Open-Label, Long-Term Extension Study to Investigate the Safety, Tolerability, and Efficacy of DISC-1459 (Bitopertin) in Participants With EPP

Inclusion Criteria: Participants with diagnosis of EPP who are participating (or who have participated) in a prior Disc Medicine bitopertin study and who have completed the randomized treatment phase and End-of-Study visit Aged ≥12 years upon study consent Body weight ≥32 kg for participants <18 years of age and BMI ≥18.5 kg/m2 for adult participants Exclusion Criteria: Participants who have an ongoing SAE from a clinical study that is assessed by the investigator as related to bitopertin Other medical or psychiatric condition or laboratory finding not specifically noted above that, in the judgement of the Investigator or Sponsor, would put the participant at unacceptable risk or otherwise preclude participation in the study Condition or concomitant medication that would confound the ability to interpret clinical, clinical laboratory, or participant diary data, including a major psychiatric condition that has had an exacerbation or required hospitalization in the last 6 months Planned treatment with afamelanotide or dersimelagon during the study Planned use of any drugs or herbal remedies known to be strong inhibitors or inducers of cytochrome p450 (CYP)3A4 enzymes throughout the study If female, pregnant, or breastfeeding Participation in any other clinical protocol or investigational trial, other than Disc Medicine bitopertin trials, that involves administration of experimental therapy and/or therapeutic devices within 30 days of Day 1 Score of PHQ-8 ≥10 at screening or any response of "yes" on the C-SSRS Grapefruit/Seville orange and products containing these for 14 days prior to first dose of study drug and throughout the stud