Combined factor V and factor VIII deficiency among non-Ashkenazi Jews

Clinical, Laboratory, Molecular, and Reproductive Aspects of Combined Deficiency of Factors V and VIII

Congenital combined deficiency of factor V (FV) and factor VIII (FVIII; F5F8D, OMIM 227300) is a rare hereditary coagulopathy and accounts for approximately 3% of cases of rare coagulation disorders. The prevalence of this disease in the general population is estimated to be 1:1,000,000 and is significantly higher in regions where consanguineous marriages are permitted, such as the Mideast and South Asia. The disease has an autosomal recessive mode of inheritance and therefore occurs with an equal incidence among males and females. Heterozygous mutation carriers usually do not have clinical manifestations. The molecular basis of this disease differs from that of stand-alone congenital deficiencies of FVIII and FV. F5F8D is caused by mutations in either LMAN1 or MCFD2, which encode components of a cargo receptor complex for endoplasmic reticulum to Golgi transport of FV and FVIII, leading to defects in an intracellular transport pathway shared by these two coagulation factors. Congenital combined deficiency of FV and FVIII is characterized by decreased activities of both FV and FVIII in plasma, usually to 5 to 30% of normal. Clinical manifestations in most cases are represented by mild or moderate hemorrhagic syndrome. The simultaneous decreases of two coagulation factors present complications in the diagnosis and management of the disease. In female patients, the disease requires a special approach for family planning, pregnancy management, and parturition. This review summarizes recent progress in clinical, laboratory, and molecular understanding of this disorder.

Management of rare inherited bleeding disorders: Proposals of the French Reference Centre on Haemophilia and Rare Coagulation Disorders

INTRODUCTION

The rare coagulation disorders may present significant difficulties in diagnosis and management. In addition, considerable inter-individual variation in bleeding phenotype is observed amongst affected individuals, making the bleeding risk difficult to assess in affected individuals. The last international recommendations on rare inherited bleeding disorders (RIBDs) were published by the United Kingdom Haemophilia Centre Doctors' Organisation in 2014. Since then, new drugs have been marketed, news studies on surgery management in patients with RIBD have been published, and new orphan diseases have been described.

AIM

Therefore, the two main objectives of this review, based on the recent recommendations published by the French Reference Centre on Haemophilia and Rare Bleeding Disorders, are: (i) to briefly describe RIBD (clinical presentation and diagnostic work-up) to help physicians in patient screening for the early detection of such disorders; and (ii) to focus on the current management of acute haemorrhages and long term prophylaxis, surgical interventions, and pregnancy/delivery in patients with RIBD.

Molecular basis of rare congenital bleeding disorders

Rare bleeding disorders (RBDs), including factor (F) I, FII, FV, FVII, combined FV and FVIII (CF5F8), FXI, FXIII and vitamin-K dependent coagulation factors (VKCF) deficiencies, are a heterogeneous group of hemorrhagic disorder with a variable bleeding tendency. RBDs are due to mutation in underlying coagulation factors genes, except for CF5F8 and VKCF deficiencies. FVII deficiency is the most common RBD with >330 variants in the F7 gene, while only 63 variants have been identified in the F2 gene. Most detected variants in the affected genes are missense (>50% of all RBDs), while large deletions are the rarest, having been reported in FVII, FX, FXI and FXIII deficiencies. Most were located in the catalytic and activated domains of FXI, FX, FXIII and prothrombin deficiencies. Understanding the proper molecular basis of RBDs not only can help achieve a timely and cost-effective diagnosis, but also can help to phenotype properties of the disorders.

Gastrointestinal Bleeding in Congenital Bleeding Disorders

Gastrointestinal bleeding (GIB) is serious, intractable, and potentially life-threatening condition. There is considerable heterogeneity in GIB phenotypes among congenital bleeding disorders (CBDs), making GIB difficult to manage. Although GIB is rarely encountered in CBDs, its severity in some patients makes the need for a comprehensive and precise assessment of underlying factors and management approaches imperative. Initial evaluation of GIB begins with assessment of hematological status; GIB should be ruled out in patients with chronic anemia, and in presentations that include hematemesis, hematochezia, or melena. High-risk patients with recurrent GIB require urgent interventions such as replacement therapy for treatment of coagulation factor deficiency (CFD). However, the best management strategy for CFD-related bleeding remains controversial. While several investigations have identified CBDs as potential risk factors for GIB, research has focused on assessing the risks for individual factor deficiencies and other CBDs. This review highlights recent findings on the prevalence, management strategies, and alternative therapies of GIB related to CFDs, and platelet disorders.

