In vivo, IFN‐γ is found in human tuberculosis and leprosy granulomas (Ma et al, 2021; Gideon et al, 2022) and in non‐infectious granulomatous disease such as sarcoidosis (Ramstein et al, 2016; Damsky et al, 2022) and Blau syndrome (Wouters et al, 2014). The gene discussed is IFNG; the disease is Blau syndrome.