Genetic Background of Patients With Low Von Willebrand Factor Levels
- Conditions
- Low Von Willebrand Factor
- Interventions
- Diagnostic Test: Whole-exome sequencing
- Registration Number
- NCT05116501
- Brief Summary
Von Willebrand disease (VWD) is caused by either quantitative or qualitative von Willebrand (VWF) defects and is the commonest inherited bleeding disorder with an estimated prevalence of about 1% in the general population. According to several guidelines, patients with a mild quantitative reduction in VWF (30-50 IU/dL) should be labeled as "low VWF". Quantitatively VWF defects account for almost 75% of all cases with VWD and among them, low VWF seems to be the most common form. Studies on patients with VWD reported only around 50% VWF mutations in low VWF cases indicating that some possible genes outside of the VWF gene may be responsible for the low VWF levels. To date, using genome-wide association study (GWAS) more than 19 non-VWF loci (such as ABO blood group system, Stabilin 2, Scavenger Receptor Class A Member 5, C-Type Lectin Domain Family 4 Member M, etc.) were identified to be associated with VWF levels. The identified genes are related to different mechanisms of the VWF life-cycle such as synthesis, secretion, glycosylation, or clearance. Despite the importance of the genetic background of low VWF levels for understanding its etiology, this issue is not well investigated yet. Thus the Low VWF Milan Cohort (LOVMIC) Study is designed to address some unanswered questions in patients with low VWF.
- Detailed Description
Despite the absence of mutation in the VWF gene in a significant number of individuals with reduced VWF levels and also the lack of knowledge for the responsible mechanisms, this study sought to determine the following goals:
* Evaluation of the genetic background of low VWF level dilemma and identifying the gene (s) outside of the VWF gene that is associated with decreased VWF levels.
* Evaluating the correlation between candidate variants and patients' bleeding manifestations.
Study design:
Non-pharmacological Interventional National Monocentric Study. Promoter: Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Coordinating center and patient recruitment unit: Department of General Medicine - Hemostasis and Thrombosis - Angelo Bianchi Bonomi Hemophilia and Thrombosis Center
Setting: outpatients' clinic
The study population will be selected from the referral adult patients/healthy controls to the A. Bianchi Bonomi Hemophilia and Thrombosis Center in Fondazione IRCCS Ca' Granda Maggiore Policlinic hospital.
Recruiting method:
Selected patients (base on the previous laboratory results) will be invited to participate in the study by physicians at the center through phone calls. Also, normal controls (age- and sex-matched with patients) will be enrolled in the study. Data regarding the healthy controls will be obtained either from the available public database or obtained by evaluation of collected samples from the normal subjects who have been selected by the A. Bianchi Bonomi Hemophilia and Thrombosis Center.
Enrolment, visit, and blood samples collection:
Following the agreement of patients for participating in the study and signing the informed consent, 3 tubes (each 3.5 ml) of the blood sample will be collected for performing VWD-related laboratory tests (VWF antigen (VWF:Ag), VWF ristocetin cofactor (VWF:RCo), Factor VIII clotting assay (FVIII:C)) and Whole-exome sequencing (WES). In addition, a routinely clinical examination will be done by specialized physicians, according to a Case Report Form (CRF) to collect the data regarding age, sex, blood group, and clinical manifestations including the International Society on Thrombosis and Haemostasis Bleeding Assessment Tool (ISTH-BAT).
Genetic analysis:
* Genomic DNA will be extracted using the automated instrument from QIAGEN available in the central genetic laboratory at the Fondazione IRCCS Ca' Granda Maggiore Policlinic hospital
* WES will be performed on all samples using NextSeq 2000 instrument in the central genetic laboratory at the Fondazione IRCCS Ca' Granda Maggiore Policlinic hospital.
* Data will be analyzed following the same strategy in both cases and controls. First, the VWF gene will be evaluated. Then, the analysis will be extended to the other genes that were previously described as related to VWF level variations. Lastly, exome data will be considered.
* The association between VWF levels and candidate variants will be assessed.
* All analyses will be performed considering variants' minor allele frequency (MAF), age, sex, ABO to control for confounding.
Recruitment & Eligibility
- Status
- UNKNOWN
- Sex
- All
- Target Recruitment
- 300
Not provided
- Pregnant women
- Patients with acquired von Willebrand disease syndrome
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- SINGLE_GROUP
- Arm && Interventions
Group Intervention Description low VWF Whole-exome sequencing In patients with low VWF levels, whole-exome sequencing will be performed to identity possible variants in the VWF gene or other genes that are associated with reduced VWF plasma levels. Furthermore, a correlation study between variants identified and the bleeding symptoms of patients will be performed. Healthy controls Whole-exome sequencing In healthy controls, the investigators will analyze the whole-exome sequencing to include the variants that are either not present in healthy controls or are present but with a significantly lower frequency than the patients.
- Primary Outcome Measures
Name Time Method Genetic variants in the VWF gene or other genes associated with low VWF plasma levels 8 months after starting the project More than 19 different genes have been identified by genome-wide association studies that affect the plasma VWF levels. These genes (in addition to VWF) are including STXBP5, SCARA5, ABO, STAB2, STX2, TCN2, CLEC4M, PDHB/PXK/KCTD6, SLC39A8, FCHO2/TMEM171/TNPO1, HLA, GIMAP7/GIMAP4, OR13C5/NIPSNAP, DAB2IP, C2CD4B, RAB5C-KAT2A, TAB1/SYNGR1, and ARSA. Some studies showed an association between specific variants with a minor allele frequency (MAF) \> 10% and the reduction of VWF levels or severe clinical symptoms in patients with VWD.
As a primary outcome, whole-exome sequencing will be carried out in 300 subjects (150 patients and 150 healthy controls) to identify variants either in the VWF gene or the aforementioned genes or some new genes that are associated with reduced VWF levels in plasma.
- Secondary Outcome Measures
Name Time Method Correlation between the bleeding presentation and identified variants in patients with low VWF 12 months after starting the project As the second outcome, the association between the identified potential variants and patient bleeding manifestations will be evaluated. The ISTH-BAT is used to quantify bleeding symptoms.
Trial Locations
- Locations (1)
Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, A.B.Bonomi Hemophilia and Thrombosis Center
🇮🇹Milan, Lombardia, Italy