The β-haemoglobinopathies are the most prevalent inherited disorders worldwide. Gene therapy of β-thalassaemia is particularly challenging given the requirement for massive haemoglobin production in a lineage-specific manner and the lack of selective advantage for corrected haematopoietic stem cells. Compound βE/β0-thalassaemia is the most common form of severe thalassaemia in southeast Asian countries and their diasporas1,2. The βE-globin allele bears a point mutation that causes alternative splicing. The abnormally spliced form is non-coding, whereas the correctly spliced messenger RNA expresses a mutated βE-globin with partial instability1,2. When this is compounded with a non-functional β0 allele, a profound decrease in β-globin synthesis results, and approximately half of βE/β0-thalassaemia patients are transfusion-dependent1,2. The only available curative therapy is allogeneic haematopoietic stem cell transplantation, although most patients do not have a human-leukocyte-antigen-matched, geno-identical donor, and those who do still risk rejection or graft-versus-host disease. Here we show that, 33 months after lentiviral β-globin gene transfer, an adult patient with severe βE/β0-thalassaemia dependent on monthly transfusions since early childhood has become trans-fusion independent for the past 21 months. Blood haemoglobin is maintained between 9 and 10 g dl–1, of which one-third contains vector-encoded β-globin. Most of the therapeutic benefit results from a dominant, myeloid-biased cell clone, in which the integrated vector causes transcriptional activation of HMGA2 in erythroid cells with further increased expression of a truncated HMGA2 mRNA insensitive to degradation by let-7 microRNAs. The clonal dominance that accompanies therapeutic efficacy may be coincidental and stochasticor resultfrom a hithertobenign cellexpansion caused by dysregulation of the HMGA2 gene in stem/progenitor cells.

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Cord blood from an unrelated donor is an alternative source of hematopoietic stem cells for adults with acute leukemia who lack an HLA-matched bone marrow donor.

Umbilical cord blood is an alternative hematopoietic stem cell source for patients with hematologic diseases who can be cured by allogeneic hematopoietic cell transplantation. Initially, umbilical cord blood transplantation was limited to children, given the low cell dose infused. Both related and unrelated cord blood transplants have been performed with high rates of success for a variety of hematologic disorders and metabolic storage diseases in the pediatric setting. The results for adult umbilical cord blood transplantation have improved, with greater emphasis on cord blood units of sufficient cell dose and human leukocyte antigen match and with the use of double umbilical cord blood units and improved supportive care techniques. Cord blood expansion trials have recently shown improvement in time to engraftment. Umbilical cord blood is being compared with other graft sources in both retrospective and prospective trials. The growth of the field over the last 25 years and the plans for future exploration are discussed.

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SUMMARY Background Umbilical cord blood (UCB) is increasingly considered as an alternative to peripheral blood progenitor cells (PBPC) or bone marrow (BM), especially when a HLA-matched adult unrelated donor is not available. Methods In order to establish the appropriateness of current graft selection practices, we retrospectively compared leukemia-free survival and other outcomes for each graft source in patients aged >16 years transplanted for acute leukemia using Cox regression. Data were available on 1525 patients transplanted between 2002 and 2006 using UCB (n=165), PBPC (n=888) and BM (n=472). UCB units were matched at HLA-A and B at antigen level and DRB1 at allele level (n=10) or mismatched at one (n=40) or two antigens (n=115). PBPC and BM grafts from unrelated adult donors were matched for allele-level HLA-A, B, C and DRB1 (n=632; n=332) or mismatched at one locus (n=256; n=140). Findings Leukemia-free survival after UCB transplantation was comparable to that observed after 8/8 and 7/8 allele-matched PBPC or BM transplantation. Transplant-related mortality, however, was higher after UCB transplantation compared to 8/8 allele-matched PBPC (HR 1.62, p<0.01) or BM (HR 1.69, p<0.01). Grades 2–4 acute and chronic graft-versus-host disease were lower in UCB recipients compared to allele-matched PBPC (HR 0.57, p<0.01 and HR 0.38, p<0.01, respectively), while chronic and not acute graft-versus-host disease was lower after UCB compared to allele-matched BM transplantation (HR 0.63, p=0.01). Interpretation Together, these data support the use of UCB for adults with acute leukemia when an HLA-matched unrelated adult donor is lacking and when transplant is urgently needed.

The Fanconi anemia and BRCA networks are considered interconnected, as BRCA2 gene defects have been discovered in individuals with Fanconi anemia subtype D1. Here we show that a defect in the BRCA2-interacting protein PALB2 is associated with Fanconi anemia in an individual with a new subtype. PALB2-deficient cells showed hypersensitivity to cross-linking agents and lacked chromatin-bound BRCA2; these defects were corrected upon ectopic expression of PALB2 or by spontaneous reversion.

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