INTRODUCTION: Type 3 von Willebrand disease (VWD), a severe autosomal recessive hereditary bleeding disorder, is described by the virtual absence of von Willebrand factor (VWF). In consanguineous populations, for example Pakistan, the disease is reported with a higher incidence rate than the worldwide prevalence. AIMS: This study aims to characterize molecular pathology and clinical profile of type 3 VWD cohort of Pakistani origin. METHODS: In total, 48 patients were enrolled in the current study. Initially, the index patients (IPs) were evaluated by a standardized questionnaire for recording bleeding manifestations and by performing conventional coagulation tests. The diagnosis of VWD type 3 was confirmed by VWF antigens less than 5 IU/dL. Direct sequencing of VWF gene (VWF) was carried out to identify causative gene variations. We evaluated the potential consequence of novel splice site and missense variations by predictive computational programs and in silico structural analysis. RESULTS: VWF mutations were detected in 46 out of 48 IPs (95.8%), predominantly as homozygous variants. In total, twenty-nine different gene defects were characterized in this cohort from which 10 (34.5%) are novel. The majority of the mutations were null alleles (66%; including gene conversions, nonsense, splice site variations, small deletions and insertions), and 34% of them were missense substitutions. CONCLUSION: Herein, we reported for the first time, the pattern of gene defects in Pakistani type 3 VWD cohort. We identified a wide heterogeneous mutation spectrum along with variability in the type of bleeding episodes.
INTRODUCTION: Type 3 von Willebrand disease (VWD), a severe autosomal recessive hereditary bleeding disorder, is described by the virtual absence of von Willebrand factor (VWF). In consanguineous populations, for example Pakistan, the disease is reported with a higher incidence rate than the worldwide prevalence. AIMS: This study aims to characterize molecular pathology and clinical profile of type 3 VWD cohort of Pakistani origin. METHODS: In total, 48 patients were enrolled in the current study. Initially, the index patients (IPs) were evaluated by a standardized questionnaire for recording bleeding manifestations and by performing conventional coagulation tests. The diagnosis of VWD type 3 was confirmed by VWF antigens less than 5 IU/dL. Direct sequencing of VWF gene (VWF) was carried out to identify causative gene variations. We evaluated the potential consequence of novel splice site and missense variations by predictive computational programs and in silico structural analysis. RESULTS:VWF mutations were detected in 46 out of 48 IPs (95.8%), predominantly as homozygous variants. In total, twenty-nine different gene defects were characterized in this cohort from which 10 (34.5%) are novel. The majority of the mutations were null alleles (66%; including gene conversions, nonsense, splice site variations, small deletions and insertions), and 34% of them were missense substitutions. CONCLUSION: Herein, we reported for the first time, the pattern of gene defects in Pakistani type 3 VWD cohort. We identified a wide heterogeneous mutation spectrum along with variability in the type of bleeding episodes.
Authors: Luciano Baronciani; Ian Peake; Reinhard Schneppenheim; Anne Goodeve; Minoo Ahmadinejad; Zahra Badiee; Mohammad-Reza Baghaipour; Olga Benitez; Imre Bodó; Ulrich Budde; Andrea Cairo; Giancarlo Castaman; Peyman Eshghi; Jenny Goudemand; Wolf Hassenpflug; Hamid Hoorfar; Mehran Karimi; Bijan Keikhaei; Riitta Lassila; Frank W G Leebeek; Maria Fernanda Lopez Fernandez; Pier Mannuccio Mannucci; Renato Marino; Nikolas Nikšić; Florian Oyen; Cristina Santoro; Andreas Tiede; Gholamreza Toogeh; Alberto Tosetto; Marc Trossaert; Eva M K Zetterberg; Jeroen Eikenboom; Augusto B Federici; Flora Peyvandi Journal: Blood Adv Date: 2021-08-10