Is it possible for someone who has been diagnosed as having Type 1 VWD and then later due to biochemistry receive a diagnosis of Type 3 VWD?

Making a diagnosis of VWD is difficult and the difference between severe type 1 and type 3 can be difficult to establish with previous testing only, and really difficult if no genetic testing was performed. The bottom line is the type does not change just our ability to discern them does. For example, a recent study by Dr. Harbrichter from Wisconsin noted there were patients initially thought to have type 3, who were discovered to have but had severe forms of type 1C. In the end treatment will be based on bleeding symptoms, so at times the difference is academic. However, it is important as those with certain types of mutations in type 3 are much more susceptible to inhibitor development.