For anti-CTLA-4 agents, irAEs mainly affect the gastrointestinal system (diarrhea and colitis), skin (dermatitis and pruritus), liver (hepatitis and increased liver function tests), which are dose dependent.53 Differently, anti-PD-1-associated irAEs more often affect the lung (pneumonitis) and the thyroid gland (hyperthyroidism or hypothyroidism)53. The gene discussed is CTLA4; the disease is hepatitis A virus infection.