Plasma samples will be obtained every 3 months to measure disease markers and safety profiles. Proteasome samples will be taken at screening and month 6 to identify proteins that may be associated with Gaucher disease. Blood will be obtained at month 1 from the first 6 consenting patients who have been randomly assigned to take OGT 918. These patients will also have a cerebrospinal fluid sample taken by lumbar puncture at month 1. These samples will be measured for how much OGT 918 is present.