Successful Unrelated Bone Marrow Transplantation for Three patients with Amegakaryocytic Thrombocytopenia with Radio-Ulnar Synostosis (CTRUS) in Japan

Abstract

Abstract 4510 Objectives: Amegakaryocytic thrombocytopenia with radio-ulnar synostosis (CTRUS) is a rare inherited bone marrow failure syndrome that has the potential to progress to pancytopenia that behaves like TAR.The diagnosis of CTRUS is made later when pronation-supination of the forearm is discovered to be restricted. Hox 11a was reported to be abnormal in the initial cases but at least 1 other case did not have this abnormality. Hematopoietic stem-cell transplantation (HSCT) is presently the only curative treatment approach. We used a reduced intensity transplantation regimen in CTRUS patient with aplastic anemia.We reported two cases of CTRUS who underwent successful unrelated bone marrow transplantation. Methods: Conditioning regimen consisted of Flu, ATG, CY, and TLI (300cGy). For GVHD prophylaxis, all received FK506 and short course MTX. The number of transplanted nucleated cells were 6.35, 6.8, 5.8 ×108/kg. All patients underwent an alternative donor SCT. The each age at transplant for patients were 8, 18,11 months. Results: The patients had rapid and durable engraftment at day +13, +16, +23 with minimal complications.No regimen related toxicity were observed, and no viral re-activation (CMV, EBV, VZV) were seen. Each patients developed acute GVHD involving skin only (grade I - II).One of three patients developed chronic GVHD (skin only limited type). All patients are alive and transfusion independent with each follow-up time of 61, 56, 33 months. Conclusions: Allo-BMT from an unrelated donor is a curative and suitable approach for patients with amegakaryocytic thrombocytopenia with radio-ulnar synostosis (CTRUS), reduced intensity conditioning might be a feasible approach to stem-cell transplantation in patients who do not have a sibling donor. In our three cases, the mutation in exon 2 of HOXA11 gene was not found, which may suggest that these cases are possibly a subtype of this syndrome.Careful clinical course watching is required if another complications or the disease relapse will occur again. Disclosures: No relevant conflicts of interest to declare.