Characterization of additional genetic events in childhood acute lymphoblastic leukemia with TEL/AML1 gene fusion: a molecular cytogenetics study

TEL/AML1 gene fusion that results from a cryptic t(12;21) is the most common genetic aberration in childhood B-lineage acute lymphoblastic leukemia (ALL). While the translocation may initiate the leukemic process, critical secondary genetic events are currently believed to be pivotal for leukemogenesis. We investigated 12 cases of childhood ALL with TEL/AML1 gene fusion by fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH) and documented additional or secondary genetic changes in seven patients (58%). Three patients showed extra copies of chromosome 21 including a case in which the trisomy 21 (+21) clone was distinct from the one harboring TEL/AML1 gene fusion. Interestingly, one patient without +21 showed amplification of the AML1 gene on chromosome 21q, supporting the contention that AML1 amplification may be an important additional genetic event. Gene expression study by semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR) in two of these four patients showed an increase in AML1 transcripts that paralleled the increase in gene copy number. Deletion of the normal TEL allele was detected in two patients, with one of them showing loss of chromosome 12 together with duplication of the der(12)t(12;21). Finally, one patient showed duplication of the fusion signal. Our findings confirm that additional or secondary genetic changes including AML1 amplification are commonly encountered in childhood ALL with TEL/AML1 gene fusion, which are envisaged to play significant roles in disease progression.

Clinical phenotype of triplicated alpha-globin genes and heterozygosity for beta0-thalassemia in Chinese subjects

The presence of extra copies of alpha-globin gene has been shown to worsen the degree of anemia in beta-thalassemia heterozygotes. We describe the clinical phenotype of eight Chinese subjects with heterozygosity for both triplicated alpha-globin gene and a beta0-thalassemia allele. They were identified through genotyping of beta-thalassemia intermedia and major patients, and through community-based thalassemia screening program in Hong Kong. Standard molecular techniques were used in the determination of genotype. All subjects in this series showed five copies of alpha-globin genes (alphaalphaalpha/alphaalpha) in association with a beta0-thalassemia allele. Although genotypically identical, six subjects showed a beta-thalassemia intermedia phenotype while two were clinically indistinguishable from beta-thalassemia minor, implying the presence of genetic modifying factors that remained undefined. Triplication of alpha-globin gene and heterozygosity for beta0-thalassemia accounted for 15% of beta-thalassemia intermedia patients at our locality and was associated with a mild clinical phenotype. This genotype was not found among beta-thalassemia major patients. They presented in adulthood and were usually not transfusion dependent. When compared with simple beta-thalassemia heterozygotes, they showed obvious red cell abnormalities (hypochromasia, anisopoikilocytosis, circulating normoblasts), lower hemoglobin (Hb) and higher HbF levels. The presence of triplicated alpha-globin genes should always be considered in apparent beta-thalassemia carriers who were more symptomatic than expected, so that unnecessary investigations for the cause of anemia could be avoided. Finally, triplication of alpha-globin genes should be looked for in families with children affected by beta-thalassemia intermedia in which only one parent showed a picture of beta-thalassemia on Hb analysis.

Late onset post-transplantation lymphoproliferative disease of recipient origin following cytogenetic relapse and occult autologous haematopoietic regeneration after allogeneic bone marrow transplantation for acute myeloid leukaemia

A post-transplantation lymphoproliferative disease (PTLD) of recipient origin was identified in one of 376 consecutive cases of allogeneic bone marrow transplantation (BMT). This occurred in a 36-year-old woman who received an allogeneic BMT for acute myeloid leukaemia in relapse. At 15 months after BMT, recipient haematopietic and leukaemic cells were found in the bone marrow, which disappeared on withdrawal of immunosuppression. However, severe graft-versus-host disease (GVHD) necessitated the continuation of immunosuppression, leading to the occurrence of PTLD in the liver and lung 12 months afterwards. Fluorescence in situ hybridisation showed that the neoplastic cells were of recipient origin. Although the PTLD also responded completely to withdrawal of immunosuppression, the patient finally died from the complications of GVHD. This case of late onset PTLD post-BMT showed features similar to those in solid organ transplantation, in that the tumour was of recipient origin and responded well to the withdrawal of immunosuppression. Of further interest is that recipient lymphoid regeneration had accompanied autologous haematopoietic regeneration and become a target for subsequent neoplastic transformation.

