Definition:

Blau syndrome is an autosomal dominantly-inherited disease which is presented with triad of juvenile-onset granulomatous arthritis, uveitis, and skin rashes. Inflammation of the eyes, camptodactyly and lymphaedenopathy are additional features of the disease. Missense mutations in the NOD region of NOD2 underlie Blau syndrome, augmenting NOD2 activity even in the absence of pathogenic stimuli. Inflammation seen in patients with Blau syndrome might be due to an aberrant activation of NOD2 and constitutive NF-kappaB activation. Blau syndrome usually occurs in children younger than age 4 years.