Adult patients with Gaucher Disease Type 1 who have previously received SRT (substrate replacement therapy) and are now receiving ERT (enzyme replacement therapy) with velaglucerase alfa. For group B, no visits are required since this is a retrospective data collection. For group A, there are visits every 3 months for 1 year. These will include drawing blood, using an app on your cell phone to answer questionnaires, and an interview at the end of the study.