April 17 is World Hemophilia Day, designated and celebrated by the World Federation of Hemophilia to spread awareness and bring the hemophilia community together.¹ Hemophilia, a rare bleeding disorder, affects the blood’s ability to clot. If not properly detected and managed, hemophilia can have dangerous and life-threatening complications, including internal bleeding and infection.²

Hemophilia is generally an inherited disorder. If patients are concerned that they may be hemophilia carriers or that their child may have hemophilia, here are some of the basics clinicians can break down for them.

Types of Hemophilia

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The type of hemophilia is determined by which clotting factor is being produced at insufficient levels. There are several types of hemophilia, and the more common variants include these:

  • Hemophilia A. Also known as classic hemophilia, hemophilia A is caused by factor VIII deficiency. It is estimated that 12 of every 100,000 men and boys in the US have hemophilia A.³ Although hemophilia A is often passed down from parent to child, it can develop without a family history. Approximately 60% of hemophilia A cases are considered severe.
  • Hemophilia B. Hemophilia B, also known as Christmas disease, is caused by a deficiency of factor IX. It is a less common variant than hemophilia A, occurring in an estimated 3.7 of every 100,000 men and boys in the US.⁴
  • Hemophilia C. Caused by factor XI deficiency, hemophilia C is also known as plasma thromboplastin antecedent deficiency. This rare diagnosis is estimated to occur in 1 of every 100,000 people.⁵

How is Hemophilia Inherited?

Hemophilia is often inherited. According to the US Centers for Disease Control and Prevention (CDC), the X chromosome has the genes that can have mutations that cause hemophilia.⁶ If a father (XY chromosomes) does not have hemophilia but a mother (XX chromosomes) carries a hemophilia gene, a child with XY chromosomes would have a 50% chance of inheriting hemophilia while a child with XX chromosomes has a 50% chance of being a carrier of the hemophilia gene.

People with XX chromosomes can have hemophilia, but this is a rare occurrence that is only possible if both inherited XX chromosomes are affected.

Hemophilia is not always an inherited disorder. Approximately one-third of hemophilia patients are the first in their family to have the gene mutation.

Signs and Symptoms of Hemophilia

Of course, a positive test result for hemophilia is one sign of the disease. Symptoms for hemophilia include the following:

  • Blood in the urine and stool
  • Pain, tightness, swelling, and bleeding in joints
  • Bleeding in the mouth and gums
  • Bleeding after vaccinations
  • Large, deep bruises
  • In neonates, bleeding after circumcision or bleeding of the head after a difficult delivery
  • Unexplained, hard-to-stop nosebleeds

Diagnosing Hemophilia

If a child is genetically at risk for hemophilia, testing is often planned for soon after birth using a blood sample from the neonate or from the umbilical cord.⁷ Blood screening and clotting factor tests will need to be conducted to determine both the severity of the hemophilia and the specific factor deficiency. For example, the activated partial thromboplastin time test, which measures how long clotting takes, tests for deficiencies in factors VIII, IX, XI, and XII.

Hemophilia Treatment

Clotting factor replacement therapy, the injection of clotting factor concentrates into a patient’s vein, is a common form of treatment for hemophilia.⁸ These injections can be done at home on a regular schedule to manage bleeding episodes and avoid complications.

Patients with mild hemophilia may use desmopressin, a medication similar to a natural hormone, which can release factor VIII from patients’ own body tissues. It is available both as an injection and a nasal spray.


  1. World Hemophilia Day 2021. World Federation of Hemophilia. https://www.wfh.org/en/events/world-hemophilia-day. Accessed April 8, 2021.
  2. Hemophilia – symptoms and causes. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/hemophilia/symptoms-causes/syc-20373327. Accessed April 8, 2021.
  3. Hemophilia A. National Hemophilia Foundation. https://www.hemophilia.org/bleeding-disorders-a-z/types/hemophilia-a. Accessed April 8, 2021.
  4. Hemophilia: a new study of hemophilia occurrence finds many more cases in the United States. US Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/hemophilia/features/keyfinding-hemophilia-occurrence-US.html. Reviewed July 17, 2020. Accessed April 12, 2021.
  5. Factor XI. National Hemophilia Foundation. https://www.hemophilia.org/bleeding-disorders-a-z/types/other-factor-deficiencies/factor-xi. Accessed April 8, 2021.
  6. What is hemophilia? US Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/hemophilia/facts.html. Reviewed July 17, 2020. Accessed April 8, 2021.
  7. Hemophilia: diagnosis. US Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/hemophilia/diagnosis.html. Reviewed July 17, 2020. Accessed April 8, 2021.
  8. Hemophilia: treatment. US Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/hemophilia/treatment.html. Reviewed July 17, 2020. Accessed April 8, 2021.