IL6 and periodic fever syndrome: This speculation is in line with the observations that patients carrying a D324 mutation had periodic fever syndrome and intermittent lymphadenopathy, overproduction of inflammatory cytokines and chemokines, splenomegaly, hepatomegaly, lymphocyte count/percentage increase, and/or monocyte percentage increase in PBMCs and that these patients responded to the IL-6 inhibitor tocilizumab but did not respond to TNF inhibitors [28,29].