Variability in factor V:C assays in UK National External Quality Assessment Scheme surveys: there is a need for an international standard

Severe familial factor V:C deficiency is a rare, recessively inherited coagulation disorder but there is little information in respect of the accuracy and reliability of factor V:C assays that are required for diagnosis and treatment monitoring. We present here the results of three External Quality Assessment exercises in respect of factor V:C assays undertaken by 192--225 participating laboratories performed over a 2-year period. Consistent significant differences were observed between results obtained using different reference plasmas and different thromboplastins. The relationship between results obtained with different reference plasmas was not constant and varied between the surveys. In-house studies confirmed the observation derived from the External Quality Assessment surveys that the choice of commercial reference plasma significantly affects the results of factor V:C assays. These results clearly indicate the necessity for an international standard for factor V:C.

Association of factor V deficiency with factor V HR2

BACKGROUND AND OBJECTIVES

Factor V HR2 possesses decreased co-factor activity to activated protein C and an increased ratio of factor V1 to factor V2. Factor V HR2 is associated with a mild increase in the risk of venous thromboembolism although not all studies concur on this point.

DESIGN AND METHODS

Inconsistencies in results of the epidemiological studies may stem from a failure to identify other variables in factor V which might contribute to an increased risk of thrombosis in selected HR2 carriers. The aim of this study was to establish whether factor V deficiency increases the risk of venous thromboembolism when associated with HR2.

RESULTS

Four hundred and ninety-seven patients with venous thromboembolism and 498 controls were studied. HR2 was present in 12.5% of patients and 10.4% of controls. Factor V deficiency was associated with HR2 in 4.6% of patients and 1.0% of controls. The OR for venous thromboembolism in individual with HR2 alone was 1.2 (95% CI 0.8-1.8), while it was 4.7 (95% CI 1.8-12.5) for those with HR2 plus factor V deficiency.

INTERPRETATION AND CONCLUSIONS

Patients with HR2 and factor V deficiency developed a thrombotic event earlier (median age 35 years) than patients with HR2 alone (median age 43 years, p = 0.018). Double heterozygosity for HR2 and a factor V defect, including factor V deficiency, increased the thrombotic risk afforded by HR2.

Anti-factor V auto-antibody in the plasma and platelets of a patient with repeated gastrointestinal bleeding

Development of autoantibody against coagulation factor V (FV) is a rare clinical condition with hemorrhagic complications of varying severity. The aim of this study was to establish the pathomechanism of an acquired FV deficiency and characterize the FV inhibitor responsible for the clinical symptoms. A 78-year-old female was admitted to hospital with severe gastrointestinal bleeding. General clotting tests and determination of clotting factors were performed by standard methods. FV antigen and FV containing immune complexes were measured by ELISA. The FV molecule was investigated by Western blotting and by sequencing the f5 gene. The binding of patient's IgG to FV and activated FV (FVa) was demonstrated in an ELISA system and its effect on the procoagulant activity of FVa was tested in clotting tests and in a chromogenic prothrombinase assay. Localization of the epitope for the antibody was performed by blocking ELISA. FV activity was severely suppressed both in plasma and platelets. FV antigen levels were normal by ELISA using polyclonal anti-FV antibody or monoclonal antibody against the connecting region of FV, but depressed when HV1 monoclonal antibody against the C2 domain in the FV light-chain was used as capture antibody. The FV molecule was found intact. An IgG reacting with both FV and FVa was present in the patient's plasma and its binding to FV was inhibited by HV1 antibody. FV-containing immune complexes were detected in the patient's plasma and platelet lysate. The patient's IgG inhibited the procoagulant function of FVa. An anti-FV IgG was present in the patient's plasma and platelets. The autoantibody reacted with an epitope in the C2 domain of FV light chain and neutralized the procoagulant function of FVa.

