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Name: Elizabeth
Status: Educator
Grade:  6-8
Location: NV
Country: United States
Date: April 2005

What is factor 5 deficiency, and is it a mutation in the genes?

When you get a cut, there are many steps in the blood clotting process. You don't want your blood to clot for no reason, so there is a very complicated process with many steps to complete before the cut is sealed off. There are 12 steps in the process and they are numbered. They were named in the order in which they were discovered and don't necessarily go in order. Factor 5 is also known as Leiden. Yes, it is a mutation that can be inherited.Here is a link that will explain this more in detail.


Factor V is a protein (probably an enzyme) involved in the blood cloting mechanism. It is a less severe form of hemophilia and goes by several different names: thrombophilia, Owren's disease, Leiden's disease and parahemophilia. It is caused by the mutation of a gene located on chromosome 1, so it is not a sex-linked mutation like the hemophilia caused by Facdtor VIII deficiency. For further information do a search on Google and you'll get more than a million hits/

Ron Baker, Ph.D.

Factor V Leiden is a mutation in a gene on chromosome 1 that causes thrombophilia, an increased risk of blood clots. The normal version of the gene codes for factor V (Roman numeral 5), one of the factors involved in normal blood clotting. The Factor V Leiden mutation results in a faulty factor V molecule.

A person who is a heterozygote for the gene inherits a factor V Leiden mutation from either mother or father, and a normal gene from the other parent. A person who inherits the gene from both parents (a homozygote) has two faulty copies of the gene in every cell.

Other mutations (errors) in this gene are also known.

DNA testing can tell whether a person has one or two faulty copies of the gene.

For more information, contact a genetic counselor

( or see Gene

Clinics at or OMIM at

Sarina Kopinsky, MSc, CGC

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