[17] found no differences between C1‐INH‐HAE patients and controls in a smaller number of subjects, others, including the present authors, have shown higher C1s/C1‐INHc in C1‐INH‐HAE [17, 18, 19] and at times also lower MASP‐1/C1‐INHc levels [20]. Here, C1S is linked to hereditary angioedema.