Key Inclusion Criteria:  Males and females currently enrolled in BioCryst-sponsored Study 302 or 204 Able to provide written informed consent. Would benefit from continued berotralstat treatment Acceptable effective contraception  Key Exclusion Criteria:  Pregnancy or breast-feeding Any condition or situation, including medical history that, in the opinion of the investigator or sponsor, would interfere with the subject's safety or ability to participate in the study Use of other medications for long-term prophylaxis of HAE attacks at the Baseline visit or any time during the study. Use of any other investigational medicinal product at the Baseline visit or any time during the study.