biostudies-literatureFlood VHNHLBI NIH HHS2481-8https://www.ebi.ac.uk/biostudies/studies/S-EPMC4874228biostudies-literatureUnknown127(20)von Willebrand disease (VWD) is the most common inherited bleeding disorder, and type 1 VWD is the most common VWD variant. Despite its frequency, diagnosis of type 1 VWD remains the subject of debate. In order to study the spectrum of type 1 VWD in the United States, the Zimmerman Program enrolled 482 subjects with a previous diagnosis of type 1 VWD without stringent laboratory diagnostic criteria. von Willebrand factor (VWF) laboratory testing and full-length VWF gene sequencing was performed for all index cases and healthy control subjects in a central laboratory. Bleeding phenotype was characterized using the International Society on Thrombosis and Haemostasis bleeding assessment tool. At study entry, 64% of subjects had VWF antigen (VWF:Ag) or VWF ristocetin cofactor activity below thBloodClinical and laboratory variability in a cohort of patients diagnosed with type 1 VWD in the United States.PMC4874228R01 HL112614K08 HL102260P01 HL081588Hoots WKPeake IRHoffmann RGShapiro ADManco-Johnson MJFlood VHUdani RAChristopherson PALeissinger CLentz SRLillicrap DMontgomery KTAbshire TCBellissimo DBFriedman KDDasgupta MJames PDRagni MVBoggio LNGoodeve ACHaberichter SLMontgomery RRLusher JMGill JCGruppo RAfalseClinical and laboratory variability in a cohort of patients diagnosed with type 1 VWD in the United States.von Willebrand disease (VWD) is the most common inherited bleeding disorder, and type 1 VWD is the most common VWD variant. Despite its frequency, diagnosis of type 1 VWD remains the subject of debate. In order to study the spectrum of type 1 VWD in the United States, the Zimmerman Program enrolled 482 subjects with a previous diagnosis of type 1 VWD without stringent laboratory diagnostic criteria. von Willebrand factor (VWF) laboratory testing and full-length VWF gene sequencing was performed for all index cases and healthy control subjects in a central laboratory. Bleeding phenotype was characterized using the International Society on Thrombosis and Haemostasis bleeding assessment tool. At study entry, 64% of subjects had VWF antigen (VWF:Ag) or VWF ristocetin cofactor activity below th2016-01-01T00:00:00Z2016 May2025-06-01T04:17:46.504Z2019-06-06T15:50:11ZS-EPMC48742282686211010.1182/blood-2015-10-673681