A Study of Lanadelumab in Teenagers and Adults to Prevent Acute Attacks of Non-histaminergic Angioedema With Normal C1-Inhibitor (C1-INH)

This study consists of non-histaminergic normal C1-INH angioedema population with 12 years of age and above. Participants will be randomized 2:1 to receive repeated SC administrations of lanadelumab or placebo in a double-blind fashion. Randomization will be stratified based on baseline angioedema attack rate (1 to less than (\<) 2 attacks/4 weeks, and greater than (\>=) 2 attacks/4 weeks), as well as subtype (known mutations, family history and unknown mutation, idiopathic).