Low factor V level ameliorates bleeding diathesis in patients with combined deficiency of factor V and factor VIII

Combined factor V and factor VIII deficiency is a rare disorder associated with relatively mild bleeding diathesis. Shao and colleagues elucidate the double role of factor V as both a pro- and anticoagulant protein, demonstrating that decreased factor V may ameliorate factor VIII deficiency through decreasing the level of tissue factor pathway inhibitor.

The use of prophylaxis in the treatment of rare bleeding disorders

Rare bleeding disorders (RBDs) are a heterogeneous group of coagulation factor deficiencies that include fibrinogen, prothrombin, α₂-antiplasmin, plasminogen activator inhibitor-1, and factors II, V, V/VIII, VII, X, XI and XIII. The incidence varies based upon the disorder and typically ranges from 1 in 500,000 to 1 per million population. Symptoms vary with the disorder and residual level of the clotting factor, and can range from relatively minor such as epistaxis, to life threatening, such as intracranial hemorrhage. Rapid treatment of bleeding episodes in individuals with severe bleeding phenotypes is essential to preserve life or limb and to prevent long-term sequelae; therapeutic options depend on the deficiency and range from plasma-derived (eg, fresh frozen plasma, prothrombin complex concentrates, factor X concentrate) to highly purified and recombinant single factor concentrates. The rarity of these disorders limits the feasibility of conventional prospective clinical trials; instead, clinicians rely upon registries, published case reports/series and experience to guide treatment. In some disorders, long-term prophylactic therapy is administered in response to the bleeding phenotype in an individual patient or based on the known natural history and severity of the deficiency. Intermittent prophylaxis, surrounding surgery, pregnancy, labor, and menstruation may be required to prevent or control excessive bleeding. This review summarizes therapeutic options, guidelines, recommendations and observations from the published literature for long-term, surgical, gynecological, and obstetric prophylaxis in deficiencies of fibrinogen; prothrombin; factors II, V, V/VIII, VII, X, XI and XIII; combined vitamin-K dependent factors; α2-antiplasmin; and plasminogen activator inhibitor 1. Platelet disorders including Glanzmann's thrombasthenia and Bernard-Soulier syndrome are also addressed.

Analysis of MCFD2- and LMAN1-deficient mice demonstrates distinct functions in vivo

The LMAN1-MCFD2 complex serves as a cargo receptor for efficient transport of factor V (FV) and FVIII from the endoplasmic reticulum (ER) to the Golgi. Genetic deficiency of LMAN1 or MCFD2 in humans results in the moderate bleeding disorder combined FV and FVIII deficiency, with a similar phenotype previously observed in LMAN1-deficient mice. We now report that MCFD2-deficient mice generated by gene targeting also demonstrate reduced plasma FV and FVIII, with levels lower than those in LMAN1-deficient mice, similar to previous observations in LMAN1- and MCDF2-deficient humans. Surprisingly, FV and FVIII levels in doubly deficient mice match the higher levels observed in LMAN1-deficient mice. In contrast to the strain-specific partial lethality previously observed in LMAN1-null mice, MCFD2-null mice demonstrate normal survival in different genetic backgrounds, although doubly deficient mice exhibit partial embryonic lethality comparable to LMAN1-deficient mice. These results suggest that an alternative pathway is responsible for FV/FVIII secretion in doubly deficient mice and distinct cargo-specific functions for LMAN1 and MCFD2 within the ER-to-Golgi secretory pathway. We also observed decreased plasma levels of α1-antitrypsin (AAT) in male mice for all 3 groups of deficient mice. Comparable accumulation of AAT was observed in hepatocyte ER of singly and doubly deficient mice, demonstrating a role for LMAN1 and MCFD2 in efficient ER exit of AAT.

