I'm so sorry for your loss and your incredible PE history.
I have MTHFR gene mutation. However, about 30% of the human population has this mutation. The current consensus in literature suggests it plays little in the role of preeclampsia with respect to the kind of clot formed. Plus, if this gene is present in 30% of the population, we would expect to hear more stories like ours.
MTHFR affects the homocysteine levels in your blood, which in turn affects folic acid uptake, which in turn could possibly thicken blood making your more susceptible to blood clotting. But as you can see, it's more of a secondary or tertiary effect.
I am taking 1mg Folic Acid 4x/day to help offset MTHFR, and 1 tablet Low Dose Aspirin (81mg). The thought is that the baby aspirin helps keep the blood more fluid and less thick so it less likely to form clots.
Take a gander at this. I think the text is better at explaining it than the video. So I suggest you read before watching the video. This was a meta-analysis by the journal of obgyn last july 2010...so a pretty recent study, that's well done.http://www.thedoctorschannel.com/video/3510.html