The distribution of the anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitides (AAV) is not uniform across geographical regions and ethnic and racial groups, suggesting that genetic and environmental factors affect the pathogenesis of these diseases. In addition, genetic factors affect not only the clinical syndrome phenotypes and their prognosis, but also ANCA specificity; these data suggest that AAV may need reclassification. Several genes have been evaluated, including ANCA targets and those of the immune system, for example co-stimulatory molecules, signaling regulators, cytokines, Fc and other receptors, and other proteins. This article provides a review of genetic factors affecting the pathogenesis and prognosis of AAV. Further studies to determine the effect of genetic factors on the clinical syndrome phenotypes and ANCA specificity need to be performed across different ethnic groups.