MicroRNA Prediction in the FVIII Gene Locus: A Step Towards Hemophilia A Control

Background: Various mutations in factor VIII (F8) gene locus are led to an X-linked bleeding disorder in patients with hemophilia A. One of the leading causes of inefficient treatment available for hemophilia A is the lack of specific and sensitive diagnostic procedure for the disease. The discovery of a functional role of microRNAs (miRNAs) in the pathogenesis of a wide range of human diseases makes them the potential, non-invasive, biomarker candidates for hemophilia A. Therefore, advances in computational tools for miRNA discovery leads to numerous recent publications on miRNAs as putative biomarkers. Objectives: The current study aimed at scanning the F8 gene region to predict novel miRNAs as regulators of the F8 gene. Methods: The potential of the FVIII locus to express new miRNAs was studied via reliable bioinformatics databases, such as SSCprofiler, RNAfold, miREval, miR-Find, FOMmiR, UCSC genome browser, and miRBase. Results: Data analysis from previously mentioned databases offered two stem-loop structures predicted to express novel miRNAs. Conclusions: The presented stem-loop structures can be used as powerful non-invasive biomarkers in early diagnosis of the disease and regulation of the factor VIII gene after subsequent experimental verification.

A Closed-Tube Nested Quantitative PCR Assay for Rapid Detection of Intron 22 Inversions in the Factor VIII Gene

Background An inversion of intron 22 in the Factor VIII gene (Inv22) is the causative mutation for 45% of severe hemophilia A cases. Available methods for molecular diagnosis of Inv22 are generally tedious and not ideal for routine clinical use. Methods We report here a new method using a single closed-tube nested quantitative PCR (CN–qPCR) for rapid detection of Inv22. This method combines a 12-cycle long-distance PCR (LD–PCR) amplifying the int22h regions, followed by a duplex qPCR targeting two specific regions close to the int22h regions. All reagents were added to a single PCR mixture for the closed-tube assay. Sequential LD–PCR and qPCR was achieved by designing primers at substantially different melting temperatures and optimizing PCR conditions. Results Seventy-nine male hemophilia A patients of different disease severity were tested by both the CN–qPCR assay and the standard LD–PCR assay. CN–qPCR successfully made calls for all samples, whereas LD–PCR failed in eight samples. For the 71 samples where both methods made calls, the concordance was 100%. Inv22 was detected in 17 out of the 79 samples. Additionally, CN–qPCR achieved clear separation for 10 female carriers and 10 non-Inv22 females, suggesting the assay may also be useful for molecular diagnosis of female carriers. Conclusions This new CN–qPCR method may provide a convenient and accurate F8 Inv22 test suitable for clinical use.

Identification of the Intron 22 and Intron 1 Inversions of the Factor VIII Gene in Iraqi Kurdish Patients With Hemophilia A

Hemophilia A (HA) is a severe coagulation disorder affecting 1 in 5000 to 10 000 male births. In severe cases, the most deleterious large DNA rearrangements are inversions of intron 22 (Inv22) and intron 1 (Inv1) of the factor VIII (FVIII) gene. These account for 40% to 50% and 1% to 5% of all causative mutations, respectively. Nevertheless, no genetic analysis to identify the actual causative mutation of FVIII, particularly Inv22 and Inv1, among Iraqi Kurdish hemophiliacs has been performed. In this study, we aimed to genotype Inv22 and Inv1 of the FVIII gene in our patients with HA and reveal the genotype/phenotype correlation with the inversion mutations and their role as a risk factor for the development of inhibitors. Analyses of the Inv22 and Inv1 mutations in 80 Iraqi Kurdish patients with HA (60 severe, 18 moderate, and 2 mild) were performed using the inverse shifting–polymerase chain reaction (IS-PCR) method. In severe cases, 46.7% (28/60) had Inv22 and 3.3% (2/60) had Inv1. The genotype/phenotype relation of Inv22 and Inv1 illustrated a statistically significant association ( P = .012) between disease severity and inversion mutations. Slightly more patients with Inv22 (39%) developed inhibitors than those without Inv22 (28%; odds ratio = 1.65, 95% confidence interval = 0.56-4.87, P = .361). Inv22 is a major cause of severe HA in Iraqi Kurdish patients, and IS-PCR is a rapid, robust, and effective method that can be applied for carrier detection and prenatal diagnosis of HA in developing countries.

Application of Indirect Linkage Analysis for Carrier Detection of Hemophilia A in Kurdistan Region of Iraq: Usefulness of Intron 18 BclI T>A, Intron 19 HindIII C>T, and IVS7 nt27 G>A Markers

Hemophilia A (HA) is the most common congenital X-linked coagulopathy caused by mutations in the factor VIII gene. One in 5000 to 10 000 male persons worldwide suffer from HA. It is the archetype of high-cost, low-volume disease. Therefore, identification of carriers is crucial to avoid the birth of affected males. Tracking of the defective X chromosome through indirect linkage analysis represents the most practical method for screening for carriers in developing countries. In this study, 227 individuals from 41 families with HA and 100 normal participants were recruited from the Kurdistan region of Iraq and evaluated for intron 18 BclI, intron 19 HindIII, and IVS7 nt 27 markers by polymerase chain reaction restriction fragment length polymorphism and direct sequencing. Among the studied women, 49%, 42%, and 14% were discovered to be heterozygous for BclI, HindIII, and IVS7 markers, respectively. Using BclI, HindIII, and IVS7 markers, 56%, 46%, and 17% of the families were informative, respectively. The combined informativity of these polymorphic sites reaches 66%. The current study illustrates the effectiveness of the BclI and HindIII markers for the diagnosis of HA carriers among the Iraqi Kurdish population.

Case Report: Development of Factor VIII Inhibitor in a Patient with an Uncommon de novo Mutation in the Factor VIII Gene

The development of factor VIII inhibitors remains a significant clinical challenge in the management of hemophilia A. We present a patient of mixed ethnicity with severe hemophilia A who was found to have a F8 gene hemizygous c.5815G>T mutation resulting in an Ala1939Ser substitution (Ala1920Ser in legacy nomenclature) and possible splice site change that has been reported in only 1 patient previously. He developed an inhibitor shortly after starting replacement recombinant factor VIII (Advate®; Baxalta, Bannockburn, IL, USA) and was successfully treated with immune tolerance therapy. Our report describes the second patient reported to have severe hemophilia due to this mutation and the only case of a factor VIII inhibitor associated with this mutation.