Our result revealed that the mRNA expressions of C1R, C6, C7, C9, CFP, CFHR3, and MASP1 were significantly downregulated in HCC tissues (n = 268) compared with normal liver tissues (n = 243), with a fold change >2 or <0.5 and p‐value < .05 (Table 2), while the expression of the rest complement genes showed no difference between HCC samples and normal tissues. The gene discussed is C7; the disease is hepatocellular carcinoma.