A 9.5-year-old boy was referred with a 2-year history of recurrent fever, myalgia, abdominal pain and various neurological manifestations associated with increased acute phase reactants and IgG level. During the recent episode, severe hypertension and right-sided hemiparesis developed and angiography demonstrated irregularities and stenosis in renal and mesenteric artery branches. Although these manifestations were consistent with polyarteritis nodosa (PAN), the consanguinity of his parents, a cousin with similar clinical features and early disease onset led to suspicion of deficiency of adenosine deaminase type 2 (DADA2) diseases. DADA2 was established by demonstration of decreased ADA2 enzyme activity and a homozygous G47R mutation in the CECR1 gene. The diagnosis of DADA2 is challenging because of the overlapping manifestations with PAN and other periodic fever syndromes. DADA2 should be considered in the differential diagnosis of PAN. Raised IgG levels (usually low in DADA2) should be sought in future cases.