Disseminated hepatosplenic mycobacterial infection masking myeloproliferative diseases as leukemoid reaction: a diagnostic pitfall

The distinction of myeloproliferative disease (MPD) from leukemoid reactions due to reactive causes can be difficult. In the presence of simultaneous occurrence of MPD and an established infection, only the demonstration of a clonal marker or prolonged observation can substantiate the diagnosis. We present three cases of MPD presenting as leukemoid reaction due to disseminated hepatosplenic mycobacterial sepsis. There appeared to be an association between MPD and reduced resistance to mycobacterial infection. Clinicians and hematologist should be aware of such a predisposition and possible dual pathology for proper diagnosis, therapy and monitoring of both the infection and the myeloproliferation.

Philadelphia (Ph) chromosome-positive chronic myeloid leukaemia relapsing as Ph-negative leukaemia after allogeneic bone marrow transplantation

Two patients with Philadelphia chromosome-positive (Ph(+)) chronic myeloid leukaemia (CML) relapsed 1.5 and 5 years after allogeneic bone marrow transplantation (BMT). Although the leukaemias were of recipient origin, t(9;22) could no longer be detected using conventional cytogenetics/fluorescence in situ hybridization or molecularly. Both patients responded to immunotherapy with donor lymphocytes/peripheral blood stem cells, although one patient ultimately relapsed again. These patients were similar to the occurrence of Ph(-) leukaemias previously described in Ph(+) CML after treatment with interferon or autologous BMT, and might be relevant in the pathogenesis and monitoring of treatment after BMT in CML.

Derivative (1;18)(q10;q10): a recurrent and novel unbalanced translocation involving 1q in myeloid disorders

We report two cases of hematological malignancies, comprising a case of myelodysplastic syndrome (MDS) that rapidly evolved into acute myeloid leukemia, and a case of myeloproliferative disorder (MPD), in which der(1;18)(q10;q10) was found as the sole acquired karyotypic abnormality. This observation indicates that the unbalanced translocation is a recurrent aberration in myeloid disorders. To the best of our knowledge, centromeric fusion between long arms of chromosomes 1 and 18, leading to a normal chromosome 18 substituted with a der(1;18) chromosome, is novel and has not been described in cancer. Mechanistically, either trisomy 1q or monosomy 18p that results from the translocation may potentially contribute to leukemogenesis. Finally, chromosomes with large constitutive heterochromatin bands such as chromosome 1 may be at risk of centromeric instability and be predisposed to centromeric fusion with other chromosomes.

The predictive parameters of erythropoietin hyporesponsiveness in patients on continuous ambulatory peritoneal dialysis

BACKGROUND

The present study was aimed at investigating the predictive parameters of erythropoietin (epoetin) hyporesponsiveness in patients on continuous ambulatory peritoneal dialysis (CAPD).

METHODS

We studied 40 patients with end-stage renal disease who had been receiving CAPD for at least 6 months and epoetin therapy for at least more than 2 months. Pearson's simple correlation and multiple stepwise linear regression analysis was used to discover what parameter can predict epoetin resistance. We expressed epoetin resistance index (ERI) as weekly epoetin dose/hematocrit/body weight'. The dose of epoetin is titrated by about 25% every 2 to 4 weeks to maintain a target hematocrit level between 33% and 36%.

RESULTS

We analyzed the relationship between ERI and other predictive parameters by Pearson's correlation. These results showed ERI has a statistically significant correlation with transferrin saturation (TS) (r = -0.327, p = 0.042), total weekly Kt/Vurea (r = -0.423, p = 0.018), serum albumin level (r = -0.458, p = 0.003), normalized protein catabolic rate (nPCR) (r = -0.479, p = 0.006), normalized protein equivalent of total nitrogen appearance (nPNA) (r = -0.488, p = 0.005) and serum C-reactive protein (CRP) (r = 0.332, p = 0.036). Regression analysis was performed using stepwise linear regression for multiple variables to discover the most independent variable which is correlated with ERI. ERI was entered as a dependent variable, whereas the other parameters (age, duration of peritoneal dialysis, serum albumin level, CRP, serum ferritin, total weekly Kt/Vurea, nPCR, nPNA, serum iPTH, serum aluminium, TS) were entered as independent variables. This analysis showed CRP is the most significant variable and, if CRP is excluded, nPNA is the significant variable. CRP has a statistically significant correlation with serum albumin level (r = -0.418, p = 0.007) and total weekly Kt/Vurea (r = -0.366, p = 0.043). High CRP group has more increased level of ERI (p < 0.05), age (p < 0.05) and serum creatinine level (p < 0.05) than normal control, but more decreased level of serum albumin (p < 0.01) and serum iron levels (p < 0.05).

