The SC formulation filled a previously unmet need related to C1INH replacement: the pharmacodynamic profile of C1INH(SC) is characterized by steady state levels of functional C1INH activity above the ∼40% threshold required for adequate protection from HAE attacks—this is distinct from the IV formulation, which is characterized by more variable peaks and troughs, with the trough levels below the ∼40% threshold.29, 30. This evidence concerns the gene SERPING1 and hereditary angioedema.