Congenital blood coagulation factor XIII deficiency and perinatal management.

Transglutaminases are at least 9 enzymes which cross-link a number of proteins. This type of reaction not only enhances the original functions of substrate proteins, but also adds new functions to them. Factor XIII (FXIII) is a plasma transglutaminase circulating in blood as a heterotetramer and consisting of two catalytic A subunits and two non-catalytic B subunits. It is a proenzyme activated by thrombin in the blood coagulation cascade. It plays an important role(s) in hemostasis, wound healing, and maintenance of pregnancy. Accordingly, a lifelong bleeding tendency as well as abnormal wound healing and recurrent spontaneous miscarriage are common symptoms of FXIII deficiency. Genetic and molecular mechanisms of congenital deficiencies have been analyzed in vitro. The mechanisms of these defects have also been studied in detail by using FXIII gene knock-out mice in vivo. We analyzed eight successful outcomes of pregnancy in patients with congenital deficiency of FXIIIA, in which the plasmatic level of maternal FXIIIA and/or the precise substitute therapies were mentioned. Then we propose the following guidelines for the perinatal management: (i) decidual bleeding usually begins from 5 weeks of gestation and spontaneous abortion always occurs subsequently without substitute therapy; (ii) the plasma level of FXIIIA must be at least 2 approximately 3%, however, if possible, higher than 10% to prevent bleeding and miscarriage; (iii) the administration of 250 IU of FXIIIA concentrate each 7 days is enough to keep the level of plasma FXIIIA more than 10% in the early gestation, however 500 IU each 7 days is adequate in the later period to keep that level; (iv) during labor, the desired level is higher than 20%, if possible, higher than 30% to avoid any risk of strong obstetrical bleeding.