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Enhanced fetal hemoglobin (Hb F) production can partially compensate for the lack of adult hemoglobin (Hb A) in patients with beta-thalassemia major or intermedia, and ameliorate the clinical severity of these diseases. To further elucidate factors governing Hb F levels, we evaluated demographic, clinical, laboratory, and genetic characteristics in 241 unrelated adult beta-thalassemia carriers in Hong Kong. They had wide variations in Hb F and F-cell numbers skewing toward higher levels. Individuals who coinherited the Xmn IT-allele in the (G)gamma-globin gene promoter had higher Hb F and more F-cells compared with those lacking the Xmn I T-allele. However, both groups exhibited a similarly wide spread of Hb F and F-cells. The correlation of Hb F and F-cells corresponded well to both linear and exponential models, suggesting multiple mechanisms for Hb F augmentation. The heritabilities of Hb F and F-cells were calculated in 66 families (111 parents who were beta-thalassemia carriers and 82 asymptomatic offspring) to be 0.7 to 0.9. The Xmn I polymorphism accounted for 9% of the Hb F and 13% of the F-cell heritabilities. These results suggest that these family members are well suited for genome wide association studies that will identify genetic loci regulating Hb F production, and likely novel pharmacological targets for reactivating Hb F production in adults., (Copyright 2008 Wiley-Liss, Inc.)

Thrombotic microangiopathy (TMA) is a grave complication after haematopoietic stem cell transplantation (HSCT) and effective treatment is undefined. Five patients with postHSCT TMA, which was refractory to at least 1 week of plasma exchange and prednisolone, were treated with rituximab (375 mg/m(2)/week x 4). Remission was achieved in four patients, of whom three remained in remission and one had died of sepsis at a median follow-up of 10 months. ADAMTS13 levels were low in all evaluable patients, and only one patient showed significant anti-ADAMTS13 antibody. The levels of ADAMTS13 and anti-ADAMTS13 antibody did not change significantly with rituximab-induced remission.

In this report we examine the (AC)n(AT)xTy motif residing -530 bp 5' upstream of the beta-globin gene in Chinese thalassaemic patients. This motif is a putative binding site for a repressor protein, termed beta protein 1 (BP1) (Berg et al., Nucleic Acids Res 1989;17:8833-8852). Variations in the (AC)n(AT)xTy repeats affect the binding affinity of BP1, thereby altering the expression of the beta-globin gene. Eight different configurations of this repeat motif are identified in our population of Chinese beta-thalassaemia patients. A (AC)3(AT)7T5 motif was identified among these thalassaemia patients and its influence in beta-globin gene expression was studied using stable transfection assay in murine erythroleukemia (MEL) cells. Our data demonstrated that the (AC)3(AT)7T5 motif has a moderately strong repressor effect on the expression of the cis-linked beta-globin gene. The high affinity of BP1 for this motif may result in the suppression of the transcription of the beta-globin gene (Berg et al., Am J Hematol 1991;36:42-47). We postulate that silencer elements in the beta-globin promoter play an important role in modifying the clinical presentation of the disease., ((c) 2006 Wiley-Liss, Inc.)

Anti-Lepore haemoglobins (Hb) are rare betadelta fusion variants that arise from non-homologous crossover during meiosis, resulting in a delta-betadelta-beta configuration. A novel anti-Lepore mutation (anti-Lepore Hong Kong) was found in two Chinese families with raised Hb A(2). Direct sequencing revealed a crossover within a 54-bp region spanning the junction of cap site (CAP) and exon 1, which predicted the production of normal delta-globin. Determination of alpha/beta-mRNA ratios by quantitative real-time polymerase chain reaction demonstrated downregulation of the beta gene in cis due to the interposed betadelta fusion gene. Although heterozygotes have normal red cell indices and are clinically silent, compound heterozygotes with beta(0) mutation in trans produce a mild thalassaemia intermedia phenotype with a markedly raised Hb A(2) level that may mimic clinically mild Hb E-beta(+)-thalassaemia. Awareness of the presence of anti-Lepore Hong Kong will help to resolve diagnostic problems in regions with significant prevalence of globin disorders.

Ten patients developing lymphomas after disease modifying anti-rheumatic drugs (DMARD) (methotrexate, n = 3, mean cumulative dose = 3.4 g; cyclophosphamide, n = 2, mean dose = 70 g; azathioprine, n = 6, mean dose = 243 g) were investigated. Methotrexate-related lymphomas were Epstein-Barr virus (EBV)-positive, had infrequent aberrant methylation of p15 and p16, and responded well to methotrexate withdrawal or anti-CD20 antibody (rituximab) alone without concomitant chemotherapy, implying that defective immunosurveillance was important in lymphomagenesis. However, 75% of cyclophosphamide/azathioprine-related lymphomas were EBV-negative, had frequent p15 and p16 methylation, and responded poorly to drug withdrawal and chemotherapy, implying that direct drug-induced mutagenesis might be involved in lymphomagenesis., ((c) 2005 Wiley-Liss, Inc.)

Ninety consecutive patients with acute promyelocytic leukaemia were investigated for promoter methylation of CDKN2B (alias p15) and CDKN2A (alias p16) in disease relapse and progression. CDKN2B methylation was significantly more frequent at first relapse (30/36, 83%) than at presentation (48/77, 62%) (P=0.025), while CDKN2A methylation appeared unaffected. Both acquisition and loss of CDKN2B methylation happened at relapse, with acquisition more frequent. No significant increase in CDKN2B and CDKN2A methylation occurred at more advanced relapses. At first or subsequent relapses, owing to highly effective salvage by arsenic trioxide, CDKN2B methylation did not impact on event-free survival or overall survival.

A 70-year-old man with B-cell chronic lymphocytic leukemia (CLL) received single-agent treatment with the purine analogue fludarabine, which led to complete remission. After 8 years, he presented with pancytopenia. Marrow examination showed acute myeloid leukemia (AML) with trilineage myelodysplasia (MDS). Cytogenetic analysis showed an unbalanced der(1;7)(p10;q10) that resulted effectively in deletion 7q; confirming the diagnosis of therapy-related AML (t-AML). No residual CLL was present. Together with previous reports of secondary cancers after fludarabine treatment and the association of monosomy 7/7q- with another purine analogue azathioprine, results suggest that t-AML might develop after fludarabine therapy., (Copyright (c) 2005 Wiley-Liss, Inc.)

FLT-3 aberrations that occur as an internal tandem duplication (ITD) or a mutation at the activation-loop position 835, D835, are common in acute promyelocytic leukaemia (APL). We investigated the clinicopathological associations and prognostic impact of FLT-3 aberrations in a cohort of APL patients. FLT-3 exons 11 and 12 were amplified by polymerase chain reaction (PCR), and the ITD was recognized as an increase in the size of the PCR product. FLT-3 exon 17 was amplified, and D835 mutation was identified by loss of an EcoRV site, followed by DNA sequencing. Of 82 patients studied, FLT-3 aberrations were detected in 35 cases (43%) at diagnosis (ITD: 16; D835 mutation: 18; ITD + D835 mutation: 1). FLT-3 ITD, but not D835 mutations, was significantly associated with higher presentation white blood cell count (WBC) and microgranular morphology. Early/induction deaths were related to male sex and high presentation WBC. There was a trend for FLT-3 ITD to be associated with non-remission (P = 0.06). For disease-free survival, high WBC was the only significant adverse factor. Male sex, high WBC and FLT-3 ITD were significant adverse factors for overall survival. These findings have important implications on the possible use of FLT-3 inhibitors in the treatment of APL.