I (don't) wish you a merry Christmas (disease)
Department of Chemistry, University of Bologna
As Announced, today I'm not going to work at all. I just want say thank you for reading all the boring things I like to write and I wish you, all, a lovely Christmas and a lipid-rich Christmas lunch.
What I don't wish you is to get Christmas disease, which is just another name for Haemophilia B. The pathology was named this way after Stephen Christmas, the first patient with this type of haemophilia to be studied. The article describing it was, amazingly, published in the Christmas issue of the British Medical Journal.
Basically, our blood coagulates thanks to the conversion of fibrinogen to fibrin. This is, however, the very last step of a cascade pathway where many clotting factors are involved: at each step a factor undergoes a proteolysis with a particular and personal enzyme, so that in the achieved active form it could activate the enzyme that'll activate the next factor.

Christmas disease is caused by a deficiency of factor IX (also known as Christmas factor), due to mutations in its gene.
This mutation is sadly inherited, as X-linked recessive trait
The disease is clinically indistinguishable from Haemophilia A, which is the major form of haemophilia.
The therapy is based solely on infusions of recombinant factor IX, which is still rather expensive but widely available.
See you tomorrow night. Until then, all the best!
, I obviously knew it and used to read your articles.