MONDO_0013021 (sterile multifocal osteomyelitis with periostitis and pustulosis) is an autoinflammatory disease caused by mutations in the IL1RN gene, which encodes the IL1 receptor antagonist. It presents in infancy, and is characterized by systemic inflammation, pustular rash, bone pain, sterile osteitis, and periostitis. Also known as: DIRA, Interleukin-1 receptor antagonist deficiency, OMPP, autoinflammatory disease due to interleukin-1 receptor antagonist deficiency, deficiency of the Interleukin-1 receptor antagonist.