Combined factor V (pronounced factor 5) and factor VIII (pronounced factor 8) deficiency is a very rare inherited bleeding disorder.
Both factor V and factor VIII are proteins in the blood. They both play a role in the coagulation cascade, the chain reaction that is set in motion when there is an injury to a blood vessel.
With this disorder, the levels of factor V and factor VIII in the blood are lower than normal. Blood tests measure the levels at between 5% and 30% of normal.
For more information on blood clotting, see The clotting problem in Hemophilia.
Combined factor V and factor VIII deficiency is very rare. Altogether less than 100 people in 60 families have been identified in the world to date.
It is seen throughout the world. However, most of the cases have been found around the Mediterranean Sea, especially in Israel, Iran and Italy. It is thought that in some populations, 1 in 100,000 people could be affected. While still rare, this makes the factor V and factor VIII Deficiency the most common combined factor deficiency.
Combined factor V and factor VIII deficiency is an hereditary disease. This means that it is passed on from the parents to the child at the time of conception. It is caused by a gene defect on chromosome 18.
It is an ‘autosomal recessive’ disorder. This means that both parents must carry the defective gene to be able to pass it on to their children. When only one parent has the gene which causes the disorder, the child, is not affected. Combined factor V and VIII deficiency affects males and females in equal numbers.
In extremely rare cases, a deficiency in factors V and VIII could have a different cause. Instead of a single defective factor V-VIII gene on chromosome 18, a child could inherit a defective factor V gene from both parents and a defective factor VIII gene from one parent. The chances of inheriting factor V Deficiency are 1 in 1,000,000 and the chances of inheriting factor VIII are 1 in 10,000. Therefore, the chances of inheriting both defective genes separately are 1 in 10 billion.
The factor VIII levels in this disorder are usually between 5% and 30%. In factor VIII deficiency (Hemophilia A) alone, this level would give mild bleeding symptoms. However, the additional problem of low factor V levels seems to cause more bleeding.
Common symptoms are:
- nose bleeds
- easy bruising
- heavy or prolonged menstrual bleeding (menorrhagia)
- bleeding after giving birth
- bleeding after trauma (an injury)
- bleeding after surgery.
If a bleeding disorder is suspected, doctors will do a number of tests to find out:
- if the person has a bleeding disorder and
- if so, what particular bleeding disorder it is.
Combined factor V and factor VIII deficiency is diagnosed if:
- the level of factor V is less than 30% of normal
- the level of factor VIII is less than 30% of normal
- the partial thromboplastin time is prolonged.