Anti-neutrophil cytoplasmic antibody-associated systemic vasculitis: nature or nurture?

This review examines the environmental and genetic contributions to the anti-neutrophil cytoplasmic antibody-associated systemic vasculitides. The dominant environmental risk factors appear to be silica exposure for all three syndromes, and vitamin D deficiency is strongly suggested by the latitude and ultraviolet radiation gradient observed for Wegener's granulomatosis and ChurgStrauss syndrome. Genetic factors are generally not very strong, consistent with the rarity of these conditions in children. However, multiple genetic factors, each with a relatively small effect, may combine to create a state of susceptibility towards autoimmunity. With infection as a triggering agent, it is possible to synthesise a pathogenetic hypothesis that accounts for both environmental and genetic effects in regard to both necrotising vasculitis and granuloma formation.