A Study in Type 1 Gaucher Patients to Evaluate the Pharmacokinetics, Safety and Pharmacodynamics of AT2101

Inclusion Criteria: * Have a confirmed diagnosis of type 1 Gaucher disease with a documented gene mutation; * Clinically stable and on a stable dose of ERT for at least 2 years before study entry, with no changes to dose level or regimen in the last 6 months; * Willing to stop ERT for the duration of the study; * Male or female between the ages of 18 to 65 inclusive; * All subjects of reproductive potential are required to practice an acceptable method of contraception; * All subjects must have a body mass index of less than 30; and * Provide written informed consent to participate in the study. Exclusion Criteria: * A clinically significant disease, severe complications from Gaucher disease, or serious intercurrent illness that may preclude participation in the study in the opinion of the Investigator; * During the screening/wash out period, any clinically significant findings, based on physical exam, medical history review, lab assessment, vital sign assessment and/or other significant finding which would compromise the safety of the subject, or preclude the subject from completing the study as deemed by the Investigator; * Partial or total splenectomy; * History of pulmonary hypertension or Gaucher-related lung disease; * History of allergy or sensitivity to the study drug or any excipients, including any prior serious allergic reaction to iminosugars; * Screening or Day 1 (before dosing) 12-lead ECG demonstration QTc \>450 msec in males or \>470 in females; * Pregnant or breast-feeding; * Current/recent drug or alcohol abuse within the past 12 months; * Treatment with any investigational product, including investigational forms of ERT, in the 90 days before study entry; * Treatment in the previous 90 days with any drug known to have a well-defined potential for toxicity to a major organ; * Presence or sequelae of gastrointestinal, liver or kidney disease, or other conditions known to interfere with the absorption, distribution, metabolism, or excretion of drugs; or * Subject is otherwise unsuitable for the study in the opinion of the Investigator.