Blau syndrome, clinical and genetic aspects

Blau syndrome (BS) is a rare autosomal dominant, autoinflammatory syndrome characterized by the clinical triad of granulomatous recurrent uveitis, dermatitis and symmetric arthritis. The gene responsible for BS has been identified in the caspase recruitment domain gene CARD15/NOD2. In the majority of patients, the disease is characterized by early onset, usually before 3–4 years of age. The manifestations at disease onset are usually represented by articular and cutaneous involvement signs, generally followed later by ocular manifestations which are often the most relevant morbidity of BS. In some cases the presence of fever is also observed; atypical cases of BS have been reported with cardiovascular, neurological, renal, intestinal and other organ involvement. The rarity and the variations in the severity and evolution of its expressions do not permit sufficient data about optimal treatment for patients with BS. The first step of therapy is represented by the use of corticosteroids and successively, in case of unsatisfactory response, by additional treatment with immunosuppressive agents. The results with biologic anti-cytokine agents, such as anti-TNFα and anti-IL1β, are different, particularly with regard to ocular morbidity. Clinical and genetic aspects of the familial and the sporadic form of BS will be discussed and focused on. A description of a case study of an Italian family is also included.

► Blau syndrome is an autosomal dominantly inherited disorder.
► BS-associated NOD2 mutations occur in the NACHT domain.
► Cells expressing BS-mutated forms of NOD2 show increased NF-κB activation.
► Eye involvement is the most relevant morbidity of Blau syndrome.
► Atypical cases of Blau syndrome have been reported with visceral involvement.