“Prothrombin deficiency is a disorder caused by a lack of a protein in the blood called prothrombin. It leads to problems with blood clotting (coagulation). Prothrombin is also known as factor II (factor two).

When you bleed, a series of reactions take place in the body that helps blood clots form. This process is called the coagulation cascade. It involves special proteins called coagulation, or clotting, factors. You may have a higher chance of excess bleeding if one or more of these factors are missing or are not functioning like they should.

Prothrombin, or factor II, is one such coagulation factor. Prothrombin deficiency runs in families (inherited) and is very rare. Both parents must have the gene to pass the disorder on to their children. A family history of a bleeding disorder can be a risk factor.

Prothrombin deficiency can also be due to another condition or use of certain medicines. This is called acquired prothrombin deficiency.”

Mount Sinai  (https://www.mountsinai.org/health-library/diseases-conditions/factor-ii-deficiency)