CIITA and medulloblastoma: Only two tumors harbored missense mutations in HLA-A CDS, a single one in B2M, and five others in TAP1 and/or TAP2, including one medulloblastoma with mutations in both B2M and TAP2. Interestingly, seven missense mutations in CIITA, the master regulator of HLA class II expression, were detected in five tumors, including three mutations in a medullobastoma with constitutional mismatch repair deficiency (Supplementary Table S12A).