Genotype and phenotype report on patients with combined deficiency of factor V and factor VIII in Iran

Combined factor V (FV) and factor VIII (FVIII) deficiency is a rare autosomal recessive bleeding disorder characterized by mild-to-moderate bleeding. Epistaxis, postsurgical bleeding and menorrhagia are the most common symptoms. The aim of this study is to report the phenotype-genotype characterization carried out in patients affected with combined FV and FVIII deficiency from Iran. A cross-sectional study was conducted in Shiraz Hemophilia Center, southern Iran. Twelve cases, seven men and five women coming from eight families were included in our study after taking consent form. Coagulation activity for all patients was measured. All exons and intron-exon junctions of lectin mannose binding protein 1 (LMAN1) gene and multiple coagulation factor deficiency 2 genes were amplified by PCR, and subsequently sequenced by the Sanger method. Patients[Combining Acute Accent] age ranged from 6 to 59 years mean ± SD: 23.8 ± 15.4 years and median: 22 years. No patient presented with severe bleeding symptom. Only one patient had severe FV and FVIII deficiency (both factor levels <1%). Four different type of mutations (duplication, insertion, splice site and nonsense), occurring in different locuses, were identified on LMAN1 gene in 12 Iranian patients. There was a significant correlation between FV and FVIII levels, which is indicative of association with loss of function of LMAN1 gene, and reduced plasma levels of both factors. Our study showed that all of our characterized patients with combined FV and FVIII deficiency present different homozygous mutations on LMAN1 gene introducing a premature stop codon. Larger studies are needed to calculate the correlation between factor levels, genetic and bleeding symptoms.

Combined deficiency of coagulation factors V and VIII: an update

Combined deficiency of factor V (FV) and FVIII (F5F8D) is an autosomal recessive bleeding disorder characterized by simultaneous decreases of both coagulation factors. This review summarizes recent reports on the clinical presentations, treatments, and molecular mechanism of F5F8D. Genetic studies identified LMAN1 and MCFD2 as causative genes for this disorder, revealing a previously unknown intracellular transport pathway shared by the two important blood coagulation factors. LMAN1 and MCFD2 form a Ca2+-dependent cargo receptor complex that functions in the transport of FV/FVIII from the endoplasmic reticulum (ER) to the Golgi. Disrupting the LMAN1-MCFD2 receptor, complex formation is the primary molecular defect of missense mutations leading to F5F8D. The EF-hand domains of MCFD2 are necessary and sufficient for the interactions with both LMAN1 and FV/FVIII. Similarly, the carbohydrate recognition domain of LMAN1 contains distinct and separable binding sites for both MCFD2 and FV/FVIII. Therefore, FV and FVIII likely carry duel sorting signals that are separately recognized by LMAN1 and MCFD2 and necessary for the efficient ER-to-Golgi transport. FV and FVIII likely bind LMAN1 through the high-mannose N-linked glycans under the higher Ca2+ conditions in the ER and dissociate in the lower Ca2+ environment of the ER-Golgi intermediate compartment.

Successful percutaneous coronary intervention in a patient with combined deficiency of FV and FVIII due to novel compound heterozygous mutations in LMAN1

Percutaneous coronary intervention (PCI) in patients with congenital coagulation factor deficiencies presents a unique challenge. They are not only at increased risk of perioperative bleeding but can also suffer thrombosis of the stent as preventive anticoagulation and antiplatelet therapy is difficult. Several cases of successful PCI have been described in patients with haemophilia A and B, but there are no reports in patients with combined coagulation factor deficiencies. We used PCI to treat the coronary artery disease in a patient with the combined deficiency of factor V and factor VIII (F5F8D) and analysed the molecular basis of the disorder for this patient. A 68-year-old patient was admitted for urgent PCI with bare metal stent placement after the diagnosis of the F5F8D. Peripheral blood DNA was extracted for the sequence analysis of LMAN1 and MCFD2 genes. Mutations in LMAN1 was confirmed by molecular cloning of the PCR product and resequencing of the resulting clones. The patient underwent successful PCI with good long-term outcome. Our patient tolerated anticoagulation therapy well, with unfractionated heparin, and double antiplatelet therapy while he was initially supported with fresh frozen plasma and recombinant FVIII. Molecular analysis revealed that the patient carries unusual compound heterozygous frameshift mutations on the same microsatellite repeat region in exon 8 of LMAN1, one of which is a novel mutation (c.912delA). Our results suggest that patients with F5F8D can safely undergo PCI for coronary artery disease, with the treatment individualized to the specific patient.

