THE FAMILY HISTORY AND INHERITED THROMBOPHILIA

The role of the family history as a tool for the diagnosis of inherite d thrombophilia has not been established. Several authors have indicat ed that a positive family history is not a good predictor of inherited abnormalities such as antithrombin m deficiency, or deficiencies of p rotein C or protein S. We have tried to approach the family history in a quantitative way. To this end we used the cumulative incidence data of thrombosis in the general population and also in a population of p rotein C deficient families to estimate the expected number of symptom atic subjects in a family under both the hypothesis of inherited throm bophilia and the null-hypothesis. Although a number of assumptions und erlying our calculations need to be verified and probably adjusted bef ore any truly quantitative meaning can be assigned to this approach, w e feel that the family history is a useful diagnostic test for inherit ed thrombophilia if it is used in a critical way.