What Is Factor V Deficiency?

Factor V (proaccelerin) deficiency is an inherited bleeding caused by a defect or lack of a protein in the blood (factor V) that helps blood clot. It is very rare, and affects one in 1,000,000 people. It is passed from parent to child and is an autosomal recessive disorder, meaning that both parents must carry the defective gene in order to pass it on to their child and that it affects both males and females. The gene is found on chromosome 1.

Symptoms

People with factor V deficiency may experience:

nose bleeds
easy bruising
heavy or prolonged menstrual bleeding (menorrhagia)
bleeding after trauma (injury)
abnormal bleeding after surgery
joint and muscle bleeding (in people with severe factor V deficiency)

Children with severe deficiency may bleed very early, and the development of antibodies to factor V seems to be more common.
In most cases, a factor V level at 20% of normal is enough to prevent bleeding even after surgery.

Diagnosis

Factor V deficiency is diagnosed by a variety of blood tests to see if there is a bleeding disorder and, if so, to determine which one it is. Factor VIII should also be tested to make sure that the disorder is not combined factor V and factor VIII deficiency, which is a completely separate disorder.

Treatment

Factor V deficiency is treated with:

fresh frozen plasma (FFP)
factor VIIa concentrates

Content reviewed by Dr. Paula Bolton-Maggs
Consultant Haemotologist
Manchester Haemophilia Comprehensive Care
Manchester Royal Infirmary
Manchester, UK.

Last updated December 2007