APP and ependymoma: Tumor somatic SNVs are uncommon in HLA and APP genes, whereas HLA LOH caused by CNVs was heterogenous depending on the tumor types and subtypes; it was globally low (< 10%) in neuroblastoma, nephroblastoma and ependymoma, but elevated in osteosarcoma and GBM for class I and II genes (up to ~24%), and in Ewing sarcoma and LGG for class II genes (up to 50%).