He had discovered and named Christmas disease, a rare form of haemophilia.

"And it is considerably more than Christmas disease, which, by itself, might be ignored in a royal person.

Christmas disease is a hereditary bleeding disorder previously mistaken for hemophilia.

Hemophilia B - also called Christmas disease - is less common and occurs in about 15% of people with hemophilia.

Christmas disease."

Hemophilia B is also known as factor IX deficiency or Christmas disease.

Deficiency of factor IX causes Christmas disease (hemophilia B).

However, during his tryout he was diagnosed with Haemophilia B (also known as Christmas disease), a rare disorder which prevents blood from clotting properly.

Recombinant factor IX is used to treat Christmas disease, and is commercially available as BeneFIX.

The original Christmas disease mutation was identified by sequencing of Christmas' DNA, revealing a mutation which changed a cysteine to a serine.

For instance, deficiency of Factor VIII causes classic Hemophilia A while deficiencies of Factor IX cause "Christmas disease"(hemophilia B).

It is the second most common form of haemophilia, rarer than haemophilia A. It is sometimes called Christmas disease, named after Stephen Christmas, the first patient described with this disease.

Hemophilia B, also known as Christmas Disease, a blood clotting disorder caused by a mutation of the Factor IX gene and leading to a deficiency of Factor IX.

Others are named after patients who were among the first in whom a condition was identified, like Christmas disease, a bleeding disorder also known as hemophilia B that was found in a member of the Christmas family.

The two most common differential diagnoses are haemophilia B (also known as Christmas disease) which is a deficiency in Factor IX and von Willebrand Disease which is a deficiency in von Willebrand factor needed for the proper functioning of Factor VIII.