Inclusion Criteria:

• Signed informed consent.
• Confirmed diagnosis of Type I Gaucher disease, with no prior enzyme replacement therapy, gene therapy or bone marrow transplantation, and who are ambulatory.
• Age 10-65 (patients 66-70 years of age are considered on a case-by-case basis following careful medical review).
• Dual energy X-ray absorptiometry (DEXA) of the femoral nech with a T-score ≤ -1.0.
• One of more of the following signs as documented by X-ray, computed tomography (CT), or magnetic resonance imaging (MRI), or symptoms of bone disease as documented in the patient’s medical history or baseline examinations: a). history of at least one bone crises; b). Erlenmeyer flask deformity of the femora in children (10-17 years old); c). osteoarticular necrosis; d). medullary infarctions; e). lytic lesions; f). pathological fractures or fractures related to Gaucher disease; g). marrow infiltration to a degree such that Rosenthal’s Magnetic Resonance Score was ≥ 3; h). bone density by quantitative computed tomography (QCT) or DEXA ≥ 1.5 standard deviation (SD) below age-adjusted normal value; and i). fat fraction ≤ 17%.

Exclusion Criteria:

• More than 1 joint replacement (revision surgery such as repair or replacement of a previously replaced joint is allowed).
• Pregnant, lactating or per-menopausal women.
• Active, uncontrolled infection, such as hepatitis B, hepatitis C or human immunodeficiency virus (HIV).
• Major concurrent disorders (i.e. cancer, renal disease) or disorders known to affect bone (e.g. uncontrolled thyroid disease, hyperparathyroidism, hypoparathyroidism, gastrectomy, malabsorption, inflammatory bowel disease, rheumatoid arthritis, ankylosing spondylitis).
• Medications known to affect bone homeostasis (e.g. chronic oral corticosteroids, anticonvulsants, phenytoin and phenobarbital, hyper-physiological doses of estrogen, defined as > 0.625mg, or androgens, bisphosphates, calcitonin) within the first 2 months of the first Cerezyme infusion.
• Emotional, behavioral or psychological problems, which in the judgment of the principal investigator, would interfere with the patient adequately complying with the requirement of the study.