IDH1 and astrocytoma (excluding glioblastoma): Besides one case where a variant of unknown significance was detected, activating mutations in the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) were found in 5/17 (29.4%) of PMMRDIA, a higher rate as in conventional supratentorial IDH-mutant high-grade astrocytomas (13,6%, 3/22, Table 2).