RAC1 and primary central nervous system lymphoma: Significant CN gains in PCNSL mapped to 2q37 and 18q21 affecting DIS3L2 and MALT. DIS3L2 encodes for an exoribonuclease that is responsible for Perlman syndrome104 and was recently described to promote HCC tumor progression by upregulating production of the oncogenic isoform of RAC1, RAC1B105.