FAS and systemic lupus erythematosus: Defective apoptosis has been implicated in autoinflammatory settings, including SLE.21 Efficient apoptosis can be impaired by upregulation of anti‐apoptotic factors such as cellular FLICE‐inhibitory protein (encoded by CFLAR), previously reported to be upregulated in blood B cells of patients with SLE, and correlating with disease severity.21 This likely prevents apoptosis signalling in response to ligands such as TRAIL and Fas ligand, to allow aberrant survival of autoreactive cells.21 Our stratification found substantial CFLAR overexpression in C3 and C4 (Figure 4c).