In honor of tomorrow’s holiday, we have a special guest post from our medical student in the trenches, Richard Huang. Thanks, Richard!

Many of you may already know Christmas Disease as Hemophilia B, but did you know that the condition was originally named eponymously after Stephen Christmas, the first patient to be diagnosed with this coagulation disorder back in 1952? Interestingly, the original article that described the diagnosis was published around Christmas time, and I don’t think that is a mere coincidence.

Hemophilia B is an inherited X-linked recessive disease that results in the deficiency of functional Factor IX (FIX), which is a plasma clotting factor in the intrinsic pathway of the coagulation cascade. There are many polymorphisms of the FIX gene mutation, but the most common causes of Hemophilia B are due to point mutations and deletions. If there is not enough functional FIX, then our intrinsic coagulation pathway can’t do its job, which increases our propensity for bleeding. For a more detailed discussion of coagulation, I highly recommend Dr. Krafts’ excellent book “Clot or Bleed, A Painless Guide for People Who Hate Coag.”

What pattern of bleeding do we expect to see in patients with Hemophilia B? Since Hemophilia B is a deficiency in coagulation, and NOT platelet plug formation, we would NOT expect to see an increased bleeding time, but rather:

  • increased rebleeding
  • bleeding into joints
  • heavier physiological bleeding

Let’s look at each of these.

Increased rebleeding
While the formation of the platelet plug temporarily stops the bleeding, it is the coagulation cascade that turns the plug into a hard clot to prevent the reopening of the injury site. If the hard clot cannot form, then a small disturbance in the plug could break it and cause the injury site to open up and bleed again. An example of this is would be a difficult-to-control epistaxis. When the patient gets a nosebleed, he could squeeze his nose to stop the bleeding. The manual compression gives platelets a chance to plug up the damaged tissue. However, since the platelet plug cannot transform into a hard clot, when the patient disturbs his nasal mucosa shortly thereafter, such as blowing his nose, rubbing it, or even breathing hard, the movement could bust the platelet plug open, thereby allowing the bleeding to restart.

Bleeding into joints
The synovial cells that line our joints naturally synthesize high levels of coagulation inhibitors to prevent the joint from getting clotted up, thus losing its mobility, when small bleeds happen in the joint. In normal patients, this wouldn’t be a problem since the bleeding would bring more blood, and thus more clotting factors, to the injury site, and that would create enough hemostasis to stop the bleeding. However, in Hemophilia B patients, the high levels of localized coagulation inhibitors combined with the systemic deficiency of FIX throw the local hemostasis out of whack, allowing continuous hemorrhage into the joint. Hemarthrosis is quite debilitating since it is very painful, and it can lead to chronic inflammation and deterioration of the joint, resulting in permanent loss of mobility and deformities.

Heavier physiological bleeding
In the rare case that the patient is female, menorrhagia is a common occurrence. During menses, bleeding wanes because of the coagulation cascade hardening all the platelet plugs that form in the uterus, thus securely stopping the bleeding. However, if clots cannot form, then the platelet plugs keep opening up, allowing bleeding to continue. 

Let’s conclude by looking at what typically brings a patient with Hemophilia B into the office. Since this is an X-linked recessive disease, the typical patient would be a young boy. Babies typically present with bleeding that won’t stop after medical events such as phlebotomy, immunizations, and circumcisions. Toddlers generally present with heavy oral bleeding after teething or large hematomas from trauma when toddling around. Finally, older children usually present with heavy gum bleeding after teeth cleaning, uncontrolled epistaxis, or hemarthrosis from impact sports injuries.