Clinical response to GD1 therapy. (A-C) Laboratory response after initiation of Gaucher disease therapy in patient 1 (blue) and patient 2 (red) as assessed by chitotriosidase (A), LGL-1 (B), and serum M-spike (C). (D) Hematologic improvement after initiation of GD1 therapy. (E) Bone marrow biopsies pretreatment (2019) and posttreatment (2020, 2021); hematoxylin and eosin stain (upper panels) and CD138 immunohistochemical stain highlighting plasma cells (lower panels). Arrows indicate aggregates of atypical macrophages with fibrillar cytoplasm typical of “Gaucher cells.” Scale bar represents 50 μm. A marked reduction in plasma cells is seen after GD1 treatment. Chitotriosidase is measured in nmol/hr/mL. Hgb, hemoglobin; LGL1, plasma lysoglucosylceremide, (ng/mL); M-spike, monoclonal spike (g/dL); Plt, platelet; WBC, white blood cell count.