In PCNSL, target amplicon exome-sequencing using a cancer-related gene panel detects somatic mutations in the exons of serine-threonine kinase pim-1 (PIM1), MYD88, CD79B, dystonin (DST), interferon regulatory factor 4 (IRF4), erb-b2 receptor tyrosine kinase 3 (ERBB3), myosin heavy chain 11 (MYH11), deleted in colorectal carcinoma netrin 1 receptor (DCC), and lysine-specific methyltransferase 2D (KMT2D)21. The gene discussed is IRF4; the disease is cancer.