Life-threatening bleeding and acquired factor V deficiency associated with primary systemic amyloidosis

Acquired factor X deficiency has been described in patients with amyloidosis but acquired factor V deficiency is quite rare. We report here a case of life-threatening bleeding and acquired factor V deficiency associated with primary amyloidosis. A 50-year-old man who had no previous hemorrhagic diathesis was referred to our hospital because of recurrent epistaxis, gingival bleeding and hemospermia. The laboratory examination revealed that both the prothrombin time (PT) and the activated partial thromboplastin time (aPTT) were significantly prolonged, and factor V activities were markedly decreased to 14-39% of the normal value. Other coagulation factors such as fibrinogen, prothrombin, factor VII, factor VIII, factor IX and factor X were subnormal and normal. Transaminases were slightly elevated but serological tests of hepatitis B and hepatitis C were negative. Mild hepatosplenomegaly was noted without sign of liver cirrhosis. The PT and aPTT obtained 8 years ago when he received a cholecystectomy due to cholecystitis were both normal. Specific assays for the detection of factor V inhibitor were repeatedly performed but no factor V inhibitor was found. Furthermore, a significant recovery of the infused factor V was noted shortly after an intravenous administration of 5-10 U fresh frozen plasma, but it did not last more than 6 h. Melena, bleedings into the left shoulder and buttock, and finally mortal retroperitoneal hemorrhage developed despite repeated infusions of large amounts of fresh frozen plasma. Acquired factor V deficiency associated with primary amyloidosis was suspected but histological diagnosis was not obtained because of the severe bleeding tendency. Autopsy revealed hepatosplenomegaly and massive deposits of AL amyloid in the liver, spleen, heart and other parenchymal organs. Perivascular amyloid deposition and factor V deficiency are both thought to be the cause of the severe hemorrhagic tendency seen in this patient.

Hereditary combined coagulation factor V and factor VIII deficiency: report of two Indian families from Varanasi

Hereditary deficiencies of blood coagulation factors usually involve a single protein defect. Herewith we are describing clinical features and laboratory approach for the diagnosis of combined coagulation factor V/VIII deficiency which we encountered in 3 patients from 2 unrelated Hindu families of Varanasi.

[Severe congenital factor V deficiency: case report]

INTRODUCTION

Congential deficiency of factor V is a rare condition, transmitted in autosomal recessive way. Heterozygote patients generally have no symptoms, homozygotes present with spontaneous and postoperative bleedings. About one-half of patients are diagnosed in adulthood.

METHODS

The presented case is a double heterozygote, which was confirmed using moleculare biological methods. The authors found many carriers in his family.

CONCLUSIONS

This rare and sometimes severe disorder needs regular haematological controls. Carriers must have more attention during surgical procedures and labour, and the family doctor should be informed about there condition.

Late presentation of congenital factor V deficiency--a case report

Congenital factor deficiency is a rare coagulation disorder, which is inherited in an autosomal recessive manner. The severity of bleeding symptoms in general is only partially related to the degree of factor V deficiency in plasma. In this report, a boy presenting with hemarthrosis in his late adolescence due to congenital factor V deficiency is reported.

[Intracranial hemorrhages in infants: child abuse or a congenital coagulation disorder?]

In children with head injuries the severity of the neurological symptoms should concord with the patient's history and signs of neurotrauma on examination. Discrepancies between the (hetero)anamnesis and physical examination on the one hand and neurological findings on the other may indicate child abuse. The presence of both old and new intracranial haemorrhages in the absence of proportional trauma is generally considered as evidence for child abuse. However, these symptoms may also be the first manifestation of a congenital coagulation disorder. Three children, two girls aged 8 and 5 months and a boy aged 6 months were presented with alarming neurological symptoms due to intracranial haemorrhages without external signs of head trauma. The first girl had 'shaken baby' syndrome while the other 2 had congenital coagulation disorders (haemophilia B and factor V deficiency, respectively). All three recovered, the last two with remaining one-sided neurological deficits. Child abuse and congenital coagulation disorders may present with similar neurological symptoms and radiological findings. In these patients coagulation tests are mandatory and--if abnormal--enable early substitution of deficits and prevent inappropriate suspicion or accusation of caretakers.

