The following keywords were used: inborn errors of immunity, primary immunodeficiency, pediatrics, Toll-like receptors, TLR3, TLR7, TLR8, MYD88, IRAK4, UNC93B1, TRIF/TICAM1, TBK1, IRF3, IRF7, TRAF3, HSV-1, encephalitis, pyogenic infections, functional diagnostics, whole blood stimulation, fibroblasts, whole genome sequencing, rWGS, interferon, immunomodulation, TLR7/8 inhibitors, IRAK4 inhibitors, juvenile SLE, chilblain lupus, antibiotic prophylaxis. The gene discussed is IRAK4; the disease is systemic lupus erythematosus.