Developmental haemostasis for factor V and factor VIII levels in neonates: a case report of spontaneous cephalhaematoma

Combined factor V and VIII deficiency is a rare bleeding disorder. Diagnosis of congenital coagulation factor deficiency in a neonate is challenging due to "immaturity" of the hemostatic system. A 2-day-old baby girl presented with spontaneous cephalhematoma. She was found to have persistent abnormal coagulation tests and finally diagnosed as combined factor V and VIII deficiency. Interestingly, factor V and factor VIII in developmental hemostasis are quite similar with adult levels in newborn, and hence early diagnosis is possible. An investigation to detect underlying hemostatic defects is recommended in newborns with spontaneous cephalhematoma.

Inherited hematological disorders due to defects in coat protein (COP)II complex

Many diseases attributed to trafficking defects are primary disorders of protein folding and assembly. However, an increasing number of disease states are directly attributable to defects in trafficking machinery. In this context, the cytoplasmic coat protein (COP)II complex plays a pivotal role: it mediates the anterograde transport of correctly folded secretory cargo from the endoplasmic reticulum towards the Golgi apparatus. This review attempts to describe the involvement of COPII complex alteration in the pathogenesis of human genetic disorders; particularly, we will focus on two disorders, the Congenital Dyserythropoietic Anemia type II and the Combined Deficiency of Factor V and VIII.

The COPII pathway and hematologic disease

Multiple diseases, hematologic and nonhematologic, result from defects in the early secretory pathway. Congenital dyserythropoietic anemia type II (CDAII) and combined deficiency of coagulation factors V and VIII (F5F8D) are the 2 known hematologic diseases that result from defects in the endoplasmic reticulum (ER)-to-Golgi transport system. CDAII is caused by mutations in the SEC23B gene, which encodes a core component of the coat protein complex II (COPII). F5F8D results from mutations in either LMAN1 (lectin mannose-binding protein 1) or MCFD2 (multiple coagulation factor deficiency protein 2), which encode the ER cargo receptor complex LMAN1-MCFD2. These diseases and their molecular pathogenesis are the focus of this review.

Analysis of newly detected mutations in the MCFD2 gene giving rise to combined deficiency of coagulation factors V and VIII

Combined deficiency of coagulation factor V (FV) and factor VIII (FVIII) (F5F8D) is a rare autosomal recessive disorder characterized by mild-to-moderate bleeding and reduction in FV and FVIII levels in plasma. F5F8D is caused by mutations in one of two different genes, LMAN1 and MCFD2, which encode proteins that form a complex involved in the transport of FV and FVIII from the endoplasmic reticulum to the Golgi apparatus. Here, we report the identification of a novel mutation Asp89Asn in the MCFD2 gene in a Tunisian patient. In the encoded protein, this mutation causes substitution of a negatively charged aspartate, involved in several structurally important interactions, to an uncharged asparagine. To elucidate the structural effect of this mutation, we performed circular dichroism (CD) analysis of secondary structure and stability. In addition, CD analysis was performed on two missense mutations found in previously reported F5F8D patients. Our results show that all analysed mutant variants give rise to destabilized proteins and highlight the importance of a structurally intact and functional MCFD2 for the efficient secretion of coagulation factors V and VIII.

Two New Mutations at ERGIC-53 Gene in a Turkish Family

Combined factor V and factor VIII deficiency (F5F8D) is a rare autosomal recessive coagulation disorder associated with plasma levels of coagulation factors V and VIII approximately 5% to 30% normal. Combined factor V and factor VIII deficiency is caused by mutations in ERGIC-53 (LMAN1) gene. ERGIC-53 and multiple coagulation factor deficiency 2 (MCFD2) form a protein complex that functions as a cargo receptor transport FV and FVIII from the endoplasmic reticulum to the Golgi. The aim of this study was to determine the mutations of ERGIC-53 (endoplasmic reticulum [ER] to the ER-Golgi intermediate compartment) gene and combined F5F8D in a family. In this study, we analyzed a patient in a Turkish family with combined F5F8D. We found a nonsense mutation of C to T at nucleotide 202 in exon 9, resulting in a transition of arginine to stop codon, and in 1 child, we found a timine deletion in exon 4 in ERGIC-53 gene.

A review of long-term prophylaxis in the rare inherited coagulation factor deficiencies

The rare inherited coagulation factor deficiencies (deficiencies of factors I, II, V, VII, XI, XIII, combined FV + FVII deficiency, combined deficiency of the vitamin K dependent factors and von Willebrand disease type 3) have an aggregate prevalence of approximately 1:100,000. They may cause recurrent life or function threatening haemorrhage. In this article we review the available literature on long-term prophylaxis and, where possible, make recommendations on this important area.

