TNFRSF1A and TNF receptor 1-associated periodic fever syndrome: On the contrary, a more significant variability in terms of clinical phenotype may be observed in TRAPS (Aksentijevich et al., 2001; Dodé et al., 2002; Aganna et al., 2003; Ravet et al., 2006; Cantarini et al., 2009, 2010c,d,e,f,g; Rigante et al., 2011; Brizi et al., 2012): this heterogeneity is largely related to the wide spectrum of known TNFRSF1A mutations, which can be distinguished into high-penetrance and low-penetrance variants (Touitou et al., 2004).