BACKGROUND AND OBJECTIVES: Blau syndrome (BS) is a rare autosomal dominant autoinflammatory disease with limited treatment options, driven by the nucleotide-binding oligomerization domain containing 2 (NOD2) mutations that constitutively activate RIP2-mediated nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs) signaling. The gene discussed is NOD2; the disease is Blau syndrome.