C1S and hereditary angioedema: However, despite the advances in diagnostics and therapeutics, the ongoing burden of disease and the significant unmet needs of people living with HAE were highlighted in the USA FDA survey [23] in which two-thirds of patients, despite their use of prophylactic medications (primarily C1 esterase inhibitor products or androgens) over the previous year(s), still experienced a high frequency of attacks, and a high rate of anxiety and depression.