Abstract
Introduction: Prothrombin deficiency is a very rare disorder caused by mutations in the F2 gene that generate hypoprothrombinemia or dysprothrombinemia and is characterized by bleeding manifestations that can vary from clinically irrelevant to life-threatening. Aim: Here we characterize a patient with a novel missense mutation in F2, c.1090 T/A (p. Val322Glu), that causes severe dysprothrombinemia. Methods: Coagulation assays, prothrombin Western Blotting, FII activation by Ecarin, fibrinogen degradation products quantification and thrombin generation assay were carried out to assess prothrombin expression and function. PCR followed by direct sequencing was carried out to characterize the mutation. In silico analysis for missense variant and molecular modeling were applied to predict the mechanism that leads to dysprothrombinemia. Results and conclusions: The homozygous patient had a markedly prolonged prothrombin time, strongly reduced FII activity (0.82%) but normal antigen levels. In the thrombin generation assay the lag time and the peak height were unmeasurable, suggesting that the Val322Glu mutation results in the inability of the mutant prothrombin to be fully activated to thrombin. In fact, prothrombin activation by ecarin was defective, with a massive accumulation of the meizothrombin intermediate. Molecular modeling and dynamic simulation studies showed that the Val322Glu mutation interferes with protein flexibility at Arg271 and Arg320. This impairs the switch of the protein from zymogen to proteinase, thus preventing the formation of thrombin. Accumulated meizothrombin, however, maintains some fibrinogen-degrading activity, as shown by the formation of FDPs, and this probably explains the patient's mild bleeding phenotype.
| Original language | English |
|---|---|
| Pages (from-to) | 1135-1141 |
| Number of pages | 7 |
| Journal | Thrombosis Research |
| Volume | 134 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 2014 |
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Keywords
- Dysprothrombinemia
- Factor II
- Meizothrombin
- Molecular modeling
- Prothrombin activation
ASJC Scopus subject areas
- Hematology
- Medicine(all)
Cite this
A novel congenital dysprothrombinemia leading to defective prothrombin maturation. / Bafunno, Valeria; Bury, Loredana; Tiscia, Giovanni Luca; Fierro, Tiziana; Favuzzi, Giovanni; Caliandro, Rocco; Sessa, Francesco; Grandone, Elvira; Margaglione, Maurizio; Gresele, Paolo.
In: Thrombosis Research, Vol. 134, No. 5, 2014, p. 1135-1141.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A novel congenital dysprothrombinemia leading to defective prothrombin maturation
AU - Bafunno, Valeria
AU - Bury, Loredana
AU - Tiscia, Giovanni Luca
AU - Fierro, Tiziana
AU - Favuzzi, Giovanni
AU - Caliandro, Rocco
AU - Sessa, Francesco
AU - Grandone, Elvira
AU - Margaglione, Maurizio
AU - Gresele, Paolo
PY - 2014
Y1 - 2014
N2 - Introduction: Prothrombin deficiency is a very rare disorder caused by mutations in the F2 gene that generate hypoprothrombinemia or dysprothrombinemia and is characterized by bleeding manifestations that can vary from clinically irrelevant to life-threatening. Aim: Here we characterize a patient with a novel missense mutation in F2, c.1090 T/A (p. Val322Glu), that causes severe dysprothrombinemia. Methods: Coagulation assays, prothrombin Western Blotting, FII activation by Ecarin, fibrinogen degradation products quantification and thrombin generation assay were carried out to assess prothrombin expression and function. PCR followed by direct sequencing was carried out to characterize the mutation. In silico analysis for missense variant and molecular modeling were applied to predict the mechanism that leads to dysprothrombinemia. Results and conclusions: The homozygous patient had a markedly prolonged prothrombin time, strongly reduced FII activity (0.82%) but normal antigen levels. In the thrombin generation assay the lag time and the peak height were unmeasurable, suggesting that the Val322Glu mutation results in the inability of the mutant prothrombin to be fully activated to thrombin. In fact, prothrombin activation by ecarin was defective, with a massive accumulation of the meizothrombin intermediate. Molecular modeling and dynamic simulation studies showed that the Val322Glu mutation interferes with protein flexibility at Arg271 and Arg320. This impairs the switch of the protein from zymogen to proteinase, thus preventing the formation of thrombin. Accumulated meizothrombin, however, maintains some fibrinogen-degrading activity, as shown by the formation of FDPs, and this probably explains the patient's mild bleeding phenotype.
AB - Introduction: Prothrombin deficiency is a very rare disorder caused by mutations in the F2 gene that generate hypoprothrombinemia or dysprothrombinemia and is characterized by bleeding manifestations that can vary from clinically irrelevant to life-threatening. Aim: Here we characterize a patient with a novel missense mutation in F2, c.1090 T/A (p. Val322Glu), that causes severe dysprothrombinemia. Methods: Coagulation assays, prothrombin Western Blotting, FII activation by Ecarin, fibrinogen degradation products quantification and thrombin generation assay were carried out to assess prothrombin expression and function. PCR followed by direct sequencing was carried out to characterize the mutation. In silico analysis for missense variant and molecular modeling were applied to predict the mechanism that leads to dysprothrombinemia. Results and conclusions: The homozygous patient had a markedly prolonged prothrombin time, strongly reduced FII activity (0.82%) but normal antigen levels. In the thrombin generation assay the lag time and the peak height were unmeasurable, suggesting that the Val322Glu mutation results in the inability of the mutant prothrombin to be fully activated to thrombin. In fact, prothrombin activation by ecarin was defective, with a massive accumulation of the meizothrombin intermediate. Molecular modeling and dynamic simulation studies showed that the Val322Glu mutation interferes with protein flexibility at Arg271 and Arg320. This impairs the switch of the protein from zymogen to proteinase, thus preventing the formation of thrombin. Accumulated meizothrombin, however, maintains some fibrinogen-degrading activity, as shown by the formation of FDPs, and this probably explains the patient's mild bleeding phenotype.
KW - Dysprothrombinemia
KW - Factor II
KW - Meizothrombin
KW - Molecular modeling
KW - Prothrombin activation
UR - http://www.scopus.com/inward/record.url?scp=84927587023&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84927587023&partnerID=8YFLogxK
U2 - 10.1016/j.thromres.2014.08.028
DO - 10.1016/j.thromres.2014.08.028
M3 - Article
C2 - 25242243
AN - SCOPUS:84927587023
VL - 134
SP - 1135
EP - 1141
JO - Thrombosis Research
JF - Thrombosis Research
SN - 0049-3848
IS - 5
ER -