XK and neuroblastoma: HLA class I-positive specimens in nephroblastoma, neuroblastoma and rhabdomyosarcoma tumors (45.5, 22.7 and 23%, respectively) showed only low or heterogeneous HLA class I expression (scores 1 to 2), with no apparent difference among tumor subtypes (eRMS vs. aRMS; NB MYCN-A, MYCN-NA, 11qWT vs. 11qLOH) (Figures 6A, B, 7).