Deficiency of adenosine deaminase 2 (DADA2) is a complex monogenic autoinflammatory disease first described in 2014 by two separate groups as a syndrome of recurrent fever, livedo racemosa, early-onset strokes, and peripheral vasculopathy resembling polyarteritis nodosa (PAN) (18, 19). This evidence concerns the gene ADA2 and polyarteritis nodosa.