Advancing basic and clinical knowledge about thrombosis is the major goal of this Project. Excessive thrombin generation causes thrombosis, including venous thromboembolism (VTE) which is a complex disease. Genomics-based research should be a powerful tool for discovery of VTE risk factors, but GWAS had added few new insights. In contrast to GWAS that is centered on common gene variations, new exome genotyping arrays permit interrogation of rare functional variants throughout the genome. Race-specific causal factors for VTE in Caucasian, Japanese and Chinese populations involve rare variants in coagulation proteins. The missing heritability of VTE risk may be attributed, in part, to rare or low frequency variants. Exome genotyping can interrogate > 250,000 variations for rare missense variants that might alter a protein's functional activity. Our initial application of exome array technology to one cohort of European Americans and one cohort of African Americans yielded surprising findings which will be confirmed and extended by this project. While identification of new genetic variants linked to VTE represents significant and valuable genetic associations, it is critical to determine whether and how the biological activities of the newly implicated candidate gene's product may contribute to thrombosis. Our initial exome genotyping implicated certain structural protein genes as being linked to VTE risk, including some myosin heavy chain genes. This surprising discovery led to the discovery that some myosins have procoagulant activity. We propose to characterize the mechanisms by which myosin promotes thrombin generation by its interactions with clotting factors. We also propose to clarify mechanisms by which the constitutive plasma protein, serum amyloid A 4, interacts with clotting factors to promote thrombin generation. A major goal of this project is to discover new genetic rare variants that are linked to VTE among the understudied African American population for whom no genetic risk factor has yet been widely recognized. Our initial exome genotyping data significantly identified a set of VTE- linked rare variants unique to African Americans and another set of VTE-linked rare variants unique to Caucasian Americans. For this project, we propose to study seven cohorts from key collaborating centers wherein these studies will include circa 3,000 Caucasians and 2,000 African Americans. These cohorts will enable replication of our initial exome genotyping-based discoveries and will facilitate efforts for further discoveries of exomic rare variants linked to VTE. If successful, new knowledge from this project will include discovery of thrombosis-related rare genetic variants and revelation of new proteins that may contribute to thrombosis risks. This new knowledge about new genes and previously unrecognized proteins will significantly extend our concepts about VTE pathophysiology and will have potential implications for new diagnostic or therapeutic applications.

Public Health Relevance

Excessive, uncontrolled blood clotting causes life-threatening thrombosis, including venous thrombosis in the legs or lungs. The proposed studies of blood proteins and of rare genetic variations in African American patients and in Caucasian patients will discover new risk factors for venous blood clots. The new knowledge coming from this study will provide new basic and clinical knowledge that will hopefully improve diagnosis and treatment of bleeding and of thrombosis.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
Project #
Application #
Study Section
Hemostasis and Thrombosis Study Section (HT)
Program Officer
Ochocinska, Margaret J
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Scripps Research Institute
La Jolla
United States
Zip Code
Martos, Laura; Ramón, Luis Andrés; Oto, Julia et al. (2018) ?2-Macroglobulin Is a Significant In Vivo Inhibitor of Activated Protein C and Low APC:?2M Levels Are Associated with Venous Thromboembolism. Thromb Haemost 118:630-638
Healy, Laura D; Rigg, Rachel A; Griffin, John H et al. (2018) Regulation of immune cell signaling by activated protein C. J Leukoc Biol :
Griffin, John H; Zlokovic, Berislav V; Mosnier, Laurent O (2018) Activated protein C, protease activated receptor 1, and neuroprotection. Blood 132:159-169
Sinha, Ranjeet K; Wang, Yaoming; Zhao, Zhen et al. (2018) PAR1 biased signaling is required for activated protein C in vivo benefits in sepsis and stroke. Blood 131:1163-1171
Deguchi, Hiroshi; Elias, Darlene J; Griffin, John H (2017) Minor Plasma Lipids Modulate Clotting Factor Activities and May Affect Thrombosis Risk. Res Pract Thromb Haemost 1:93-102
Deguchi, Hiroshi; Navarro, Silvia; Payne, Amanda B et al. (2017) Low level of the plasma sphingolipid, glucosylceramide, is associated with thrombotic diseases. Res Pract Thromb Haemost 1:33-40
Deguchi, Hiroshi; Sinha, Ranjeet K; Marchese, Patrizia et al. (2016) Prothrombotic skeletal muscle myosin directly enhances prothrombin activation by binding factors Xa and Va. Blood 128:1870-1878