Phenotypic and Genotypic Signatures of VWF Exon 18 in Eastern Saudi Patients Previously Diagnosed with Type 1 von Willebrand Disease

Abstract

Introduction von Willebrand disease (VWD) is the most prevalent bleeding disease, which is associated with either low levels of von Willebrand factor (VWF) or abnormality in its structure. Three types of the disease have been described; type 1 (VWD1) and 3 (VWD3) are caused by deficiency of VWF and type 2 (VWD2) is caused by production of defective VWF. The aim of the current study was to characterize gene variants of VWF gene; exon 18 in particular, in a cohort of Saudi families as well as healthy control subjects. Methods A total of 19 families comprising 60 subjects of type 1 VWD were enrolled in the study. Participants were divided into 22 index cases, 21 affected family members and 17 unaffected family members ranging in age from 6 to 70 years. Blood samples were collected from all participants to measure activated partial thromboplastin time test (APTT), von Willebrand antigen level (VWF:Ag), Factor VIII activity (FVIII:C) and ristocetin cofactor activity (VWF:RCo), platelet count, determining the ABO blood group and for genetic analysis by Sanger sequencing. Results The results indicated that VWD1 patients have lower levels of VWF and factor VIII than the non-affected family members and the control subjects. In addition, five gene variants were reported in VWF exon 18; of these, c.2365A>G and c.2385T>C were more common in the control group and might be protective from VWD. Discussion In conclusion, VWF levels are influenced by blood group, and there was no association between variants in exon 18 of VWF gene reported in all groups and the disease status; however, blood group analysis and genome-wide genotyping could help to highlight high-risk groups and improve clinical management of VWD.

Bleeding disorders in Saudi Arabia, causes and prevalence: a review

“…The genotypic and phenotypic signatures of exon 18 of the von Willebrand factor gene were investigated by another research (Alzahrani et al, 2022). Saudi patients, who also lived in the eastern province, have been diagnosed with type 1 vWD (type 1 vWD) were the participants of this study.…”

“…The correlation analysis in the control group showed no statistically significant correlation between the different genotypes and the level of expression of VWFAg, or VWF, factor VIII:RCo. Similarly, among healthy individuals, rs1063857 did not demonstrate any significant association with VWFAg, or VWF, factor VIII:RCo [ 7 ].…”

“…Several studies have identified specific genetic mutations that could lead to defective expression of coagulation factors giving the clinical presentations of hemophilia and other bleeding disorders among Saudis [ 7 ]. The constant evolution of molecular tools has enhanced diagnostic techniques as well as early detections improving therapeutic interventions [ 8 ].…”