A 2 year old male was brought into the pediatrician’s office by his mother after tripping over a toy truck 2 days earlier. The mother stated that the child cut the inside of his lip in the fall, and the lip had been oozing blood for the past 2 days. The child had also experienced a bloody nose several times since the fall. Upon examination, the child appeared in general good health with no other bruising or bleeding. Examination of the joints revealed swelling in the right knee. The physician took a family history, and the mother reported that her younger brother has ‘some sort of bleeding problem’ and experienced prolonged bleeding after a tonsillectomy as a child, and after several surgeries as a young adult. The physician ordered blood work on the child.
- Hgb 9.5 g/dl
- Hct 30%
- Platelet 185 x 103/ uL
- INR 1.1
- aPTT 57 sec
- Mixing Test: corrected
- Thrombin Time: normal
Based on these results, the prolonged aPTT warranted further investigation. A differential diagnosis involved ruling out other causes for the prolonged aPTT. The physician ordered mixing studies, factor VIII and factor IX assays and vWF. Mixing studies are used to determine if etiology of prolonged PT or PTT is due to a factor deficiency or an inhibitor. If the aPTT remains prolonged after mixing with normal plasma, this indicates an inhibitor. If the prolonged PTT becomes normal after the mixing studies, this would indicate a factor deficiency. The factor VIII and vWF were normal, but factor IX activity was 25%. Diagnosis: Factor IX deficiency. (It was also confirmed, after speaking with the child’s uncle, that he also had a factor IX deficiency)
So, you may ask, what does this have to do with Christmas? In the spirit of the season, I chose to present a Case Study on Factor IX deficiency, aka Christmas Disease. But, alas, this really has nothing to do with the holiday. Maybe it has something to do with the fact that the first article about this disorder was published in the British Medical Journal on Dec 27, 1954 (just 2 days after Christmas)? But, not so. Actually, Factor IX deficiency is also called Christmas Disease because it is named after Stephen Christmas, the first patient described to have Factor IX deficiency. Stephen Christmas was diagnosed with hemophilia in Toronto in 1949, at the age of 2. The family was visiting relatives in London in 1952 and it was there that doctors discovered that he was not deficient in Factor VIII, the cause of Classic Hemophilia as it was known at the time. It was discovered that he was deficient in another coagulation protein. This new protein was named Christmas protein and later became known as Factor IX.
A little bit more about the history of Factor IX deficiency. Before the discovery of the Christmas protein, it was thought that Hemophilia was a single disorder, caused by a deficiency of Factor VIII. With the discovery of this new protein, Classic Hemophilia (Factor VIII deficiency), was given the name Hemophilia A, and this new Factor IX deficiency became known as Hemophilia B. Yet another nickname for this disorder is the Royal Disease. Hemophilia was prominent in the European royal families in the 19rth and 20th centuries. Queen Victoria of Britain was a carrier of hemophilia and passed the gene on to three of her children. Her children and descendants married into the royal families of Germany, Russia and Spain, giving her the nickname the Grandmother of Europe. But, these marriages also served to spread the disease to these other royal houses, giving hemophilia the nickname Queen Victoria’s curse. The last known member of the royal families of Europe to carry the gene passed away in 1945, 9 years before that article in the British Medical Journal (December 27, 1954). So, how do we know that Hemophilia B is the hemophilia responsible for the Royal Disease? In 2009, DNA testing on bones identified as Anastasia and Alexei Romanov, the last Russian royal family descendants of Queen Victoria, determined that the Royal Disease was Hemophilia B.
I remember teaching Hematology and Genetics before 2009 using a pedigree chart of Queen Victoria’s family to teach students about Hemophilia as an X linked recessive disorder. We created Punnett squares that showed the inheritance from Queen Victoria to her family members and descendants across Europe. I always enjoyed this lecture, because it was a fun piece of historical trivia paired with a good science lesson. After 2009, the science of the inheritance did not change, but we now knew that this Royal Disease was Hemophilia B. Hemophilia B is caused by mutations in the F9 gene which is responsible for making the factor IX protein. The F9 gene is on the X chromosome. Hemophilia B, like Hemophilia A, is X linked, carried by the mother. 50% of males born to a carrier mother will have the disease and 50% of daughters will be carriers. All daughters of affected males will be carriers, but their sons will not be affected. Hemophilia A is more common than Hemophilia B, affecting about one in 5,000 males. Hemophilia B affects about one in 25,000 males. It has been though that up to about 30% of Hemophilia B cases occur as a spontaneous mutation and are not inherited. This has been thought to be the case with Queen Victoria. She has been believed to be ‘case zero’, the first hemophilia case in her family. However, some newer articles that have researched her family history suggest that she may have had a half-brother who had the disease.1 There are also other related disorders including a rare autoimmune acquired hemophilia B and another rare form of Hemophilia B called Hemophilia B Leyden.
The coagulation process involves many chemical reactions, from the initial event that triggers bleeding, to the formation of a clot. The sequence of events are generally depicted as a coagulation cascade to illustrate and simplify understanding of the process. The coagulation cascade is divided into 2 pathways, the intrinsic and extrinsic system, and a common pathway. This segregation of sections is not physiological, but allows for the grouping of factor defects and the interpretation of laboratory testing. Most problems with coagulation factors fall into one of three categories: a factor is not produced, there is a decreased production, or the factor is produced but not functioning properly. Hemophilia B is a factor IX deficiency. It is classified as mild, moderate or severe based upon the activity level of factor IX. In mild cases, bleeding symptoms may occur only after surgery or trauma and may not be diagnosed until later in life. In moderate and severe cases, bleeding symptoms may occur after a minor injury or even spontaneously. These moderate to severe cases are usually diagnosed at a younger age.
This child was diagnosed with Hemophilia B, based on coagulation studies, Factor IX assay results and family history. Treatment involves replacement of Factor IX to promote adequate blood clotting and prevent bleeding episodes.
- Turgeon, Mary Louise, Clinical Hematology: Theory & Procedures, 6th ed. Lippincott Williams and Wilkins, Philadelphia, 2017.
-Becky Socha, MS, MLS(ASCP)CM BB CM graduated from Merrimack College in N. Andover, Massachusetts with a BS in Medical Technology and completed her MS in Clinical Laboratory Sciences at the University of Massachusetts, Lowell. She has worked as a Medical Technologist for over 30 years. She’s worked in all areas of the clinical laboratory, but has a special interest in Hematology and Blood Banking. When she’s not busy being a mad scientist, she can be found outside riding her bicycle.