SERPING1 and hereditary angioedema: Notably, the efficacy of C1-INH products for long-term prophylaxis was generally demonstrated in populations with a more severe HAE phenotype (on-placebo or pretreatment attack rate ∼4‒7 attacks/month) (40, 50, 54) than in similar trials of single-pathway treatment options (∼2–4 attacks/month) (Tables 3, 4) (63, 68).