Is factor XII activity measured by clotting test a useful screening parameter for HAE-FXII?

Introduction Hereditary Angioedema is a rare condition characterized by recurrent swellings of the skin, mucosa or the intestines caused by uncontrolled generation of bradykinin. There are three types of HAE. Type III is mostly caused by a gain-of-function mutation in the factor XII (FXII) gene, which leads to increased activation of the kinin-kallikrein-system and therefore bradykinin overproduction. In the clinical routine FXII is measured using the clotting test, as the amidolytic test mentioned in the original publication is not available up until now.

The study at hand aims to determine whether the clotting test can identify patients suffering of HAE with FXII gene mutation (HAE-FXII).

Material and Methods All patients who had been diagnosed with HAE-FXII at our clinic were included in this study. They were compared to a control group, presenting to our out-patient clinic with swellings of non-hereditary genesis. Plasma FXII activity was measured using a FXII clotting test in both groups.

Results We included four patients with HAE-FXII and 100 control patients. The average FXII activity within the HAE-FXII group was 109 % (+/-13), compared to 107 % (+/- 26) within the control group. There was no significant difference between both study groups (p > 0,4).

Conclusion There is no significant difference in FXII activity between the two groups. Therefore, FXII clotting test does not help to identify patients with HAE-FXII. When HAE-FXII is suspected molecular genetic testing should be performed regardless of FXII activity.

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Artikel online veröffentlicht:
10. Juni 2020