RB1 and astrocytoma (excluding glioblastoma): In PMMRDIA, the RB1 gene was affected by point mutations more frequently (23.5% vs. 4.6%) whereas deletions of CDKN2A/B were present less frequently (35% vs. 70%) compared to the reference cohort of high-grade supratentorial IDH-mutant astrocytomas (Fig. 4).