von Willebrand factor propeptide and the phenotypic classification of von Willebrand disease

UNLABELLED: The ratios between von Willebrand factor propeptide (VWFpp) or factor VIII activity (\n\nFVIII: C) and VWF antigen (VWF:Ag) reflect synthesis, secretion, and clearance of VWF. We aimed to define the pathophysiology of 658 patients with type 1, 2, or 3 von Willebrand disease (VWD) with VWF levels ≤30 U/dL from the Willebrand in The Netherlands (WiN) study using the VWFpp/VWF:Ag and\n\nFVIII: C/VWF:Ag ratios. We evaluated the use of VWFpp in the classification and diagnosis of VWD. On the basis of the ratios, reduced VWF synthesis was observed in 18% of type 1 and only 2% of type 2 patients. A significant proportion of type 3 patients had detectable VWFpp (41%). These patients had a lower bleeding score than type 3 patients who had a complete absence of VWF:Ag and VWFpp (14.0 vs 19.5; P = .025). The majority of these patients had missense mutations with rapid VWF clearance, whereas type 3 patients with no VWFpp were homozygous for null alleles. In conclusion, VWFpp identified severe type 1 VWD with very low VWF levels in patients who had previously been classified as type 3 VWD. This study underlines the clinical significance of the VWFpp assay in the diagnosis and classification of VWD

Von Willebrand disease and aging: An evolving phenotype

BACKGROUND: Because the number of elderly von Willebrand disease (VWD) patients is increasing, the pathophysiology of aging in VWD has become increasingly relevant. OBJECTIVES: To assess age-related changes in von Willebrand factor (VWF) and factor VIII (FVIII) levels and to compare age-related differences in bleeding phenotype between elderly VWD patients and those <65 years. We also studied co-morbidity in elderly patients. PATIENTS/METHODS: We included VWD patients with VWF levels ≤ 30 U dL(-1) in the nationwide cross-sectional 'Willebrand in the Netherlands' (WiN-) study. Patients reported bleeding episodes and treatment of VWD in the year preceding inclusion and during life. This was compared between VWD patients older (n = 71) and younger (16-64 years, n = 593) than 65 years. In elderly patients, age-related changes in VWF and FVIII levels were studied longitudinally by including all historically measured levels. All medical records were examined for co-morbidity. RESULTS: In elderly type 1 patients, a decade age increase was associated with a 3.5 U dL(-1) (95% CI, -0.6 to 7.6) VWF:Ag increase and 7.1 U dL(-1) (95% CI, 0.7 to 13.4) FVIII:C increase. This increase was not observed in elderly type 2 patients. Elderly type 2 patients reported significantly more bleeding symptoms in the year preceding inclusion than younger patients (16/27, 59% vs. 87/221, 39%; P = 0.048), which was not observed in type 1 VWD. CONCLUSIONS: von Willebrand factor parameters and bleeding phenotype evolve with increasing age in VWD. VWF and FVIII levels increase with age in type 1 patients with no mitigation in bleeding phenotype. In type 2 patients VWF parameters do not increase with age and in these patients aging is accompanied by increased bleeding

A promoter-level mammalian expression atlas

Regulated transcription controls the diversity, developmental pathways and spatial organization of the hundreds of cell types that make up a mammal. Using single-molecule cDNA sequencing, we mapped transcription start sites (TSSs) and their usage in human and mouse primary cells, cell lines and tissues to produce a comprehensive overview of mammalian gene expression across the human body. We find that few genes are truly ‘housekeeping’, whereas many mammalian promoters are composite entities composed of several closely separated TSSs, with independent cell-type-specific expression profiles. TSSs specific to different cell types evolve at different rates, whereas promoters of broadly expressed genes are the most conserved. Promoter-based expression analysis reveals key transcription factors defining cell states and links them to binding-site motifs. The functions of identified novel transcripts can be predicted by coexpression and sample ontology enrichment analyses. The functional annotation of the mammalian genome 5 (FANTOM5) project provides comprehensive expression profiles and functional annotation of mammalian cell-type-specific transcriptomes with wide applications in biomedical research