IFNG and hemophagocytic syndrome: Emapalumab, a human mAb against interferon (IFN)γ is indicated (but not yet widely available in the UK or Europe) in primary HLH and MAS, supported by successful clinical trial data in children [82] or in HLH associated with Ebstein-Barr virus infection [18], and anifrolumab, a type I IFN receptor antagonist although not licensed in children, is emerging as potentially efficacious (off-license) in the management of autoinflammatory type I interferonopathies [83, 84].