Of note, this tumor also harbored a focal loss affecting chr13q14.2 (including RB1; Fig. 3b), that was only present in the ependymoma component, suggesting biallelic inactivation of RB1. The four likely pathogenic variants comprise missense variants in the PTPRD and TSC2 tumor suppressor genes [#34 and #42: PTPRD exon14:c.T2243A:p.L748Q (NM_001171025) and #38 and #40 TSC2 exon2:c.G76A:p.E26K (NM_001318829)], but variant allele frequencies around 50% suggest heterozygous germline mutations without evidence of copy-number alteration affecting the other allele in those cases. This evidence concerns the gene RB1 and ependymoma.