A novel missense mutation causing abnormal LMAN1 in a Japanese patient with combined deficiency of factor V and factor VIII

Combined deficiency of coagulation factor V (FV) and factor VIII (FVIII) (F5F8D) is an inherited bleeding disorder characterized by a reduction in plasma concentrations of FV and FVIII. F5F8D is genetically linked to mutations in either LMAN1 or MCFD2. Here, we investigated the molecular basis of F5F8D in a Japanese patient, and identified a novel missense mutation (p.Trp67Ser, c.200G>C) in the LMAN1, but no mutation in the MCFD2. The amount of LMAN1 in Epstein-Barr virus-immortalized lymphoblasts from the patient was found to be almost the same as that in cells from a normal individual. Interestingly, an anti-MCFD2 antibody did not co-immunoprecipitate the mutant LMAN1 with MCFD2 in lymphoblasts from the patient, suggesting the affinity of MCFD2 for the mutant LMAN1 is weak or abolished by the binding of the anti-MCFD2 antibody. In addition, a Myc/6xHis-tagged recombinant form of wild-type LMAN1 could bind to D-mannose, but that of the mutant could not. The p.Trp67Ser mutation was located in the carbohydrate recognition domain (CRD), which is thought to participate in the selective binding of LMAN1 to the D-mannose of glycoproteins as well as the EF-motif of MCFD2. Taken together, it was suggested that the p.Trp67Ser mutation might affect the molecular chaperone function of LMAN1, impairing affinity for D-mannose as well as for MCFD2, which may be responsible for F5F8D in the patient. This is the first report of F5F8D caused by a qualitative defect of LMAN1 due to a missense mutation in LMAN1. Am. J. Hematol. 2009. (c) 2009 Wiley-Liss, Inc.

Familial multiple coagulation factor deficiencies - chance associations and distinct clinical disorders

The familial multiple coagulation factor deficiencies (FMCFDs) are a group of rare haemostatic disorders of genetic origin in which there is reduced plasma activity of more than one coagulation factor. FMCFDs may arise from co-incidental inheritance of separate coagulation factor deficiencies or from a single genetic or cytogenetic defect. All the FMCFDs present significant challenges in diagnosis and management yet there is little systematic evidence with which to guide clinical practice. This review summarizes the historical literature that describes the FMCFDs and introduces a refined classification of these disorders. The clinical and laboratory characteristics of the most common FMCFDs are considered in detail.

[Appropriate laboratory investigation in women with menorrhagia]

Inherited bleeding disorders are potentially causes of menorrhagia and must be investigated if no specific cause is identified. The reported prevalence of inherited bleeding disorders is high in women with menorrhagia compared to the general population. The most frequent disorders reported are von Willebrand's disease and Factor XI deficiency. Menorrhagia is, also, a frequent finding in women with congenital bleeding disorders. Morever, menorrhagia represents the major cause of iron-deficiency anemia among women of reproductive age. Primary evaluation for an underlying disorder of hemostasis in a woman wih menorrhagia is a focused history for familiy and personal history of bleeding symptoms and a complete blood cell count. This will rule out thrombocytopenic bleeding and also assesses for the degree, if any, of anemia. Those women with a positive screen and normal platelet count should be evaluated with laboratory investigation including prothrombin time, activated partial thromboplastin time, factor VIII, VWF ristocetin cofactor and antigen. If initial hemostasis testing above is normal, then further hemostasis testing can be considered, especially in terms of platelet aggregation, in a multidisciplinary clinic.

Recent developments in the understanding of the combined deficiency of FV and FVIII

Combined deficiency of factor V (FV) and factor VIII (FVIII) (F5F8D) is a genetic disorder characterized by mild-to-moderate bleeding and coordinate reduction in plasma FV and FVIII levels, as well as platelet FV level. Recent studies identified mutations in two genes (LMAN1 and MCFD2) as the cause of F5F8D. Though clinically indistinguishable, MCFD2 mutations generally exhibit lower levels of FV and FVIII than LMAN1 mutations. LMAN1 is a mannose-specific lectin that cycles between the endoplasmic reticulum (ER) and the ER-Golgi intermediate compartment. MCFD2 is an EF-hand domain protein that forms a calcium-dependent heteromeric complex with LMAN1 in cells. Missense mutations in the EF-hand domains of MCFD2 abolish the interaction with LMAN1. The LMAN1-MCFD2 complex may serve as a cargo receptor for the ER-to-Golgi transport of FV and FVIII, and perhaps a number of other glycoproteins. The B domain of FVIII may be important in mediating its interaction with the LMAN1-MCFD2 complex.

