It has been suggested that various genetic alterations, including small variations and copy number variations in genes, such as SMAD family member 3 (SMAD3), PR/SET domain 1 (PRDM1), interleukin 1 receptor antagonist (IL1RN), CD274, solute carrier organic anion transporter family member 1B1 (SLCO1B1), thyroid stimulating hormone receptor (TSHR) and FANCD2 and FANCI associated nuclease 1 (FAN1), are associated with irAEs, especially some organ-specific irAEs, including hepatitis and encephalitis (72). The gene discussed is FAN1; the disease is viral encephalitis.