<qa>  What is the primary goal of this study?The primary goal of this study is to evaluate an alternative myeloablative, but reduced toxicity conditioning regimen in children, to describe the safety and efficacy of intravenous i.v. Treosulfan administered as part of a standardised Fludarabine-containing conditioning and to contribute to the current pharmacokinetic model to be able to finally give age or body surface area dependent dose recommendations. The treatment regimens given in the protocol MC-FludT.17M are based on sufficient clinical safety and efficacy data. Considering the vital indication for allogeneic haematopoietic stem cell transplantation of the selected patient population, the risk-benefit assessment is therefore reasonably in favour of the study conduct. 