 The major ( " type 1 " ) thrombophilias are rare . Antithrombin deficiency is present in 0 @.@ 2 % of the general population and 0 @.@ 5 – 7 @.@ 5 % of people with venous thrombosis . Protein C deficiency , too , is present in 0 @.@ 2 % of the population , and can be found in 2 @.@ 5 – 6 % of people with thrombosis . The exact prevalence of protein S deficiency in the population is unknown ; it is found 1 @.@ 3 – 5 % of people with thrombosis . 
