[Von Willebrand disease. Molecular biology and diagnosis]

Genetic and Bioinformatic Strategies to Improve Diagnosis in Three Inherited Bleeding Disorders in Bogotá, Colombia

Inherited bleeding disorders (IBDs) are the most frequent congenital diseases in the Colombian population; three of them are hemophilia A (HA), hemophilia B (HB), and von Willebrand Disease (VWD). Currently, diagnosis relies on multiple clinical laboratory assays to assign a phenotype. Due to the lack of accessibility to these tests, patients can receive an incomplete diagnosis. In these cases, genetic studies reinforce the clinical diagnosis. The present study characterized the molecular genetic basis of 11 HA, three HB, and five VWD patients by sequencing the F8, F9, or the VWF gene. Twelve variations were found in HA patients, four in HB patients, and 19 in WVD patients. From these variations a total of 25 novel variations were found. Disease-causing variations were used as positive controls for validation of the high-resolution melting (HRM) variant-scanning technique. This approach is a low-cost genetic diagnostic method proposed to be incorporated in developing countries. For the data analysis, we developed an accessible open-source code in Python that improves HRM data analysis with better sensitivity of 95% and without bias when using different HRM equipment and software. Analysis of amplicons with a length greater than 300 bp can be performed by implementing an analysis by denaturation domains.

Von Willebrand Disease type 2 in pregnancy - A critical clinical association

Von Willebrand disease (vWD) is the most common inherited bleeding disorder. Its association with pregnancy is infrequent. Here we report three cases of vWD associated with pregnancy. The clinical features of this combination are very suggestive. However, difficulties are still encountered during the diagnosis process. The first case was diagnosed for the first time during the patient's second pregnancy despite several episodes of vaginal bleeding and suggestive clinical symptomatology. The second case was diagnosed during childhood and the patient was properly managed during this pregnancy. The third case was diagnosed at a pre-anesthesia consult, at 36 weeks gestation, before performing a cesarean section on request, despite a clinical suggestive symptomatology. All of the cases received prophylactic treatment with Haemate P^® (CSL Behring, Marburg, Germay) 24hours before birth. No serious bleeding episodes were noticed during delivery or postpartum period. Two healthy babies were delivered from the cases Nos. 2 and 3. It is acknowledged that vaginal bleeding is common during first trimester of pregnancy. However, this study indicates that repeated bleeding episodes corroborated with a clinical suggestive symptomatology (epistaxis, heavy menstrual period, and easy bruising after minor trauma) should orient the diagnosis to vWD.