the tumors uniformly bear a second-hit missense substitution at one of five hotspot positions (1705E, 1709D, 1809G, 1810D, and 1813E).