A novel two base pair deletion in the factor V gene associated with severe factor V deficiency

We studied a family in which the proband, a 13-year-old boy, had unmeasurable plasma levels of coagulation factor V antigen and activity. Clinical symptoms were severe, with several episodes of haemorrhages in the mucosal tracts (gastrointestinal, nose and urinary) and recurrent haemarthroses that caused permanent arthropathy. Sequence analysis of the factor V gene demonstrated the presence of a novel 2 base pair (bp) homozygous deletion in exon 13 at positions 2833-2834. This mutation, present in the heterozygous state in the asymptomatic mother and absent in the healthy brother, introduced a frameshift and a premature stop at codon 900. This would predict the synthesis of a truncated factor V molecule, lacking part of the B domain and the complete light chain. Because of the existence of a surveillance mechanism that selectively recognizes and degrades mRNA molecules carrying premature termination codons, we analysed the relative abundance of mutant vs. wild-type mRNA molecules in the platelets of the heterozygous proband's mother. The mutant mRNA was significantly reduced in amount (mutant/wild-type ratio 0.35). This is the first reported mutation in the factor V gene causing severe factor V deficiency, the effect of which was quantitatively analysed at mRNA level.

Spectrum of hereditary coagulation factor deficiencies in eastern province, Saudi Arabia

In a 7-year retrospective analysis (1991-97) of the records of the Department of Haematology, Regional Laboratory and Blood Bank (Dammam), 54 patients from all parts of Saudi Arabia's Eastern Province were diagnosed with hereditary coagulation factor deficiencies. The largest group of patients, 42 haemophiliacs, included 4 non-Saudi patients. There were 39 haemophilia A or factor VIII deficiency patients, 2 haemophilia B or factor IX deficiency patients and 1 combined factor VIII and V deficiency patient. There were 5 Saudi patients with probable factor XIII deficiency, and 7 patients, all but one who were Saudi, had von Willebrand disease. The distribution of haemophilia patients in Eastern Province showed some differences compared with those reported from Riyadh and from Western countries. Among Saudis in Eastern Province, the number with suspected factor XIII deficiency, although low, was higher than that reported for other regions. The number of patients with haemophilia B and von Willebrand disease was lower than expected, when compared with the number of haemophilia A cases.

Development of a simple multiplex polymerase chain reaction for the simultaneous detection of factor V Leiden and prothrombin 20210A mutations

BACKGROUND

The demand for thrombophilia testing at the molecular level is increasing, and consequently, the work load of the routine molecular laboratory is also increasing. Efforts to lighten the work load, economize on time, and strive for reduced costs while still maintaining quality assurance are thus necessary.

METHODS AND RESULTS

A multiplex polymerase chain reaction (PCR) for the detection of factor V Leiden and prothrombin 20210A mutations was designed that enables the use of the same inexpensive restriction enzyme, controls for the digestion, and produces easily interpretable results.

CONCLUSION

The use of this new multiplex PCR and digestion analysis enabled us to simultaneously perform a routine screen for factor V Leiden and prothrombin 20210A mutations.

[The concomitant presence of prohemorrhagic and thrombophilic changes in coagulation factor V: a severe defect of coagulant activity and homozygote resistance to activated protein C]

We describe the peculiar and concomitant presence of a severe coagulation defect predisposing to bleeding and a mutation associated with inherited thrombophilia. A 6-year-old boy had a severe deficiency in factor V procoagulant activity and antigen and yet remained asymptomatic. This paradox might be explained by the hypothesis of the simultaneous presence of a thrombophilic disorder that might have restored hemostatic balance. The boy was a homozygous carrier of the Arg506Gln mutation of coagulation factor V, that renders this factor resistant to inactivation by its naturally occurring inhibitor, activated protein C. The family members, none of whom had bleeding or thrombotic symptoms, were heterozygotes for either the bleeding or the thrombophilic defect. Despite the severity of the bleeding defect, the absence of bleeding symptoms in the boy can be explained by the hypothesis that any residual amount of factor V present in his plasma is resistant to inactivation by activated protein C.

