Quantitative PCR (qPCR) analysis confirmed that the transcriptional levels of key inflammatory genes, such as TNF, IFNA2, IFIT1, ISG15 and RSAD2, were also upregulated in PBMCs from patients P1 and P2 compared with in the healthy controls at the basal level and after CpG-DNA stimulation, whereas CpG-DNA-stimulated PBMCs from patients with SLE without PLD4 mutations exhibited minimal responses (Fig. 3e). Here, PLD4 is linked to systemic lupus erythematosus.