SERPING1 and hereditary angioedema: LTP with intravenous (IV) C1INH (Cinryze®; Takeda) is a well-tolerated treatment that reduced the frequency of HAE attacks in a crossover study from 12.73 attacks in the 12-week placebo period to 6.26 attacks in the 12-week IV C1INH LTP period (P<0.001) (4).