Genotype-phenotype correlation in combined deficiency of factor V and factor VIII

Combined deficiency of factor V and factor VIII (F5F8D) is caused by mutations in one of 2 genes, either LMAN1 or MCFD2. Here we report the identification of mutations for 11 additional F5F8D families, including 4 novel mutations, 2 in MCFD2 and 2 in LMAN1. We show that a novel MCFD2 missense mutation identified here (D81Y) and 2 previously reported mutations (D89A and D122V) abolish MCFD2 binding to LMAN1. Measurement of platelet factor V (FV) levels in 7 F5F8D patients (4 with LMAN1 and 3 with MCFD2 mutations) demonstrated similar reductions to those observed for plasma FV. Combining the current data together with all previous published reports, we performed a genotype-phenotype analysis comparing patients with MCFD2 mutations with those with LMAN1 mutations. A previously unappreciated difference is observed between these 2 classes of patients in the distribution of plasma levels for FV and factor VIII (FVIII). Although there is considerable overlap, the mean levels of plasma FV and FVIII in patients with MCFD2 mutations are significantly lower than the corresponding levels in patients with LMAN1 mutations. No differences in distribution of factor levels are observed by sex. These data suggest that MCFD2 may play a primary role in the export of FV and FVIII from the ER, with the impact of LMAN1 mediated indirectly through its interaction with MCFD2.

Mutations in the MCFD2 gene are predominant among patients with hereditary combined FV and FVIII deficiency (F5F8D) in India

Combined FV and FVIII deficiency (F5F8D) is a rare (1:1.000.000) autosomal recessive disorder caused by a defect in the LMAN1 or MCFD2 genes, encoding for a FV and FVIII cargo receptor complex. We report the phenotype and genotype analyses in nine unrelated Indian patients with low FV and FVIII coagulant activity [FV:C, range: 5.6-22.4% and FVIII:C, range: 8.3-27.1%]. Four homozygous mutations, including two frame shift, one missense and one splice site, were identified in all the nine patients. Three of them, a 72-bp deletion in LMAN1 (c.813_822 + 62del72, p.K272fs), a 35-bp deletion in MCFD2 (c.210_244del35) and a missence mutation in MCFD2 (p.D122V), identified in four patients, were novel mutations. A previously reported c.149 + 5G > A transition in MCFD2 was identified in the remaining five patients. Haplotype analysis of MCFD2 gene in patients with p.E71fs and c.149 + 5G > A defects suggested an independent origin of both these mutations. The identification of two common mutations (p.E71fs, c.149 + 5G > A) in MCFD2 gene in seven of nine patients, particularly the c.149 + 5G > A (55,6% of patients), suggests that this gene could be the first to be analysed during the genetic diagnosis of F5F8D in this population. This is the first report describing the molecular analysis of a consistent number of F5F8D patients of South Indian origin, a population with a high frequency of such recessive bleeding disorders.

Combined deficiency of factor V and factor VIII is due to mutations in either LMAN1 or MCFD2

Mutations in LMAN1 (ERGIC-53) or MCFD2 cause combined deficiency of factor V and factor VIII (F5F8D). LMAN1 and MCFD2 form a protein complex that functions as a cargo receptor ferrying FV and FVIII from the endoplasmic reticulum to the Golgi. In this study, we analyzed 10 previously reported and 10 new F5F8D families. Mutations in the LMAN1 or MCFD2 genes accounted for 15 of these families, including 3 alleles resulting in no LMAN1 mRNA accumulation. Combined with our previous reports, we have identified LMAN1 or MCFD2 mutations as the causes of F5F8D in 71 of 76 families. Among the 5 families in which no mutations were identified, 3 were due to misdiagnosis, with the remaining 2 likely carrying LMAN1 or MCFD2 mutations that were missed by direct sequencing. Our results suggest that mutations in LMAN1 and MCFD2 may account for all cases of F5F8D. Immunoprecipitation and Western blot analysis detected a low level of LMAN1-MCFD2 complex in lymphoblasts derived from patients with missense mutations in LMAN1 (C475R) or MCFD2 (I136T), suggesting that complete loss of the complex may not be required for clinically significant reduction in FV and FVIII.

