Inheritance of this syndrome is autosomal dominant. It is caused by mutations in a gene called the NOD2/CARD15 gene, which lead to production of an abnormal protein. Mutations in this gene have also been linked to Crohn’s disease. The protein affected in Blau syndrome belongs to the same family as the abnormal protein involved in TRAPS and CAPS. These abnormal proteins leads to overactive inflammation through mechanisms which are not yet understood.
Symptoms are similar to those of a condition called sarcoid, appear in early childhood, and include
- tan coloured rash
- joint pain and swelling, often causing a condition caused “camptodactyly” – a bent finger that the child cannot fully straighten
- red, painful eyes
As in all the inherited fever syndromes there are raised levels of inflammatory markers.
Treatment with steroids and possibly with biological drugs may be effective.