By BioMarin’s count, about 6,500 adults in the U.S. have severe hemophilia A. Of those, the company estimates 2,500 are eligible for Roctavian under the current approval.

Source: https://medcitynews.com/2023/06/fda-approves-biomarin-pharmas-gene-therapy-the-first-for-hemophilia-a/

"Our findings suggest that gene therapy may reduce the burden of care and improve quality of life in patients with hemophilia B," the authors write.

Source: https://www.gjsentinel.com/lifestyle/health_and_wellness/gene-therapy-beneficial-for-patients-with-hemophilia-b/article_e2655ab7-27c7-597d-8ae1-ee921f47084f.html

Relative to site readiness in the U.S., we have identified and are focused on a relatively small number of the largest and most capable hemophilia treatment centers to be ready to treat with ROCTAVIAN at or shortly after launch.

Source: https://seekingalpha.com/article/4582581-biomarin-pharmaceutical-inc-bmrn-q4-2022-earnings-call-transcript?source=feed_all_articles