Despite harboring LOH3 cells, the GEP of this tumor is class 1, most likely because LOH3 is in a small subclone and a BAP1 mutation has not occurred, consistent with the notion that the class 2 GEP requires LOH3 and mutation of BAP1 on the other copy of chromosome 3 (ref. 12). The gene discussed is BAP1; the disease is neoplasm.