The mean gene expression of defensin alpha-1 was significantly lower in HCV monoinfected and HCV MC vasculitis patients compared to the other two groups [3.80 ± 0.80 (NV), 1.20 ± 0.40 (HCV MC-Vasc), 2.10 ± 0.60 (HCV), 3.7 ± 0.70 (HIV/HCV); p = 0.01 between HCV MC-Vasc and normal and p = 0.03 between HCV viremic and normal], thereby confirming the DNA microarray analysis. This evidence concerns the gene DEFA1 and vasculitis.