Immune reconstitution following first definitive cellular therapy. Dark horizontal line represents median. Thick vertical bars represent interquartile range. Thin vertical bars represent range. Red horizontal line represents the 10th percentile of lymphocyte subsets in healthy 1- to 2-year-old children.⁵⁷ ERT-GT (Lv), enzyme replacement therapy followed by lentivirus gene therapy; ERT-GT (Rv), enzyme replacement therapy followed by retroviral gene therapy; FDCT, first definitive cellular therapy; Ig, immunoglobulin.