IDH1 and subependymoma: After excluding 45 cases that did not meet the inclusion criteria (4 patients aged < 18 years old, 8 ependymomas, 4 subependymomas, 9 patients with other concomitant tumors, and 20 patients with missing ATRX, p53, IDH1, or Ki-67 testing results), a total of 257 patients were finally included in the study (Figure 1).