For example, plasma MPA levels are not routinely monitored in clinical practice and are subject to many additional parameters, such as: (i) the percentage of patients receiving 45 mg/kg/day, administered t.i.d. up to a maximum of 3 g, which is the recommended dose and schedule for GVHD prophylaxis [29–31]; (ii) the route and duration of administration; and (iii) the serum albumin concentration, which correlates with MPA clearance because MPA is highly bound to serum albumin [27]. This evidence concerns the gene ALB and graft versus host disease.