Allogeneic Hematopoietic Stem Cell Transplant for Patients With Inborn Errors of Immunity

0.8 mg/kg IV infusion over 2 hours

40 mg/m2 IV infusion over 30 min once daily for 4 days

"AUC Targeted Dose based on busulfan test dose PKs, IV infusion over 3 hours once daily (3.2 mg/kg IV per day will be the default dose) per the below time frame: For 10/10 Matched Related and Unrelated Donor Recipients For the High Intensity Arm, the busulfan dose will be given for 4 days (-6, -5, -4, and -3).~For Intermediate Intensity Arm, the busulfan dose will be given for 3 days (-6,-5, and -4).~For Low Intensity Arm, the busulfan dose will be given for 2 days on days (-6 and -5). 9/10 HLA Matched Related or Unrelated Donor Recipients For the High Intensity Arm, the busulfan dose will be given for 3 days (-6,~-5, and -4). For the the Intermediate Intensity Arm, the busulfan dose will be given for 2 days (-6 and -5).~For the Low Intensity Arm, the busulfan dose will be given for 1 day on day (-6)."

Alemtuzumab will be given if there is evidence of immune dysregulation 10 mg/m2 SC divided over three days (-14, -13, and -12)

200 cGy Transplant Day -1 (Only for 9/10 HLA Matched Related or Unrelated Donor Recipients )

Stem cell transplant

Tacrolimus 0.02 mg/kg IV continuous infusion over 24 hours starting on day +5

Mycophenolate mofetil 15 mg/kg IV over 2 hours three times a day starting on day +5 will continue until Approximately+35 (+/- two days)

Cyclophosphamide: 50 mg/kg IV once daily over 2 hours on days +3 and +4, dosed according to ideal body weight