Hemophilia B

Hemophilia B, also known as Christmas disease, is the second most prevalent form of hemophilia. A defect in the gene causes hemophilia B, leading to inadequate production of factor IX. The genetic defect can occur either through X-linked inheritance or a spontaneous de novo mutation. Although this condition predominantly affects males, the carrier females may also occasionally experience more significant bleeding symptoms. Heterozygous women with the genetic mutation may have varying levels of factor IX, and those with levels at or above 50% of normal are usually asymptomatic. Named after the first diagnosed case in 1952, Stephen Christmas, this disorder earned the moniker "the royal disease" due to its notable presence in the royal families of Spain, Germany, England, and Russia. Clinical presentations of the disease vary in severity, with males affected by the severe form displaying spontaneous and severe bleeding at birth. In contrast, individuals with milder cases usually experience bleeding primarily after trauma or surgery, and symptoms may not become apparent until later in life. This topic comprehensively explores the genetic causes, clinical manifestations, potential complications, and the pivotal role of genetic testing in diagnosing hemophilia B, assessing disease severity, determining female carrier status, and informing decisions related to obstetrical care.