Our finding that the same MMP3 haplotype (rs520540-A/G allele and rs679620-T/C) appeared to protect against thrombotic events (i.e., ischemic stroke) and promote bleeding events (i.e., hemorrhagic stroke) may be explained by cleavage of coagulation and fibrinolytic proteins (plasminogen, plasminogen activator inhibitor-1, fibrinogen) by MMP3. The gene discussed is SERPINE1; the disease is hemorrhagic stroke.