A 5-year-old child presented with abdominal distension, pallor, easy bruising and bone pain. On physical examination, hepatosplenomegaly and lymphadenopathy was noted. Child was suspected to have metabolic disorder. So, biopsy and histopathologic examination was planned from bone marrow. On staining and microscopic examination, a distended phagocytic cell was noted. It had fibrillary type of cytoplasm with eccentrically placed nucleus. PAS staining was intensively positive. The x-ray of right lower limb is given below Which of the following is the main management strategy in the above condition?