Coincidence of hereditary angioedema (HAE) with Crohn's disease

A patient with two diseases, based presumably on different immunopathologic al mechanisms, hereditary angioedema (HAE) and Crohn's disease, was followe d for 8 years. For more than three years of this observation period, detail ed laboratory data were also available and could be analyzed. Both diseases had severe courses requiring chronic treatment with danazol and sulfasalaz ine, respectively. During exacerbation of Crohn's disease, the levels of C4 was found to be significantly lower than during the periods free of sympto ms of both diseases. This drop was probably due to an impaired C1-inhibitor activity. HAE attacks and acute exacerbation of Crohn's disease never occu rred simultaneously. This finding may be a mere chance but may also indicat e that the different immunopathological processes underlying HAE and Crohn' s disease influence each other.