Mechanism underlying factor VII deficiency in Jewish populations with the Ala244Val mutation

Use of recombinant factor VII for tooth extractions in a patient with severe congenital factor VII deficiency: a case report

BACKGROUND AND OVERVIEW

Patients with factor VII deficiency have an increased risk of prolonged perioperative hemorrhage. In this article, the authors present a case of severe factor VII deficiency in a patient who required tooth extraction.

CASE DESCRIPTION

A 44-year-old woman with severe congenital factor VII deficiency sought care for a symptomatic, carious, and nonrestorable maxillary right second molar that required extraction. The authors obtained hematologic consultation, and the patient underwent the extraction under general anesthesia in the inpatient setting. Perioperative management included performing relevant laboratory studies, preoperative recombinant factor VII infusion, and postoperative intravenous aminocaproic acid administration. No hemorrhagic complications occurred throughout the perioperative course.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The degree of factor VII deficiency correlates poorly with bleeding risk. Perioperative management is variable, requiring preoperative consultation with a hematologist.

Characterization of mutations causing factor VII deficiency in 61 unrelated Israeli patients

Inherited factor (F)VII deficiency is rare in most populations but relatively common in Israel. The aim of this study was to characterize the molecular and functional defect in unrelated Israeli patients with FVII deficiency. Mutations were identified by direct sequencing of PCR-amplified genomic DNA fragments. Selected mutations were expressed in baby hamster kidney (BHK) cells and tested for binding to tissue factor (TF), activation by FXa and activation of FX. In 61 patients with FVII deficiency, the causative mutation in the FVII gene was discerned. The predominant mutation found in this and a previously reported cohort of 27 unrelated patients in Israel was Ala244Val substitution; of 121 independent mutant alleles defined in all 88 patients ascertained in Israel, 102 (84%) bore this alteration. Eleven additional mutations were identified of which one, Cys22Arg, is novel. Expression of the mutations in BHK cells revealed that four (Ala244Val, 11128delC, Leu300Pro and Cys22Arg) were cross-reacting material (CRM)- negative, and three (Ala294Val, Cys310Phe and Phe24del) were CRM-positive. As predicted by modeling, we observed no binding to TF of FVII Phe24del, diminished binding of FVII Cys310Phe and normal binding of FVII Ala294Val. The main defect of FVII Ala294Val was its inability to activate FX in the presence of TF. Coexpression of Ala294Val and Arg353Gln, a polymorphism known to affect FVII secretion, did not reveal an additive effect on FVII secretion, while coexpression of Ala244Val and Arg353Gln did yield an additive effect.

Human factor VII deficiency caused by S339C mutation located adjacent to the specificity pocket of the catalytic domain

This report documents our identification of a novel factor VII (FVII) gene mutation in a Japanese boy with FVII deficiency. The proband's FVII activity was 34% and his FVII antigen level was 40% of normal controls. DNA sequence analysis of the proband's FVII gene identified a C to G point mutation at nucleotide position 10 933 in exon 8, which results in the substitution of Cys (TGC) for Ser339 (TCC). Hinf I digestion results indicate the proband and his mother were heterozygous for the mutation. Both wild-type and mutant FVIIs were transiently expressed in COS-1 cells. FVII levels measured in the culture medium of FVII Ser339Cys mutants were markedly reduced as compared to those of cells with FVII wild-type. The amount of intracellular FVII in FVII Ser339Cys mutants was 80% of that in wild-type. In the wild-type FVII, Ser339 is juxtaposed to Asp338, which is positioned at the bottom of the substrate-binding pocket in the protease domain and located adjacent to FVII Cys340, that forms a disulphide bond with Cys368. We suspect that the creation of a novel unpaired cysteine through this mutation leads to abnormal disulphide bonding during protein folding, thereby reducing the secretion of FVII.

Isolated factor VII deficiency diagnosed after a life-threatening brain haemorrhage

A 65-year-old man was admitted to another hospital with a life-threatening brain haemorrhage, and laboratory examinations on admission revealed prolonged prothrombin time with normal activated partial thromboplastin time. To establish the cause of his abnormal coagulation, he was referred to our clinic. Neither the patient nor his family had any previous history of bleeding symptoms. His liver function was within normal limits but coagulation tests showed increased plasma activities of factors II, VIII, IX, X, with reduced activities of factors V and VII. The activity of factor VII was less than 2% but no inhibitor of factor VII was detected in the plasma. We concluded that the patient had a rare congenital isolated factor VII deficiency although he had not shown earlier bleeding problems, presumably because of compensation for the factor VII deficiency by enhanced activities of components of the extrinsic coagulation pathway, factors II, VIII, IX and X.