The diagnosis of von Willebrand disease (VWD) remains difficult in a significant proportion of patients. A Spanish multicentre study investigated a cohort of 556 patients from 330 families who were analysed centrally. VWD was confirmed in 480. Next generation sequencing (NGS) of the whole coding VWF was carried out in all recruited patients, compared with the phenotype, and a final diagnosis established. A total of 238 different VWF mutations were found, 154 were not included in the Leiden Open Variation Database (LOVD). Of the patients, 463 were found to have VWF mutation/s. A good phenotypic/genotypic association was estimated in 96.5% of the patients. One hundred seventy-four patients had two or more mutations. Occasionally a predominant phenotype masked the presence of a second abnormality. One hundred sixteen patients presented with mutations that had previously been associated with increased von Willebrand factor (VWF) clearance. RIPA unavailability, central phenotypic results disagreement and difficult distinction between severe type 1 and type 3 VWD prevented a clear diagnosis in 70 patients. The NGS study facilitated an appropriate classification in 63 of them. The remaining seven patients presented with a VWF novel mutation pending further investigation. In five patients with a type 3 and two with a type 2A or 2B phenotype with no mutation, an acquired von Willebrand syndrome (AVWS) was suspected/confirmed. These data seem to support NGS as a first line efficient and faster paradigm in VWD diagnosis.

Molecular diagnosis of patients with von Willebrand disease is pending in most populations due to the complexity and high cost of conventional molecular analyses. The need for molecular and clinical characterization of von Willebrand disease in Spain prompted the creation of a multicenter project (PCM-EVW-ES) that resulted in the largest prospective cohort study of patients with all types of von Willebrand disease. Molecular analysis of relevant regions of the VWF, including intronic and promoter regions, was achieved in the 556 individuals recruited via the development of a simple, innovative, relatively low-cost protocol based on microfluidic technology and next-generation sequencing. A total of 704 variants (237 different) were identified along VWF, 155 of which had not been previously recorded in the international mutation database. The potential pathogenic effect of these variants was assessed by in silico analysis. Furthermore, four short tandem repeats were analyzed in order to evaluate the ancestral origin of recurrent mutations. The outcome of genetic analysis allowed for the reclassification of 110 patients, identification of 37 asymptomatic carriers (important for genetic counseling) and re-inclusion of 43 patients previously excluded by phenotyping results. In total, 480 patients were definitively diagnosed. Candidate mutations were identified in all patients except 13 type 1 von Willebrand disease, yielding a high genotype-phenotype correlation. Our data reinforce the capital importance and usefulness of genetics in von Willebrand disease diagnostics. The progressive implementation of molecular study as the first-line test for routine diagnosis of this condition will lead to increasingly more personalized and effective care for this patient population.

Aim The use of musculoskeletal ultrasound (MSK‐US) following protocols for haemophilic arthropathy and the Haemophilia Early Arthropathy Detection with Ultrasound (HEAD‐US) score can help standardize monitoring in haemophilia. This study evaluated the joint status (elbows, knees and ankles) of patients with haemophilia B (HB) in Spain using MSK‐US and the HEAD‐US score. Methods Haemophilia B patients ≥14 years old were included in this observational, multicentre, cross‐sectional study, regardless of their clinical condition, HB severity and treatment received. Two blinded observers were involved in image acquisition and scoring in each centre. Results Eighty‐two patients from 12 centres were enrolled: 27% mild HB, 23% moderate, 50% severe HB. Mean age was 38.9 ± 16.4 years, 60% were treated on demand (OD) and 40% were on prophylaxis. HEAD‐US was zero in all joints in 28.6% OD patients and 36.4% on prophylaxis. Mean scores significantly worsened with HB severity, except for the left knee. Patients on primary and secondary prophylaxis had significantly better joint health vs OD patients in all joints, except the right ankle. Among OD patients, those with severe disease presented significantly worse scores in all HEAD‐US items related to permanent damage. Conclusion Joint status of HB patients in Spain is influenced by severity and treatment modality, related to the development of arthropathy, which appears prevalent in OD patients with severe HB. Routine assessment with an imaging tool such as ultrasound and HEAD‐US system may help to improve joint health by personalizing and adjusting treatment in this population.

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