Type I interferons play an outstanding role in innate and adaptive immunity by 
enhancing functions of dendritic cells, inducing differentiation of monocytes, 
promoting immunoglobulin class switching in B cells and stimulating effector 
functions of T cells. The increased production of IFNα/β by plasmacytoid 
dendritic cells could be responsible for not only efficient antiviral defence, 
but it also may be a pathological factor in the development of various 
autoimmune disorders. The first evidence of a genetic link between type I 
interferons and autoimmune diseases was the observation that elevated IFNα 
activity is frequently detected in the sera of patients with systemic lupus 
erythematosus, and that this trait shows high heritability and familial 
aggregation in their first-degree healthy relatives. To date, a number of genes 
involved in interferon signalling have been associated with various autoimmune 
diseases. Patients with systemic lupus erythematosus, Sjögren's syndrome, 
dermatomyositis, psoriasis, and a fraction of patients with rheumatoid arthritis 
display a specific expression pattern of interferon-dependent genes in their 
leukocytes, termed the interferon signature. Here, in an attempt to understand 
the role of type I interferons in the pathogenesis of autoimmunity, we review 
the recent advances in the genetics of autoimmune diseases focusing on the 
association of genes involved in type I interferon pathways.