A Case Report of HLA 5/10 Cord Blood Cell Engraftment in a Patient with Severe β Thalassemia after Haplo-Cord Stem Cell Transplantation.

β-Thalassemia major (β-TM) is an autosomal recessive genetic disorder characterized by a deficiency in the synthesis of β-globin chains, leading to reduced functional hemoglobin and life-threatening chronic anemia. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative treatment for β-TM, with outcomes dependent on stable donor engraftment, donor-derived erythropoiesis, and low transplant-related complications. Herein, we report a case of a 27-month-old male patient with β-TM who achieved successful, sustained engraftment using unrelated umbilical cord blood (UCB) following haplo-cord stem cell transplantation. The patient received a combination of 7/12 HLA-matched haploidentical peripheral blood stem cells (haplo-PBSCs) and 5/10 HLA-matched unrelated UCB. Post-transplant monitoring confirmed exclusive engraftment of UCB (full chimerism via short tandem repeat polymerase chain reaction [STR-PCR]) with complete hematopoietic reconstitution. As of the last follow-up, the patient has maintained disease-free survival for over 36 months without significant chronic graft-versus-host disease (GVHD) and with stable hemoglobin levels (90-130 g/L). This case provides evidence that HLA 5/10 mismatched unrelated UCB can achieve effective engraftment in β-TM patients undergoing haplo-cord transplantation, supporting its potential as an alternative donor source for patients lacking fully matched donors.