The BMN 270 clinical development program consists of multiple interventional studies designed to assess the safety and efficacy of a single infusion of BMN 270 for at least 5 years post-infusion. This long-term follow-up study is needed to help further understand the long-term safety of BMN 270 beyond 5 years and to assess the durability of efficacy.

Study 270-401 will collect additional follow-up data in a single study for approximately 10 years among all subjects who consent to participate and have completed their primary treatment study (ie, for any study in which they received BMN 270).

Inclusion Criteria:

• Participants must have completed their primary treatment study or be currently enrolled in the primary treatment study at the time of closure by the Sponsor. Participants may enroll in 270-401 even if they have restarted FVIII prophylaxis or other hemophilia A treatment.
• Subjects must be capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol. If the subject is unable to provide consent, a legally authorized representative may provide written informed consent.

Exclusion Criteria:

• Participants who do not directly enroll in 270-401 at the time of the study completion visit in their primary treatment study should enroll in 270-401 within 4 months of the date of that study completion visit. If a participant wishes to enroll in 270-401 after 4 months, they must receive prior approval from the Medical Monitor.
• Participants must be overtly healthy and not have any condition that, in the opinion of the Investigator or Medical Monitor, would prevent the participant from fully complying with the requirements of the study and/or would impact or interfere with evaluation and interpretation of the study data (including, if applicable, advanced HIV disease).
• Where applicable, per country regulation, the participant must not currently be committed to an institution by virtue of an order issued either by judicial or administrative authorities.

Subjects must have completed their primary treatment study in which they were dosed BMN 270. Subjects may enroll in 270-401 even if they have restarted FVIII prophylaxis or other hemophilia A treatment.