Thalassemia free survival after allogeneic stem cell transplantation (SCT) is about 80–90% with either matched related or unrelated donors. However, the probability of finding a HLA-compatible donor is less than 50%. We explored the use of a mismatched related (“Haplo-”) donor. All patients received two courses of pre-transplant immunosuppression therapy (PTIS) with fludarabine (Flu) and dexamethasone (Dxm) to facilitate engraftment. After two courses of PTIS, a reduced-toxicity conditioning regimen of rabbit anti-thymocyte globulin (ATG), Flu, and IV Busulfan (Bu) was given followed by T-cell replete peripheral blood progenitor cells (PBPC). GVHD prophylaxis consisted of cyclophosphamide (Cy) on days SCT +3 and +4 (Post-Cy), and on day SCT +5 tacrolimus or sirolimus was started together with a short course of mycophenolate mofetil. Thirty-one patients underwent haplo-SCT. Their median age was ten years (range, 2 to 20 years). Twenty-nine patients engrafted with 100% donor chimerism. Two of three patients with high titers of donor-specific anti-HLA antibodies suffered primary graft failure. Median time to neutrophil engraftment was 14 days (range, 11 to 18 days). Five patients developed mild to moderate, reversible veno-occlusive disease, while nine patients developed acute GVHD grade II, that quickly responded to steroid therapy. Only five patients developed limited chronic GVHD. Projected overall and event-free survival rates at two years are 95% and 94%, respectively. The median follow up time is 12 months (range; 7 to 33 months). This haplo-SCT protocol may yield excellent outcomes for thalassemia patients, and provide a treatment option for patients lacking a HLA-matched donor.

Improving outcomes among class 3 thalassemia patients receiving allogeneic hematopoietic stem cell transplantations (HSCT) remains a challenge. Before HSCT, patients who were ≥ 7 years old and had a liver size ≥ 5 cm constitute what the Center for International Blood and Marrow Transplant Research defined as a very high–risk subset of a conventional high-risk class 3 group (here referred to as class 3 HR). We performed HSCT in 98 patients with related and unrelated donor stem cells. Seventy-six of the patients with age < 10 years received the more conventional myeloablative conditioning (MAC) regimen (cyclophosphamide, busulfan, ± fludarabine); the remaining 22 patients with age ≥ 10 years and hepatomegaly (class 3 HR), and in several instances additional comorbidity problems, underwent HSCT with a novel reduced-toxicity conditioning (RTC) regimen (fludarabine and busulfan). We then compared the outcomes between these 2 groups (MAC versus RTC). Event-free survival (86% versus 90%) and overall survival (95% versus 90%) were not significantly different between the respective groups; however, there was a higher incidence of serious treatment-related complications in the MAC group, and although we experienced 6 graft failures in the MAC group (8%), there were none in the RTC group. Based on these results, we suggest that (1) class 3 HR thalassemia patients can safely receive HSCT with our novel RTC regimen and achieve the same excellent outcome as low/standard-risk thalassemia patients who received the standard MAC regimen, and further, (2) that this novel RTC approach should be tested in the low/standard-risk patient population.

We defined the molecular basis and correlated the hematological phenotypes with the globin genotypes in 52 patients with Hb H disease and 29 patients with AEBart’s disease of northeast Thailand. Among the former group, the most prevalent molecular defect was found to be the interaction of α-thalassemia 1 (SEA type) with the Hb Constant Spring (Hb CS; 35 of 52 patients), followed by the deletion of three α-globin genes with the SEA type α-thalassemia 1 and the 3.7- or 4.2-kb deletion of α-thalassemia 2 (14 of 52 patients) and the interaction of the SEA α-thalassemia 1 with the Hb Paksé which was found in the remaining 3 patients. Among the 29 patients of the latter group, in 18 disease was caused by interactions of Hb E heterozygotes with the SEA α-thalassemia 1 and Hb CS. Interaction of Hb E heterozygotes with a deletional form of Hb H disease was detected in 7 patients and the Hb Paksé AEBart’s disease was found in another 3 patients. A remaining patient with an unusually severe form of AEBart’s disease with a lower Hb E level and observable Hb H was associated with a hitherto undescribed condition, the interaction of Hb E heterozygote with α-thalassemia 1 and an α2 codon 30 (GAG) deletion. Hematological characterization of the patients demonstrated that although disease in most of them was associated with thalassemia intermedia phenotypes, it was apparent that association with the nondeletional form of α-thalassemia 2 produced a more severe phenotype than that of the deletional one. Therefore, α-globin gene analysis of Hb H and AEBart’s disease patients would be useful for predicting the clinical outcome and improving genetic counseling.

beta-Thalassemia mutations in 71 chromosomes of Thai patients from the northeast, the middle and the south of the country were investigated using dot blot hybridization of PCR (polymerase chain reaction)-amplified DNA with allele-specific oligonucleotide probes. Eight different known molecular defects were detected, at different frequencies. There was an amber mutation in codon 17, a C-T transversion at position 654 of IVS-2, a frameshift mutation between codons 71 and 72, an A-G transition at nucleotide -28 within the TATA box (known as Chinese mutations), a G-T transversion at position 1 of IVS-1 (an Indian mutation), a 4 bp deletion in codons 41/42 and a G-C transversion at position 5 of IVS-1 (described as both Chinese and Indian mutations) and a Thai original mutation, an ochre mutation in codon 35. Analysis of the three unknown alleles by DNA sequencing of the cloned DNA fragment amplified by PCR revealed an A-G substitution at the second position of the codon for amino acid 19 (AAC-AGC). The analytic approach used in the present study and the characteristic distribution of mutations in each region of Thailand will prove useful for setting up a prenatal diagnosis program.

We describe the hematological and DNA characterization of hemoglobin (Hb) E heterozygote with various forms of alpha-thalassemia in Thai individuals. Altogether, 202 unrelated adult subjects with Hb E heterozygotes either with or without alpha-thalassemia determinant were studied. The most prevalent interaction was found to be a double heterozygote for Hb E/alpha-thalassemia 2, followed by a double Hb E/alpha-thalassemia 1 and a Hb E/Hb Constant Spring (CS), even though the Hb CS was not detected. Double heterozygotes for Hb E and homozygous alpha-thalassemia 2 and Hb E with a compound alpha-thalassemia 2/Hb CS were also encountered with lower frequencies. Unexpectedly, as many as 18 cases previously diagnosed as Hb E carriers at routine Hb analysis were indeed Hb E heterozygotes with compound alpha-thalassemia 1/alpha-thalassemia 2, indicating a need for globin genotyping for accurate diagnosis. A change in Hb E level was observed which was related to a concomitant inheritance of alpha-thalassemia. The hematological expression of these Hb E heterozygotes with various forms of alpha-thalassemia, including a hitherto undescribed condition of double heterozygosity for Hb E/Hb Paksé identified in two subjects, is presented comparatively with those of the 80 cases of pure Hb E carriers. A multiplex allele-specific polymerase chain reaction (PCR) assay for simultaneous detection of Hb E and Hb CS genes is also described.