What Is The Difference Between Heterozygous And Homozygous?

DNA Strands

Factor V Leiden Genetic Mutations

Genetic mutations take on multiple forms and in this case we're looking at the types of Factor V Leiden and what the differences between Heterozygous and Homozygous actually mean for someone with the mutation.

What Is Factor V Leiden

Factor V Leiden is a genetic mutation in one of the proteins that forms clots. In a person with a normal Factor V protein the "off switch" call Activated Protein C tells the protein to stop working which prevents the clot from getting bigger. However, with someone with Factor V Leiden (the abnormal version) the Activated Protein C "switch" cannot communicate with the protein to switch it off which can cause clots to get bigger and then break off causing a Deep Vein Thrombosis (DVT) or Pulmonary Embolisms (PE). 

How Do You Inherit Factor V Leiden

Every one inherits two copies of the Factor V gene; one from your mother and the other from your father. You will only inherit the abnormal version of the gene if at least one of your parents also has this gene, otherwise you will get the normal Factor V structure.

Inheriting a faulty gene is a fairly common event (for a genetic mutation) and for most people they will not experience any problems throughout the majority of their life. As you become older, as with nearly every other condition or disease, you will have a greater risk of getting a blood clot and will need treatment.

The highest concentration of people with a Factor V defect are in Europe with approximately 10-15% of the population being effected. In a study published in the paper "Genetics in Medicine" the prevalence of American people discovered to have a mutation was indicative of a worldwide population spread:

• 5.2% of white Americans
• 2.2% of Hispanic Americans
• 1.2% of African Americans
• 0.45% of Asian Americans
• 1.25% of native Americans

As you can see by the figures there is a very small chance of you inheriting the mutation.

Are You Heterozygous Or Homozygous?

There are only three versions of the Factor V gene that you can inherit:

• Normal: both copies of the gene function as they should
• Heterozygous: one copy of the gene is normal and one has the mutation
• Homozygous: both copies of the gene have the mutation

Heterozygous Risks

If you are diagnosed as having one copy of the mutated gene then are at a higher risk for a blood clot but you can change your lifestyle to lower the chances of getting a blood clot. Taking action with weight management, quit smoking, and staying active are good examples of improving your lifestyle.

If you are unfortunate to suffer a blood clot the you will need to go on to a blood thinner such as Warfarin or other anti-coagulant; this may be for life or for a shorter duration but your doctor will let you know.

Homozygous Risks

The possibility of getting to mutated genes is approximately 1% of the Heterozygous chance; if you are Caucasian and have a 5% chance of getting a faulty gene then you will have a 1% of 5% chance (fewer than 1 in 100 people) of getting both faulty genes.

As with Heterozygous genes you will only need treatment if you have experienced a clot and you are healthy in all other areas. If you are at risk with other factors then your doctor may put you on blood thinners as a preemptive measure.