The incidence of ICI pneumonitis ranges from 5% to 19% [6], being higher with programmed cell death protein 1 (PD-1) inhibitors than with programmed cell death ligand 1 (PD-L1) and cytotoxic T lymphocyte-associated protein 4 (CTLA-4) inhibitors [7]. The gene discussed is CTLA4; the disease is pneumonitis.