Elevated thrombin generation in patients with congenital disorder of glycosylation and combined coagulation factor deficiencies

Abstract

Background Congenital disorders of glycosylation are rare inherited diseases affecting many different proteins. The lack of glycosylation notably affects the hemostatic system and leads to deficiencies of both procoagulant and anticoagulant factors. Objective To assess the hemostatic balance in patients with multiple coagulation disorders by using a thrombin generation assay. Method We performed conventional coagulation assays and a thrombin generation assay on samples from patients with congenital disorder of glycosylation. The thrombin generation assay was performed before and after activation of the protein C system by the addition of soluble thrombomodulin. Results A total of 35 patients were included: 71% and 57% had low antithrombin and factor XI levels, respectively. Protein C and protein S levels were abnormally low in 29% and 26% of the patients, respectively, whereas only 11% displayed low factor IX levels. Under baseline conditions, the thrombin generation assay revealed a significantly higher endogenous thrombin potential and thrombin peak in patients, relative to controls. After spiking with thrombomodulin, we observed impaired involvement of the protein C system. Hence, 54% of patients displayed a hypercoagulant phenotype in vitro. All the patients with a history of stroke‐like episodes or thrombosis displayed this hypercoagulant phenotype. Conclusion A thrombin generation assay revealed a hypercoagulant in vitro phenotype under baseline condition; this was accentuated by impaired involvement of the protein C system. This procoagulant phenotype may thus reflect the risk of severe vascular complications. Further research will have to determine whether the thrombin generation assay is predictive of vascular events.

Factor XII in PMM2-CDG patients: role of N-glycosylation in the secretion and function of the first element of the contact pathway

“…2c). This result suggested that the hypoglycosylated FXII form detected in plasma of PMM2-CDG patients contains one N-glycan (1 N-glycan-FXII), which is consistent with the size of an N-glycan (2 kDa) and the presence of hypoglycosylated forms of other proteins (antithrombin, FXI, transferrin) in these patients [21,22]. Moreover, these results also suggested that PMM2-CDG patients had no aglyco-FXII detectable by Western Blot in circulation (Fig.…”

“…Forty-six patients with confirmed PMM2-CDG were retrospectively recruited from 6 hospitals [Spain (2), France (2), Portugal (1), and Belgium (1)]. The clinical characteristics of the main cohort of these patients are described elsewhere [ 21 ]. Glycoforms of transferrin; antithrombin activity and FXI levels were quantified by HPLC, a chromogenic assay, and a coagulometric method, as described previously [ 22 ].…”

Factor XII in PMM2-CDG patients: role of N-glycosylation in the secretion and function of the first element of the contact pathway.

“…This treatment eliminated the heterogeneity of FXII forms in plasma of PMM2-CDG patients, but the resulting FXII without N-glycans (aglyco-FXII) was smaller than the aberrant FXII detected in plasma of patients ( Figure 2C). This result suggested that the hypoglycosylated FXII form detected in plasma of PMM2-CDG patients contains one N-glycan (1 N-glycan-FXII), which is consistent with the size of an N-glycan (2 kDa) and the presence of hypoglycosylated forms of other proteins (antithrombin, FXI, transferrin) in these patients [21] , [22]. Moreover, these results also suggested that PMM2-CDG patients had no aglyco-FXII detectable by Western Blot in circulation ( Figure 2C).…”

“…Forty-six patients with confirmed PMM2-CDG were enrolled in this study. The clinical characteristics of the main cohort of these patients are described elsewhere [21]. Glycoforms of transferrin; antithrombin activity and FXI levels were quantified by HPLC, a chromogenic assay, and a coagulometric method, as described previously [22].…”

N-Glycosylation Deficiency Reduces the Activation of Protein C and Disrupts Endothelial Barrier Integrity

“…[3][4][5][6] The hemostatic system's role in the pathophysiology of stroke-like episode has not yet been characterized, although elevated thrombin generation has been observed in patients with a history of stroke-like episode. 7 Coagulation factors-most of which are glycoproteins-are also frequently affected in CDG. The prevalence of protein C (PC) deficiency in patients with PMM2-CDG ranges from 29 to 72%.…”