Genetic analysis of the proband. (A) De novo TLR7 mutation identified by trio-based genome sequencing. (B) Conservation of the affected proline residue across species. (C and D) Location of P435S within the extracellular domain, relative to previously reported pathogenic variants (F507S/L, P267L, Y264H). (E) NF-κB reporter assay in HEK293T cells following R848 stimulation. (F) Sustained type I interferon signaling in the TLR7-GOF patient compared to patients with monogenic type I interferonopathies. HC, healthy controls; SAVI, STING-associated vasculopathy with onset in infancy; TIR, Toll/interleukin-1 receptor/resistance protein; TM, transmembrane; ****P < 0.0001.