RB1 and rhabdomyosarcoma: The PRMS molecular group was devoid of recurrent activating mutations but did have a high frequency of inactivating mutations in tumor suppressors, including TP53, RB1, NF1, and PTEN Similar molecular alterations were identified in the histologically classified pediatric ERMS cases that clustered with the PRMS methylation group, including mutations in RB1 and TP53. No cases of rhabdomyosarcoma with VGLL2, NCOA2, or CITED fusions were identified.