Hemophilia: Genetic Testing and What to Expect

Though hemophilia is considered as a rare genetic blood disorder, it affects more men than women worldwide, with around 1,125,000 men affected. The frequency of hemophilia in women is yet unknown and needs further investigation.

One of the genes that produces the proteins known as clotting factors, which are responsible for stopping bleeding, genetic mutations in hemophilia, which affects blood clotting properly and causes spontaneous bleeding, especially after exposure to injuries or surgical procedures, which can result in complications that could be fatal.


We will learn more about hemophilia, its types, potential therapies, the use of genetic testing in the early detection of hemophilia, and its involvement in the development of novel, more potent medications in this article.

Causes of hemophilia

Hemophilia occurs due to a mutation in the genes responsible for producing proteins that clot the blood in case of bleeding, also known as clotting factors.

These genes are located on the X chromosome, of which males have two copies (XX), so a mutation in one copy of this chromosome is sufficient to cause hemophilia and its symptoms in males. Females, on the other hand, have only one copy of the X chromosome (XY), so if any mutation occurs in the genes responsible for producing blood clotting proteins on the X chromosome, they become carriers of the disease without displaying symptoms. The likelihood of passing it on to their offspring increases, explaining the higher incidence of hemophilia in males than in females.

Types of hemophilia

There are different types of hemophilia, but the most common are:

• Hemophilia A: It occurs as a result of a change in the F8 gene responsible for the production of clotting factor VIII. It is the most common type of hemophilia and is also known as (classic or classical hemophilia).
• Hemophilia B: It occurs as a result of a change in the F9 gene responsible for the production of clotting factor IX, and is also known as (Christmas disease).

There is also a third type of hemophilia called “Hemophilia C,” which is a very rare type that affects about 1 in 100,000 people around the world and is caused by a change in the F11 gene responsible for the production of clotting factor 11 (XI).

Symptoms of hemophilia

• Bleeding in the joints (elbows, knees, ankles) and may be accompanied by pain or swelling.
• Bleeding into the skin, muscles and tissues and appears in the form of bruises.
• Bleeding in the mouth and gums, which is difficult to stop in the case of wounds or tooth loss.
• Nosebleeds that are frequent and difficult to stop.
• Bleeding in urine or stool.
• Bleeding after receiving vaccinations or undergoing surgery.

Hemophilia may result in other complications, such as:

• Chronic joint diseases resulting from joint bleeding.
• Convulsions or paralysis as a result of head or brain bleeding.
• Death if the bleeding is not stopped, especially if it is in a vital organ such as the brain.

Is There a Treatment for Hemophilia?

Bleeding caused by hemophilia can be stopped by replacing the missing clotting factor or compensating for the deficient amount of it with another synthetic clotting factor through intravenous injection, which the patient can administer themselves.

Hemophilia and Gene Therapy

The FDA recently approved two new drugs for hemophilia A and B. Both drugs rely on gene therapy technology, where a new copy of the gene with the mutation causing hemophilia is added to liver cells (which produce clotting factors in the blood) using a viral vector to stimulate them to produce a new clotting factor instead of the missing one.

Research is ongoing regarding the potential use of gene editing technology to modify DNA to restore the gene to its function in producing clotting factor.

Hemophilia and the Importance of Genetic Testing in Early Diagnosis and Treatment

Genetic testing significantly contributes to:

Early Diagnosis

Genetic testing helps identify the genetic causes of hemophilia early through premarital and prenatal genetic screenings, exome sequencing, and comprehensive genetic testing (genome) to determine whether couples carry any genetic changes causing hemophilia for their future children and provide necessary recommendations.

Genetic testing can also be performed for newborns to confirm their diagnosis of hemophilia and determine its type, as approximately one-third of infants diagnosed with hemophilia carry new genetic changes causing hemophilia different from those present in their families. Genetic tests also help hemophilia patients determine the likelihood of developing inhibitors that affect blood clotting during bleeding, altering the healthcare plan provided to them.

Family Planning

Genetic testing enables prospective couples and married individuals to detect genetic changes that may cause hemophilia in their future children through premarital and prenatal genetic screenings or carrier screening to determine whether couples carry any genetic changes causing hemophilia for their future children, along with providing necessary recommendations. This may include genetic testing for the wife's family as well to ensure they are not carriers of genetic changes causing hemophilia, to provide necessary recommendations and available options for childbirth.

Development of New Treatments

Genetic testing allows for the discovery of additional genes with mutations leading to hemophilia or the discovery of other unknown types of hemophilia, to gain a more comprehensive understanding of how these changes contribute to hemophilia and to develop more effective treatment options.

Genetic Counseling

Genetic counseling guides appropriate actions and recommends comprehensive genetic testing based on the information provided about your health condition and that of your family. Genetic counseling also helps determine the frequency of hemophilia occurrence in the family based on kinship. The role of the genetic counselor is not limited to pre-testing only, but also helps you understand the test results to provide you with necessary recommendations and guidance and offer the necessary psychological support.

Enigma Genomics provides comprehensive genetic tests for hereditary diseases, such as premarital screening, which covers more than 550 hereditary diseases, Whole Genome Sequencing, which covers more than 7,500, and Whole Exome Sequencing, which covers 7,000 genetic diseases and others to help you in the journey of maintaining your health and the health of your family.