TNFRSF1A and TNF receptor 1-associated periodic fever syndrome: In addition, TRAPS patients carrying low-penetrance TNFRSF1A variants may show atypical clinical manifestations and symptoms that mimic other AIDs and/or autoimmune diseases, such as idiopathic recurrent acute pericarditis, thus hindering differential diagnosis (Cantarini et al., 2009, 2010d,e,g, 2012a; Rigante et al., 2011).