ENVISION: A Study to Evaluate the Efficacy and Safety of Givosiran (ALN-AS1) in Patients With Acute Hepatic Porphyrias (AHP)

Inclusion Criteria: * ≥ 12 years of age * Diagnosed with Acute Hepatic Porphyria (Acute Intermittent Porphyria, Hereditary Corproporhyria, Variegate Porphyria, aminolevulinic acid (ALA) dehydratase deficient porphyria) * Elevated urinary or plasma porphobilinogen (PBG) or ALA values within the past year, * Have active disease, with at least 2 documented porphyria attacks within the last 6 months * Willing to discontinue or not initiate the use of prophylactic hemin throughout the study. * Women of child bearing potential must have a negative serum pregnancy test, not be nursing, and use acceptable contraception Exclusion Criteria: * Clinically significant abnormal laboratory results * Anticipated liver transplantation * History of multiple drug allergies or intolerance to subcutaneous injections * Active HIV, hepatitis C virus, or hepatitis B virus infection(s) * History of recurrent pancreatitis