Gene polymorphisms in GPIIIa, XRCC1, FBG, F7, MMP9, MTHFR, and SDF-1 may also contribute to thrombotic complications in patients with MPN, but not polymorphisms in HPA5, FAS, FASL, TERT, ACE, and TLR4 genes that have little to no association with thrombotic events in MPN. This evidence concerns the gene MMP9 and myeloproliferative disorder.