VWF:Ag levels by ethnicity and blood type. Normal controls were enrolled in the ZPMCB-VWD and separated by self-reported race or ethnicity. The racial and ethnic groups are African American (AA), Caucasian American (CA), Hispanic American (HA), and Asian American (AsA) and are divided by blood type (O vs non-O). In all cohorts type O individuals had significantly lower VWF:Ag, with the most striking difference in AsA, with mean VWF:Ag of 66 in blood group O and 109 in non-O. A total of 33% of AsAs had VWF:Ag levels below the normal range (dashed line represents the upper and lower limits of VWF:Ag).