We note, however, that it remains possible that lower grade IDHm astrocytomas with high level (≥ 30%) CDKN2A deletion by FISH do in fact have a poor prognosis, but given the rarity of grade 2 or 3 tumors exceeding this threshold, there is insufficient evidence to determine the prognostic impact of this finding in our cohort. This evidence concerns the gene CDKN2A and astrocytoma (excluding glioblastoma).