COL18A1 and hereditary angioedema: In addition, the HAE-nC1-INH patients showed the highest C1-INH plasmatic concentration (p = 1.42 × 10−3; one-way ANOVA), while C4 values were midway between those of HAE Type I and Type II patients (p = 5.85 × 10−6; one-way ANOVA).