Mutations in the MCFD2 gene and a novel mutation in the LMAN1 gene in Indian families with combined deficiency of factor V and VIII

Combined deficiency of factors V (FV) and factor VIII (FVIII) (F5F8D) is an autosomal recessive bleeding disorder caused by simultaneous moderate-to-mild decrease of both clotting proteins. Mutations in two components of the ER-Golgi intermediate compartment (ERGIC-53), i.e., lectin mannose binding protein (LMAN1) and multiple coagulation factor deficiency 2 (MCFD2), have been found to be responsible for this dual deficiency in most of the cases reported in literature. Three Indian families with F5F8D were analyzed for the presence of mutations in their LMAN1 and MCFD2 genes. One of the three families showed the presence of a G to A substitution in exon 2 of the MCFD2 gene, whereas another family showed a nonsense mutation, i.e., G to T substitution, in exon 2 of the LMAN1 gene, the latter being a novel mutation not previously reported. The third family did not show mutations in either of the two genes, suggesting that a significant subset of F5F8D cases may be due to additional genes resulting in a similar phenotype.

Identifying novel genetic determinants of hemostatic balance

Incomplete penetrance and variable expressivity confound the diagnosis and therapy of most inherited thrombotic and hemorrhagic disorders. For many of these diseases, some or most of this variability is determined by genetic modifiers distinct from the primary disease gene itself. Clues toward identifying such modifier genes may come from studying rare Mendelian disorders of hemostasis. Examples include identification of the cause of combined factor V and VIII deficiency as mutations in the ER Golgi intermediate compartment proteins LMAN1 and MCFD2. These proteins form a cargo receptor that facilitates the transport of factors V and VIII, and presumably other proteins, from the ER to the Golgi. A similar positional cloning approach identified ADAMTS-13 as the gene responsible for familial TTP. Along with the work of many other groups, these findings identified VWF proteolysis by ADAMTS-13 as a key regulatory pathway for hemostasis. Recent advances in mouse genetics also provide powerful tools for the identification of novel genes contributing to hemostatic balance. Genetic studies of inbred mouse lines with unusually high and unusually low plasma VWF levels identified polymorphic variation in the expression of a glycosyltransferase gene, Galgt2, as an important determinant of plasma VWF levels in the mouse. Ongoing studies in mice genetically engineered to carry the factor V Leiden mutation may similarly identify novel genes contributing to thrombosis risk in humans.

Combined factor V and factor VIII deficiency in a Thai patient: a case report of genotype and phenotype characteristics

A Thai woman, with no family history of bleeding disorders, presented with excessive bleeding after minor trauma and tooth extraction. The screening coagulogram revealed prolonged activated partial thromboplastin time and prothrombin time. The specific-factor assay confirmed the diagnosis of combined factor V and factor VIII deficiency (F5F8D). Her plasma levels of factor V and factor VIII were 10% and 12.5% respectively. The medications and blood product treatment to prevent bleeding from invasive procedure included 1-deamino-8-d-arginine vasopressin, cryoprecipitate, factor VIII concentrate, fresh frozen plasma and antifibrinolytic agent. Gene analysis of the proband identified two LMAN1 gene mutations; one of which is 823-1 G --> C, a novel splice acceptor site mutation that is inherited from her father, the other is 1366 C --> T, a nonsense mutation that is inherited from her mother. Thus, the compound heterozygote of these two mutations in LMAN1 cause combined F5F8D.

Recessively inherited coagulation disorders

Deficiencies of coagulation factors other than factor VIII and factor IX that cause bleeding disorders are inherited as autosomal recessive traits and are rare, with prevalences in the general population varying between 1 in 500 000 and 1 in 2 million for the homozygous forms. As a consequence of the rarity of these deficiencies, the type and severity of bleeding symptoms, the underlying molecular defects, and the actual management of bleeding episodes are not as well established as for hemophilia A and B. We investigated more than 1000 patients with recessively inherited coagulation disorders from Italy and Iran, a country with a high rate of recessive diseases due to the custom of consanguineous marriages. Based upon this experience, this article reviews the genetic basis, prevalent clinical manifestations, and management of these disorders. The steps and actions necessary to improve the condition of these often neglected patients are outlined.