CONCLUSION

These results indicate that CRP is the most important predictor of epoetin hyporesponsiveness.

Should we screen for globin gene mutations in blood samples with mean corpuscular volume (MCV) greater than 80 fL in areas with a high prevalence of thalassaemia?

AIMS

To investigate whether it is worthwhile, in areas where thalassaemia is common, to screen for globin gene mutations in subjects with a mean corpuscular volume (MCV) above 80 fL, especially in partners of known thalassaemia carriers.

METHODS

Blood samples from 95 subjects with MCV between 80 and 85 fL were screened for the presence of alpha globin gene mutations and the haemoglobin (Hb) E mutation.

RESULTS

Thirty four subjects harboured globin gene mutations. Of these, 31 had deletions of one alpha globin gene, one had Hb Constant Spring, and three had Hb E mutations.

CONCLUSION

Based on the above figures and known prevalence rates of thalassaemia carriers, it would seem worthwhile to screen for globin gene mutations in partners of known thalassaemia carriers, regardless of MCV, to identify pregnancies at risk of Hb H disease or Hb E/beta thalassaemia.

Primary CD56 positive lymphomas of the gastrointestinal tract

BACKGROUND

Primary CD56 positive lymphoma of the gastrointestinal (GI) tract is rare. Genotypically, these tumors can be classified into natural killer (NK)-like T-cell lymphoma or NK cell lymphoma by the presence or absence of T-cell receptor (TCR) gene rearrangement. However, they have a considerable degree of morphologic and immunophenotypic overlap, making a definitive diagnosis difficult.

METHODS

The clinicopathologic features of three patients with primary CD56 positive lymphoma of the small and large bowel are presented. This is followed by a review of the English literature from 1966 to the present.

RESULTS

All patients had CD56 positive/CD3epsilon positive disease on paraffin section. Two patients were positive for Epstein-Barr virus-encoded early nuclear RNAs (EBER) according to in situ histochemistry results and were negative for TCR gene rearrangement, consistent with primary NK lymphoma of the GI tract. The other patient was EBER negative with rearranged TCR, consistent with NK-like T-cell lymphoma. There was no clinical or histologic evidence of enteropathy in any of the patients. The major presenting symptoms included fever, weight loss, and intestinal perforation. All patients died between 1 week and 6 months after diagnosis despite undergoing surgery and intensive chemotherapy.

CONCLUSIONS

These results, together with a literature review, suggest that primary NK cell lymphoma of the GI tract may be considered a distinct clinicopathologic entity. Both primary NK and NK-like T-cell lymphoma pursue an aggressive clinical course. EBER and TCR gene rearrangement are useful in distinguishing NK cell lymphoma from NK-like T-cell lymphoma, particularly when frozen tissue is not available for immunophenotyping.

Haemoglobin Q-Thailand and hereditary spherocytosis in a Chinese family

A Chinese family with concurrent hereditary spherocytosis (HS) and haemoglobin (Hb) Q-Thailand is described. The Hb Q-Thailand mutation was found on the remaining alpha1 globin gene on a chromosome 16 containing the (-alpha 4.2) deletion. Active haemolysis in members of this family is segregated with the HS phenotype, and the Hb Q-Thailand in the heterozygous state does not seem to show any modulating effect on HS.

Therapy-related myelodysplastic syndrome of recipient origin after allogeneic bone marrow transplantation for acute lymphoblastic leukaemia

Therapy-related myelodysplastic syndrome (t-MDS) is a very rare complication of allogeneic bone marrow transplantation (BMT). A woman with T acute lymphoblastic leukaemia (T-ALL) received an allogeneic BMT from a donor with the beta-thalassaemic trait. Five years after BMT, the red cell indices returned to normal after an initial conversion to microcytosis, implying autologous haematopoietic regeneration. Seven years after BMT, thrombocytopenia developed and marrow examination confirmed t-MDS, with a characteristic karyotype 46,XX,inv(3)(q21;q26), del(5)(q13),add(17)(p11). Retrospective molecular analysis of donor/recipient chimaerism showed gradual regeneration of recipient cells after BMT, culminating at the time of t-MDS. Our findings illustrate the unusual occurrence of t-MDS after allogeneic BMT. Re-emergence of recipient haematopoesis may herald the development of a haematological malignancy different from the original neoplastic clone for which the BMT was performed.