Intracranial haemorrhage due to factor V deficiency

Factor V deficiency is a rare coagulation disorder which is inherited autosomal recessively. Factor V deficiency should be considered in infants with bleeding disorders and prolonged prothrombin and activated partial thromboplastin times if bleeding continues in spite of vitamin K injection. In this article, the case of an infant with an intracranial haemorrhage due to congenital factor V deficiency is reported.

[Three patients with a kidney infarct]

Two patients, one 76-year-old-man and one 79-year-old-woman with cardiovascular disease and one 36-year-old-man with Factor-V-Leiden deficiency (activated protein C-resistance) had abdominal pain and elevation of LDH levels. With abdominal CT scan kidney infarction was diagnosed. In two cases a selective kidney arteriography was performed to confirm the diagnosis. Treatment consisted of (re)starting anticoagulant therapy. In unexplained abdominal pain with insufficiently specific results of physical examination combined with a rapid rise of the LDH and sometimes of the serum creatinine, a kidney infarction should be considered in the differential diagnosis.

A protein C pathway (PCP) screening test for the detection of APC resistance and protein C or S deficiencies

A new automated method for screening defects in the Protein C Pathway (PCP) was evaluated. The "PCP test" is based on a phospholipid-rich Russells viper venom reagent, insensitive to heparin and lupus anticoagulants. To minimize interference from other clotting variables, ratios of the clotting time with and without the addition of a protein C activator were usually determined. Plasma samples from healthy volunteers, patients untreated or on oral anticoagulants, patients with factor V Leiden with and without treatment, and patients with protein C and/or S deficiencies were tested. Mixing patient plasmas 1:1 with individual plasmas deficient in factor V, protein C or S was evaluated for identifying the nature of defects by shortening the screening test. The PCP test was found to be sensitive to APC resistance due to factor V Leiden and by mixing with factor V deficient plasma was also useful despite the effects of oral anticoagulants. Results in the group of patients with previous low protein C or S levels suggest that the method has a better sensitivity to protein C than to protein S deficiency. The automated test was simple to use and gave a between-run coefficient of variation below 3% on normal plasmas.

Hemorrhagic and thrombotic disorders due to factor V deficiencies and abnormalities: an updated classification

The recent description of a factor V abnormality (factor V Leiden) associated with an increased incidence of thrombosis has considerably increased interest in this clotting factor. The discovery of this new clinical entity indicated the need for an updated classification of factor V defects. These should be divided into hemorrhagic and thrombotic disorders. A proper classification of hemorrhagic disorders should include: 1) homozygous and heterozygous 'true' factor V deficiency; and 2) combined factor V and factor VIII deficiencies. The latter should be subdivided in Type I (association type) and Type II (common defect). A suitable classification of the thrombotic factor V defects should include: 1) homozygous and heterozygous factor V Leiden; and 2) combined heterozygous factor V Leiden and heterozygous 'true' factor V deficiency. The presence of thrombosis in these latter patients, often as severe as those seen in homozygous patients with activated protein C (APC) resistance, allows important considerations on the functions of factor V. It would seem that half the normal level of factor V activity and antigen is unable to protect against thrombosis in patients with heterozygous APC resistance. An accurate evaluation of factor V activity and antigen is indicated in all patients with suspected factor V defects. The first suspicion may be obtained by the presence of a mild prolongation of prothrombin time and of partial thromboplastin time. The suspicion should then be immediately confirmed by specific factor V activity and antigen assays. This approach is of great importance even for the presumptive diagnosis of pseudohomozygosis for APC resistance. In fact, in these cases, factor V activity is about 50% of normal, whereas factor V antigen is 100% of normal. In heterozygous 'true' factor V deficiency both activity and antigen are about 50% of normal.

A case of factor V deficiency presenting as menorrhagia

Factor V deficiency is a rare hereditary disorder. We report a patient with factor V deficiency who presented with menorrhagia and pelvic haematoma. The Haematology Department at the Royal Brisbane Hospital performed the definitive factor assays leading to the diagnosis. The challenges of her management were obtaining adequate supplies of factor V and her socioeconomic circumstances. The main future challenge will be the supervision of her pregnancies.