High homocysteine levels in the blood (Vitamin B deficiency, reduced kidney, liver or thyroid function, increased blood pressure, certain drugs, and excess coffee can lead to elevated homocysteine levels)
Genetic risk factors:
F5 (Factor V) Leiden mutation (1691G>A)
F2 (Prothrombin) 20210G>A mutation
MTHFR - 677C>T and 1298A>C mutations result in increased homocysteine levels