A Study Evaluating the Efficacy and Safety of Mitapivat in Participants With Non-Transfusion-Dependent Alpha- or Beta-Thalassemia (α- or β-NTDT)

Inclusion Criteria: * Documented diagnosis of thalassemia (β-thalassemia with or without α-globin gene mutations, hemoglobin E (HbE)/β-thalassemia, or α-thalassemia/hemoglobin H \[HbH\] disease) based on Hb electrophoresis, Hb high-performance liquid chromatography (HPLC)), and/or deoxyribonucleic acid (DNA) analysis; * Hb concentration ≤10.0 grams per deciliter (g/dL) (100.0 grams per liter \[g/L\]), based on an average of at least 2 Hb concentration measurements (separated by ≥7 days) collected during the Screening Period; * Non-transfusion-dependent, defined as ≤5 red blood cell (RBC) units during the 24-week period before randomization; and no RBC transfusions ≤8 weeks before providing informed consent and no RBC transfusions during the Screening Period; * If taking hydroxyurea, the hydroxyurea dose must be stable for ≥16 weeks before randomization; * Women of child-bearing potential (WOCBP) must be abstinent of sexual activities that may result in pregnancy as part of their usual lifestyle or agree to use 2 forms of contraception, one of which must be considered highly effective, from the time of providing informed consent, throughout the study, and for 28 days after the last dose of study drug. The second form of contraception can be an acceptable barrier method; * Written informed consent before any study-related procedures are conducted and willing to comply with all study procedures for the duration of the study. Exclusion Criteria: * Pregnant, breastfeeding, or p…