Prone-ness to thrombosis is called "thrombophilia" (should you wish to go Google-ing).
There are many genetic causes.
Factor V Leiden is present in about 1 in 20 europeans.
Inherited from one parent, it gives an approx
8x increased risk of thrombosis. Inherited from both parents, the risk soars to
80x.
In the UK these conditions are little known -
and rarely tested for.
My mother suffered a PE (blood clot in the lung) - ambulance and a week on Oxygen. My brother had a DVT. His (french) doctor had the tests done. And discovered Factor V Leiden.
My mother went to her doc with his results - and the doc agreed that she ought therefore to be tested (result: positive) and because of that she is not coming off anticoagulant 6 months after her PE, as had previously been decided.
Now, if it hadn't been for the brother's episode and his french tests, the NHS wouldn't have bothered to check for this condition. They hadn't at the hospital or the GP's.
If you have *any* family history of Thrombosis, especially if you are a European Caucasian, you ought to become aware of this stuff.
Take a look -
http://www.thrombosis-charity.org.uk...congenital.htm