Genotypes and phenotypes characterization of 17 Iranian patients with inherited factor X deficiency: identification of a novel mutation: Leu487Phe

Factor X deficiency is a rare bleeding disorder that affects almost 1 : 1000 000 people worldwide. It derives from multiple mutational changes in the factor X gene (F10). The main objective of the present study was to determine a consistent correlation between the clinical presentations and causative genotype. The phenotype and genotype of 17 Iranian patients with reduced factor X activity (FX:C) from 14 unrelated families were analyzed to screen factor X gene expression for any possible mutations and function alteration. Analysis of the sequencing results led to the identification of eight different mutations besides a single nucleotide variation. One of the mutations was novel (Leu487Phe) as studied by means of online analysis programs and molecular modeling. Eight patients were homozygote; three were heterozygote, while six out of 17 patients were symptomatic cases without any mutations. The Arg40Thr missense mutation was detected in three patients including two siblings and was associated with severe bleeding symptoms. Also, two patients were identified with Gly262Asp missense mutation which commonly presented with bleeding disorder. Each of the other patients was associated with a unique missense mutation including one novel mutation in which the tentative relation of the mutation to bleeding symptoms is reported. Mutations leading to a FX:C of less than 1% are associated with severe bleeding symptoms confirming the strong correlation between clinical severity and FX:C. The novel Leu487Phe mutation with FX:C of 13% may have possible negative effects on factor X protein function resulting in minor clinical manifestation.

Rare Coagulation Factor Deficiencies (Factors VII, X, V, and II)

Although rare clotting factor deficiencies primarily referred to as rare bleeding disorders (RBD), including factors II, V, VII, and X, make up ∼5% of all inherited bleeding disorders worldwide, each of these clotting factors play a critical role in the coagulation cascade. Incomplete bleeding evaluation or misinterpretation of laboratory studies can result in delayed diagnoses that ultimately affect patient outcomes. Bleeding manifestations can range from mild to severe, but the most common are mucocutaneous bleeding. The ideal treatment in RBD is dedicated single-factor concentrates that can be used for acute bleeding events, surgical management, and prophylaxis.

Diagnosis, therapeutic advances, and key recommendations for the management of factor X deficiency

Factor X deficiency is a rare coagulation disorder that can be hereditary or acquired. The typology and severity of the associated bleeding symptoms are highly heterogeneous, adding to the difficulties of diagnosis and management. Evidence-based guidelines and reviews on factor X deficiency are generally limited to publications covering a range of rare bleeding disorders. Here we provide a comprehensive review of the literature on factor X deficiency, focusing on the hereditary form, and discuss the evolution in disease management and the evidence associated with available treatment options. Current recommendations advise clinicians to use single-factor replacement therapy for hereditary disease rather than multifactor therapies such as fresh frozen plasma, cryoprecipitate, and prothrombin complex concentrates. Consensus in treatment guidelines is still urgently needed to ensure optimal management of patients with factor X deficiency across the spectrum of disease severity.

Complex formation with pentraxin-2 regulates factor X plasma levels and macrophage interactions

We have identified PTX2 as a novel partner for FX in the circulation, and their plasma levels are interdependent. FX and PTX2 cooperate with SR-AI to prevent their uptake by macrophages.

Bleeding manifestations in heterozygotes with congenital FVII deficiency: a comparison with unaffected family members during a long observation period

OBJECTIVES

To determine whether heterozygotes with FVII deficiency have a bleeding tendency or not.

PATIENTS AND METHODS

Eighty-four patients (OK) heterozygous for FVII deficiency, at the onset of the study, were paired with unaffected family members and followed for a long period of time (mean 22.6 years) for the occurrence of bleeding. Diagnosis of heterozygosis had to be based on family studies, clotting, immunological assays and genetic analysis.

RESULTS

The mean FVII activity level was 0.51 IU/dl (range 35-65) and 94 IU/dl (range 88-118) in the heterozygotes and in the normal counterparts, respectively. Documented bleeding manifestations occurred in eight heterozygotes and in seven normal subjects. Statistical analysis of the difference was not significant. Bleeding manifestations were easy bruising, bleeding after tooth extractions, menorrhagia, epistaxis with no difference among the two groups. There was no strict correlation between bleeding and FVII activity levels.

CONCLUSIONS

The study indicates that heterozygotes for FVII deficiency show rare bleeding manifestations which are also present in the unaffected family members with normal FVII levels. This indicates that Factor VII activity levels played no role in the occurrence of the bleeding symptoms. Furthermore, FVII levels of around 0.40 IU/dl are capable of assuring a normal hemostasis.