At 5 years following therapy initiation, patients receiving anti-PD-1/CTLA-4 combination immunotherapy exhibited significantly higher risk for immune-related meningitis (1.4% vs. 0.56%, OR: 2.6, 95% CI: [1.7,4.0]) and encephalitis (1.3% vs. 0.52%, OR: 2.5, 95% CI: [1.6, 3.9]) encounter diagnoses. The gene discussed is CTLA4; the disease is viral encephalitis.