The purpose of this study is to conduct a pilot trial of a Precision Dosing approach to
alemtuzumab dosing for allogeneic hematopoietic cell transplantation of patients with
non-malignant diseases. The investigators will measure the ability to use a population PK
model of alemtuzumab to target patient Day 0 alemtuzumab levels to 0.15-0.6ug/mL in a pilot
study of 20 patients.