Notably, HLA-B, TAP1 and TAP2 transcript levels were lower than the minimum values of control normal tissues (brain and testis) in ~80% of PDXs (32 out of 44), and B2M levels were also low in neuroblastoma, nephroblastoma, and all but one rhabdomyosarcoma tumors. This evidence concerns the gene TAP2 and Wilms tumor.