Background: Haematopoietic stem cell transplantation (HSCT) represents the definitive treatment for many non-malignant diseases. Treosulfan is considered a safe and effective conditioning drug compared to other conventional myeloablative conditioning (MAC) regimens, especially in patients with comorbidities. Aim of the work: To evaluate the safety and efficacy of Fludarabine-Treosulfan-Thiotepa reduced toxicity conditioning in different paediatric nonmalignant disease. Patients and methods: 54 patients (55 transplants) were reviewed retrospectively, they had metabolic, immunodeficiency, BM failure, hemoglobinopathy and other nonmalignant diseases. All had the same conditioning. 96% received serotherapy (Alemtuzumab/ATG).  post-transplant Graft-versus-Host disease (GVHD) prophylaxis was given in all patients, based mostly on ciclosporin. 90% of the patients were fully HLA-matched. Results: Median age at transplant was six years. No primary graft failure, 4%(n=2) had secondary graft failure. Overall survival at a median follow-up of 15months was 90.9%. Neutrophil engraftment occurred at a median of 12 days, Platelet engraftment occurred at a median of 19 days. immune reconstitution was achieved at a median time of nine Chimerism was full donor in 64%(n=35), high donor in 18%(n=10), and mixed donor in 6%(n=3). 60%(n=33) developed GVHD but only 4%(n=2) had acute severe GVHD, another 4%(n=2) had severe chronic GVHD. One patient had severe VOD.
Conclusion: This study demonstrates that Fludarabine-Treosulfan-Thiotepa regimen is a safe and effective conditioning that can achieve engraftment, with very low rates of graft failure, transplant-related mortality and morbidity, even if it is used twice in the same patient.