Hemophilia B is a rare inherited X-linked disorder characterized by a congenital anomaly in the factor IX gene leading to a variable deficiency in clotting factor IX. In this episode, we explore the known differences between Hemophilia B and Hemophilia A and discuss priority areas for further research into Hemophilia B. The episode also guides listeners on an entertaining journey through 19th and 20th century European monarchy and the unlikely role that hemophilia played in forever shaping Europe’s governance!    Contributors: Bethany Samuelson Bannow, MD Brian O'Mahony Kathaleen M. Schnur, MSW, LCSW   Senior Advisor: Donna DiMichele, MD   Episode Advisors (also contributors): Dr. Amy Shapiro Professor Jan Astermark   Hosted by: Laurence Woollard   Links to learn more:   Brown A. "The Royal Disease and The Royal Collapse: Political Effects of Hemophilia in the Royal Houses of Europe." Honor Scholar Theses. 2017;63. [Online]. Available at: https://scholarship.depauw.edu/cgi/viewcontent.cgi?article=1063&context=studentresearch [Accessed 10 October 2022]   Hoffman TA. "Bad Blood: Hemophilia and Its Detriment to the Russian Imperial Family." Young Historians Conference. 2022;8. [Online]. Available at: https://pdxscholar.library.pdx.edu/cgi/viewcontent.cgi?article=1244&context=younghistorians [Accessed 10 October 2022]   Lannoy N, Hermans C. The ‘royal disease’ – haemophilia A or B? A haematological mystery is finally solved. Haemophilia 2010;16:843-47. Doi: 10.1111/j.1365-2516.2010.02327.x   Potts WTW. Royal haemophilia. J Biol Educ 1996;30(3):207-17. DOI: 10.1080/00219266.1996.9655504   Price KD. "Diary of Nicholas II, 1917-1918, an annotated translation." Graduate Student Theses, Dissertations, & Professional Papers. 1966;2065. [Online]. Available at: https://scholarworks.umt.edu/cgi/viewcontent.cgi?article=3084&context=etd [Accessed 10 October 2022]   Radcliffe J. “Rasputin and the Fragmentation of Imperial Russia.” Young Historians Conference. 2017;14. [Online]. Available at: https://pdxscholar.library.pdx.edu/younghistorians/2017/oralpres/14/ [Accessed 10 October 2022]   Funnell APW, Crossley M. Hemophilia B Leyden and once mysterious cis-regulatory mutations. Trends Genet 2014;30(1):18-23. Doi: 10.1016/j.tig.2013.09.007   Simioni P, et al. X-linked thrombophilia with a mutant factor IX (factor IX Padua). N Engl J Med 2009;361(17):1671-5. Doi: 10.1056/NEJMoa0904377   Nogami K, et al. Clinical conditions and risk factors for inhibitor-development in patients with haemophilia: A decade-long prospective cohort study in Japan, J-HIS2 (Japan Hemophilia Inhibitor Study 2). Haemophilia 2022;28(5):745-59. Doi: 10.1111/hae.14602   Thorland EC, et al. Anaphylactic response to FIX replacement therapy in haemophilia B patients: complete gene deletions confer the highest risk. Haemophilia 1999;5(2):101-5.    Chitlur M, et al. Inhibitors in factor IX deficiency a report of the ISTH-SSC international FIX inhibitor registry (1997-2006). Haemophilia 2009;15(5):1027-31. Doi: 10.1111/j.1365-2516.2009.02039.x   DiMichele D. The North American Immune Tolerance Registry: contributions to the thirty-year experience with immune tolerance therapy. Haemophilia 2009;15(1):320-8. Doi: 10.1111/j.1365-2516.2008.01880.x   Astermark J, et al. The B-Natural Study – The outcome of immune tolerance induction therapy in patients with severe haemophilia B. Haemophilia 2021;27(5):802-13. Doi: 10.1111/hae.14357   Iorio A, et al. Establishing the prevalence and prevalence at birth of hemophilia in males: a meta-analytic approach using national registries. Ann Intern Med 2009;171(8):540-46. Doi: 10.7326/M19-1208   Soucie JM, et al. Occurance rates of haemophilia among males in the United States based on surveillance conducted in specialized haemophilia treatment centres. Haemophilia 2020;26(3):487-93. Doi: 10.1111/hae.13998   Berntorp E, et al. Quality of life in a large multinational haemophilia B cohort (The B-Natural Study – Unm