Familial multiple coagulation factor deficiencies: new biologic insight from rare genetic bleeding disorders

Combined deficiency of factor (F)V and FVIII (F5F8D) and combined deficiency of vitamin K-dependent clotting factors (VKCFD) comprise the vast majority of reported cases of familial multiple coagulation factor deficiencies. Recently, significant progress has been made in understanding the molecular mechanisms underlying these disorders. F5F8D is caused by mutations in two different genes (LMAN1 and MCFD2) that encode components of a stable protein complex. This complex is localized to the secretory pathway of the cell and likely functions in transporting newly synthesized FV and FVIII, and perhaps other proteins, from the ER to the Golgi. VKCFD is either caused by mutations in the gamma-carboxylase gene or in a recently identified gene encoding the vitamin K epoxide reductase. These two proteins are essential components of the vitamin K dependent carboxylation reaction. Deficiency in either protein leads to under-carboxylation and reduced activities of all the vitamin K-dependent coagulation factors, as well as several other proteins. The multiple coagulation factor deficiencies provide a notable example of important basic biological insight gained through the study of rare human diseases.

The rare coagulation disorders - review with guidelines for management from the United Kingdom Haemophilia Centre Doctors' Organisation

The rare coagulation disorders are heritable abnormalities of haemostasis that may present significant difficulties in diagnosis and management. This review summarizes the current literature for disorders of fibrinogen, and deficiencies of prothrombin, factor V, FV + VIII, FVII, FX, the combined vitamin K-dependent factors, FXI and FXIII. Based on both collective clinical experience and the literature, guidelines for management of bleeding complications are suggested with specific advice for surgery, spontaneous bleeding, management of pregnancy and the neonate. We have chosen to include a section on Ehlers-Danlos Syndrome because haematologists may be consulted about bleeding manifestations in such patients.

Haemorrhagic symptoms in patients with combined factors V and VIII deficiency in north-eastern Iran

Of the six types of dual coagulation factors deficiency, combined factors V and VIII are the most common type, a few cases of this disease have been reported in different populations. This accounts for the relatively low number of cases reported so far. Our report, which included 19 patients, is the second largest group that has been reported from one centre in north-eastern Iran. The most frequent spontaneous bleeding symptoms were epistaxis and haemarthrosis, and the most frequent traumatic bleeding symptoms were bleeding after dental extraction and bleeding after cutting any part of the body. It seemed that dual coagulation FV and FVIII deficiency is as severe as single coagulation factor (V or VIII) deficiency.

A mutation in LMAN1 (ERGIC-53) causing combined factor V and factor VIII deficiency is prevalent in Jews originating from the island of Djerba in Tunisia

Combined deficiency of factor V and factor VIII is a rare autosomal recessive bleeding disorder that is caused by mutations in the LMAN1 or MCFD2 genes. These genes encode for proteins that form a complex that takes part in the transport of factor V and factor VIII from the endoplasmic reticulum to Golgi. Two mutations in LMAN1 have been observed in Jews: a guanine (G) insertion in exon 1 among Middle Eastern Jewish families, and a thymidine (T) to cytosine (C) transition in intron 9 at a donor splice site among Tunisian families. For each mutation, haplotype analysis revealed a founder effect. Because all affected Tunisian families belong to an ancient Jewish community in the island of Djerba off the coast of Tunisia, we screened members of this community for the intron 9 T --> C transition. Among 233 apparently unrelated individuals five heterozygotes were detected, predicting an allele frequency of 0.0107 (95% confidence interval, 0.0035-0.0248), while among 259 North African Jews none was found to carry the mutation. The prevalence of the mutation in Djerba Jews is consistent with the observation that all affected Tunisian Jewish families have origins in Djerba and with the finding of a common haplotype for the 9 + 2 T --> C mutation. The G insertion in exon 1 was found in one of 245 Iraqi Jews, predicting an allele frequency of 0.0022 (95% confidence interval, 0.0001-0.0123), but in none of 180 Iranian Jews examined. In view of the relatively low frequency of the mutations in the respective populations it seems reasonable to advocate carrier detection and prenatal diagnosis only in affected families.