Genetic component of giant cell arteritis.

Important steps forwards have been taken during recent years towards the understanding of the genetic basis of autoimmunity. The increasing number of study cohorts is allowing better characterization of the genetic component of most autoimmune diseases. However, the molecular mechanisms leading to some less common diseases remain poorly understood. GCA, an antigen-driven systemic vasculitis affecting medium and large blood vessels of elderly people, represents one of these cases. However, although underpowered to detect low to moderate effect sizes and without replication steps, many genetic studies on this disease have been published in the past decade. These reports clearly point to genes located in the MHC region, in particular HLA-DRB1*04 alleles, and other key members of the immune and inflammatory response (including cytokines, adhesion molecules and regulators of innate immunity), as crucial players in the development and progression of GCA. Considering that no literature review has been published so far about the genetic component of this vasculitis, we aimed to summarize here the current knowledge on the genetics underlying GCA predisposition and severity.