Nodal plasmacytoma with significant paraproteinaemia

We present a case of primary nodal plasmacytoma in an elderly Chinese woman that was associated with significant paraproteinaemia and paraproteinuria. Clinical and laboratory features of the patient satisfied Durie's criteria for the diagnosis of multiple myeloma. The present case was unusual in two aspects. Firstly, there was no evidence of clonal plasma cell proliferation elsewhere in the body after extensive radiological investigations, repeated bone marrow examinations, and polymerase chain reaction for immunoglobulin gene rearrangement study. Secondly, the clinical behaviour was indolent despite the large amount of paraprotein production, and showed satisfactory disease control with local radiotherapy. The differential diagnoses of plasmacytosis in the lymph node are also discussed.

Hairy cell leukemia in Hong Kong Chinese: a 12-year retrospective survey

BACKGROUND

Hairy cell leukemia (HCL) is a unique chronic B cell lymphoproliferative disease (B-LPD), with distinct clinical and pathological features, and excellent treatment response to 2-chlorodeoxyadenosine (2-CDA) and pentostatin. There have been few reports of HCL from oriental countries.

PATIENTS AND METHODS

A retrospective survey of HCL in six major hematology units in Hong Kong over a 12-year period.

RESULTS

There were 18 cases of HCL identified. Most patients presented with fever, splenomegaly and monocytopenia. Lymphadenopathy was present in three patients, and open biopsy revealed tuberculosis infection in two cases. Seven cases received interferon and 12 cases received 2-CDA. Four patients died from bronchogenic carcinoma, cerebral vascular accident, fulminant hepatitis B virus reactivation and malignant melanoma. The remaining 14 patients are in clinical remission at a median of 6 years' follow-up; two are also surviving from second malignancies (thyroid papillary carcinoma and renal cell carcinoma).

CONCLUSIONS

Parallel to the low incidence of B-LPD in Chinese, the incidence of HCL (0.035/100000 population per year) is much lower than in Western series. Other clinical features such as male dominance, clinical presentation, response to 2-CDA treatment, and association with second malignancy are similar to Western reports. However, two common complications in the Chinese population are the fulminant reactivation of hepatitis B infection and disseminated tuberculosis infection.

Acute myeloid leukaemia with giant granules: association with t(10; 11)(p13; q14) and disseminated intravascular coagulation

A 16-year-old Chinese girl presented with AML-M5a. A bone marrow examination showed that the myeloblasts which were overwhelming the marrow contained giant granules (pseudo-Chediak-Higashi anomaly). Her karyotype showed a rare translocation t(10; 11)(p13; q14). Molecular delineation of the translocation breakpoints was not possible. Nonetheless, this case further demonstrates the morphological and phenotypic heterogeneity of acute leukaemia with this translocation. In this girl it was associated with disseminated intravascular coagulation.

Effects of antioxidants and a caspase inhibitor on chloramphenicol-induced toxicity of human bone marrow and HL-60 cells

Chloramphenicol (CAP), a board spectrum antibiotic widely used in many developing countries, has toxic side effects on bone marrow, the most serious of which is aplastic anemia. Recent studies suggest that effects of CAP on suppressing hematopoietic colony formation may be abrogated by antioxidants. In addition, there is preliminary evidence that CAP induces apoptosis in hemopoietic stem cells, leading to aplastic anemia. We have been unable to demonstrate the protective effects of a variety of antioxidants on CAP-induced suppression of burst-forming unit erythroid (BFU-E) and colony-forming unit granulocyte/monocyte (CFU-GM). Using flow cytometry, we have, however, confirmed that CAP can induce apoptosis in purified human bone marrow CD34+ cells. We also showed that a caspase inhibitor, Z-VAD.fmk, can ameliorate the apoptotic-inducing effects of CAP in the HL-60 cell line.