Venkat, living with Hemophilia


Understanding Hemophilia

Hemophilia is a bleeding disorder caused by the body’s inability to accomplish the natural clotting process. People with hemophilia experience bleeds because there is an inadequate amount of a blood protein known as thrombin.

There are approximately 200,000 people worldwide with hemophilia A and hemophilia B. Traditional therapies may temporarily allow the body to produce enough thrombin to support clotting.

Clotting and thrombin

Clotting starts when platelets in blood collect at the site of injury to begin the healing process. Thrombin is critical to clotting and sealing the wound. It converts fibrinogen into fibrin, establishing a network to help more platelets accumulate.

Relative thrombin levels(%) in hemophilia

The severity of hemophila is associated with how much thrombin a person can make. As shown on the left, individuals with 100% thrombin demonstrate no symptoms of hemophilia. To get more info, including how antithrombin may play a role, see the Hemophilia Brochure below.

Learn more about Hemophilia

Download the Alnylam Hemophilia Brochure.

Meet Venkat

“It’s really, really tough. It gets tougher and tougher day by day; year by year.”

This is Venkat’s story about living with hemophilia.

Venkat – Living with Hemophilia


Interested in learning about our hemophilia studies? Get started here.

Learn More >


At Alnylam, we put you at the center of everything we do. We have a team dedicated to collaborating with patient advocacy groups and individuals affected by these rare diseases.

Read More >


  1. Srivastava A, Brewer AK, Mauser-Bunschoten EP, et al. Guidelines for the management of hemophilia. Haemophilia. 2013;19:e1-47.
  2. Dargaud Y, Béguin S, Lienhart A, et al. Evaluation of thrombin generating capacity in plasma from patients with haemophilia A and B. Thromb Haemost. 2005;93:475-480.
  3. Momin TA, Macsata RA, Sidawy AN. Thrombogenesis and Thrombolysis. In: Ascher E, ed. Haimovici’s Vascular Surgery. 6th ed. Oxford, UK: Wiley-Blackwell; 2012:209-220.
  4. Ragni MV. Targeting antithrombin to treat hemophilia. N Engl J Med. 2015;373(4):389-391.
  5. Shetty S, Vora S, Kulkarni B, et al. Contribution of natural anticoagulant and fibrinolytic factors in modulating the clinical severity of haemophilia patients. Br J Haematol. 2007;138:541-544.
  6. Ragni MV, et al. Presentation at: American Society of Hematology; December 4, 2016; San Diego, California.
  7. Pasi KJ, et al. Presentation at: American Society of Hematology; December 3, 2016; San Diego, California.
  8. Clark DP. Protein synthesis. In: Molecular Biology, Academic Cell Update Edition. Burlington, MA: Academic Press; 2009:197-233.
  9. Wittrup A, Lieberman J. Nat Rev Genet. 2015;16:543-552.
  10. Napoli C, Lemieux C, Jorgensen R. Plant Cell. 1990;2(4):279-289.
  11. Fire A, Xu S, Montgomery MK, Kostas SA, Driver SE, Mello CC. Nature. 1998;391(6669):806-811.


Receive updates on our investigational therapies and clinical trials.