p-ANCA positivity can be used as a diagnostic marker for UC and has also been reported in 10-80% of UC patients who do not have complicated AAV. PR3-ANCA positivity, which is equivalent to c-ANCA, has been shown to have a sensitivity of 58% and a specificity of 93% in the differential diagnosis of UC and CD [10]. This evidence concerns the gene PRTN3 and anti-neutrophil cytoplasmic antibody-associated vasculitis.