Sequence variation data of F8 and F9 genes in functionally validated control individuals: implications on the molecular diagnosis of hemophilia

Novel Mutations Resulting in a Moderate to Severe Phenotypic Manifestation of Hemophilia A in a Female

Hemophilia A is an X-linked, recessive disorder resulting from mutations in the f8 gene. Here we report the rare case of a female compound heterozygote with mild factor VIII deficiency (fVIII:C 9%) and moderate phenotype. On investigation she was confirmed to have normal Von Willebrand factor studies with a 46XY genotype. Further genetic testing revealed 3 mutations in the f8 gene: 1 novel missense mutation (c.6142T>G), 1 novel in-frame deletion (c.1281_1292del), and another missense mutation of unclear significance (c.3780C>G). Both parents had normal coagulation profiles; however, the 2 novel mutations were present in the patient's mother and the known missense mutation was present in her father. This unusual case demonstrates the utility in genetic analysis for f8 gene mutational analysis and suggests a compound effect of the 3 identified mutations as a cause for factor deficiency.

Personalized medicine and blood disorders

Personalized medicine has been using genomics approaches to elucidate the etiology of a disease as well as to personalize the management for patients of a particular disease based on that individual's genetic features. It benefits patients across a multitude of therapeutic areas and advancements are particularly evident in hematology/oncology. The importance of genomics discoveries and development in nonmalignant blood disorders generally goes unrecognized, but it becomes critical now due to the global disease burden and a high mortality. This paper focuses on the exploration of personalized medicine applications in hemoglobin diseases, and thrombotic and bleeding disorders. It discusses the challenges which slow down the implementation as well. The available data suggest that the ability to understand the clinical features of a patient's genetic profile and the knowledge of disease mechanisms are the keys to facilitate new diagnosis, new therapies, new prescriptions and better healthcare.

Human coagulation factor VIII domain-specific recombinant polypeptide expression

Background

Hemophilia A is caused by heterogeneous mutations in F8. Coagulation factor VIII (FVIII), the product of F8, is composed of multiple domains designated A1-A2-B-A3-C1-C2. FVIII is known to interact with diverse proteins, and this characteristic may be important for hemostasis. However, little is known about domain-specific functions or their specific binding partners.

Methods

To determine F8 domain-specific functions during blood coagulation, the FVIII domains A1, A2, A3, and C were cloned from Hep3B hepatocytes. Domain-specific recombinant polypeptides were glutathione S-transferase (GST)- or polyhistidine (His)-tagged, over-expressed in bacteria, and purified by specific affinity chromatography.

Results

Recombinant polypeptides of predicted sizes were obtained. The GST-tagged A2 polypeptide interacted with coagulation factor IX, which is known to bind the A2 domain of activated FVIII.

Conclusion

Recombinant, domain-specific polypeptides are useful tools to study the domain-specific functions of FVIII during the coagulation process, and they may be used for production of domain-specific antibodies.