Hemophilia

There are different degrees of severity of hemophilia A and B. Clinical severity usually correlates with the individual's circulating FVIII or FIX level Pedigree of hemophilia in the royal families of Europe. Queen Victoria was a carrier of this X-linked trait. Her son Leopold in herited the X chromosome that carried it, while her son Edward VII did not. Adapted from http://ublib.buffalo.edu/libraries/projects/cases/hemo.htm. (determined by doing an FVIII or FIX assay on a venous blood sample). The severity is generally the same in all affected members of a family.

Normal values for FVIII and FIX can range between 50 and 150 percent of the mean value, while severely affected individuals generally have levels of less than or equal to 1 percent, moderately affected persons 1 to 5 percent, and mildly affected persons 5 to 35 percent. Severely affected individuals often have spontaneous joint and muscle hemorrhages, whereas mildly affected persons bleed only with trauma or surgery.