Specifically, Brown et al. reported heterozygous gain-of-function mutations in TLR7 to cause recurrent hemichorea requiring treatment with haloperidol in the context of a systemic lupus-like phenotype, also describing a patient with an exclusively neurological presentation i.e. of neuromyelitis optica with positivity for AQP4 autoantibodies (33) (with a well-recognised causal link between neuromyelitis optica and enhanced type 1 interferon signalling (34)). This evidence concerns the gene AQP4 and neuromyelitis optica.