Long-term assessment of iduronidase activity in patients with MPS-IH after HCT. (A-C) Leukocyte IDUA activity in UCB and BM recipients. Black dots represent individuals with myeloid chimerism <85%, and the actual myeloid chimerism percentages are shown in parentheses. Note, of the 4 UCB patients with <85% myeloid chimerism, 2 were 6/6 HLA-matched, and 2 were 5/6 HLA-matched. (D-F) Plasma IDUA activity in UCB and BM recipients. Black dots represent individuals with myeloid chimerism <85%. Shown are the means and standard deviation; P values are derived from a Student’s t test. (G,H) IDUA levels over time from HCT with P values from linear regression analyses for each cohort.