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Genomics characterization of primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare malignancy confined to the central nervous system (CNS). Despite low tendency of systemic dissemination, its prognosis is poor with median overall survival of 2?4 years. Due to its rarity, knowledge of genomic alterations underling PCNSL pathogenesis is severely limited. Here we performed whole-exome sequencing on 44 PCNSL and paired normal specimens, revealing high penetrance of nonsynonymous somatic mutations in PIM1 (95.5%), BTG2 (88.6%) and MYD88 (81.8%). Interestingly we found oncogenic mutations in GRB2, and this effect was cancelled when transformed cells are treated with inhibitors to downstream kinases MAP2K1/2. Further, when tumor cells carries MYD88 mutations, the same mutations were also found at low frequency in peripheral blood mononuclear cells (PBMNC), implying that MYD88 mutation?positive precancerous cells originate outside CNS and develop to lymphoma with additional genetic hits that fit the CNS environment.