The Pathophysiology of Hemophilia

Written by Siya Vashi

In Greek, “hemo” means blood while “philia” means fondness, or tendency towards. When combined, hemophilia literally means “tendency towards blood.” Medically speaking, however, hemophilia is a hereditary disorder that involves uncontrollable bleeding.

Blood has three components: erythrocytes, leukocytes, and thrombocytes. Thrombocytes, also known as platelets, are responsible for clotting your blood after you have an injury. There are several parts that make up a thrombocyte, which are known as clotting factors. Hemophiliacs have an inactivated form of one of these factors, which means that they are unable to clot their blood properly and tend to bruise easily. Other symptoms include nosebleeds, hematomas (pool of blood outside a blood vessel), joint pain, and ecchymosis right at birth (a big bruise due to leaked blood). Fortunately, these noticeable symptoms allow many patients to be diagnosed at birth.

There are three types of hemophilia: hemophilia A (class hemophilia), hemophilia B, and hemophilia C. The symptoms remain the same, but the severity of these symptoms increases from A to C. Hemophilia C is very rare and occurs only when both parents carry the mutated gene.

As mentioned before, hemophilia is a hereditary disorder. Interestingly enough, it has nothing to do with your first 22 pairs of chromosomes, which are called your autosomal chromosomes. Hemophilia is a recessive X-linked disorder, which means the abnormality is found on an X chromosome, but the effects of it can be masked if there is a normal X chromosome alongside the mutated one. This is why only 11% of hemophiliacs receiving care are women. Think about it: women have two X chromosomes, while men only have one. If hemophilia were to be passed on by one parent to a female offspring, she would still have another normal X chromosome to mask the mutated one. Males, on the other hand, inherit only one X chromosome, and it comes from their mother. So, if the mother passed on her mutated X chromosome to the son, since he doesn’t have a backup X chromosome, the son will have hemophilia.

Although there isn’t a cure for hemophilia, there are hemophilia treatment centers (HTCs) available to administer either factor VIII to stop bleeding, non-factor injections to help clot, or an entire blood transfusion if necessary.

References

https://archive.cdc.gov/www_cdc_gov/ncbddd/hemophilia/features/women-and-hemophilia.html

https://www.pfizer.com/disease-and-conditions/hemophilia

https://evolve.elsevier.com/cs/product/9780323340137?role=student

Written by Siya Vashi from MEDILOQUY