The Philadelphia chromosome (Ph) derives from the balanced translocation between chromosomes 9 and 22. This chromosomal translocation results in the fusion between the 5' part of the BCR gene, normally located on chromosome 22, and the 3' part of the ABL gene on chromosome 9 giving origin to a BCR-ABL fusion gene which is transcribed and then translated into a hybrid protein. In general, three breakpoint cluster regions in the BCR gene have been described: major (M-BCR), minor (m-BCR) and micro (μ-BCR). Three main variants of the BCR-ABL gene have been described depending on the length of the sequence of the BCR gene included that encode for the P190, P210, P230 proteins. Most patients (95 %) were found to have P210 protein that resulted from rearrangement in the M-BCR region in the BCR gene and thus gives rise to b2a2 or b3a2 variants. The incidence of one or other rearrangement in chronic myeloid leukemia (CML) patients varies in different reported series. These two variants are associated with distinct clinical types of human leukemias. In this study, we report the frequencies of M-BCR-ABL fusion transcripts in 44 CML patients and we review the data on the correlations between the type of M-BCR/ABL variant and the corresponding sex, age and biological features. Forty-four untreated chronic phase CML patients were studied. The type of BCR-ABL fusion transcripts was determined by reverse transcriptase polymerase chain reaction (RT-PCR). More than half of them showed b3a2 fusion transcript (64 %), while (36 %) showed b2a2 transcript. No patients coexpressed b3a2/b2a2. Correlation between biological data demonstrated that: (a) M-BCR rearrangements were not associated with the sex of the patients. (b) Patients with b3a2 rearrangements were older than patients with b2a2 transcripts. (c) M-BCR rearrangements were influenced neither by the white blood count (WBC) nor with hemoglobin levels. However, platelet level is more elevated in patients with b3a2 transcript (681.2/L vs. 207/L; P = 0.001). In conclusion, we observed significant correlations between age, platelet level and M-BCR-ABL transcript, these observations deserve further investigations.

BackgroundInfectious etiology in lymphoproliferative diseases has always been suspected. The pathogenic roles of human herpesvirus-6 (HHV-6) in acute leukemia have been of great interest. Discordant results to establish a link between HHV-6 activation and the genesis of acute leukemia have been observed. The objective of this study was to evaluate a possible association between HHV-6 infection and acute leukemia in children and adults, with a longitudinal follow-up at diagnosis, aplasia, remission and relapse.MethodsHHV-6 load was quantified by a quantitative real-time PCR in the blood and bone marrow samples from 37 children and 36 adults with acute leukemia: 33 B acute lymphoblastic leukemia (B-ALL), 6 T acute lymphoblastic leukemia (T-ALL), 34 acute myeloid leukemia (AML).ResultsHHV-6 was detected in 15%, 8%, 30% and 28% of the blood samples at diagnosis, aplasia, remission and relapse, respectively. The median viral loads were 138, 244, 112 and 78 copies/million cells at diagnosis, aplasia, remission and relapse, respectively. In the bone marrow samples, HHV-6 was detected in 5%, 20% and 23% of the samples at diagnosis, remission and relapse, respectively. The median viral loads were 34, 109 and 32 copies/million cells at diagnosis, remission and relapse, respectively. According to the type of leukemia at diagnosis, HHV-6 was detected in 19% of the blood samples and in 7% of the bone marrow samples (with median viral loads at 206 and 79 copies/million cells, respectively) from patients with B-ALL. For patients with AML, HHV-6 was present in 8% of the blood samples and in 4% of the bone marrow samples (with median viral loads at 68 and 12 copies/million cells, respectively). HHV-6 was more prevalent in the blood samples from children than from adults (25% and 9%, respectively) and for the bone marrow (11% and 0%, respectively). All typable HHV-6 were HHV-6B species. No link was shown between neither the clinical symptoms nor the abnormal karyotype and HHV-6 activation. A case of HHV-6 chromosomal integration was shown in one patient with AML.ConclusionThis study confirms the absence of role of HHV-6 in the genesis of acute leukemia but the virus was reactivated after chemotherapy treatment.

Dasatinib is a second-line tyrosine kinase inhibitor used in patients with imatinib resistant or intolerant chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute leukemia. Gastrointestinal bleeding may occur in up to 7% of patients using dasatinib, although, severe dasatinib-related acute colitis had rarely been reported. Here, we present the case of a 36-year-old female who progressed to acute myeloid leukemia after fourteen months of receiving imatinib for CML in the chronic phase and was treated with a dasatinib-containing chemotherapy regimen. On day 34 of treatment, the patient developed moderate abdominal pain and bloody diarrhea with mucous. Analyses of stool specimens were negative for parasites, Clostridium difficile, and other pathogenic bacteria. The cytomegalovirus pp65 antigen was negative in her blood leukocytes. A colonoscopy revealed acute colitis, and a mucosal biopsy showed nonspecific colitis. The patient was treated with broad-spectrum antibiotics, bowel rest and hydration, and dasatinib treatment was stopped. Her bloody diarrhea improved within 72 h. After confirming cytological remission, the patient received initial course of consolidation, and dasatinib treatment was reinstated. However, hemorrhagic colitis recurred. After discontinuing dasatinib, herhemorrhagic colitis drastically improved and did not recur following the administration of nilotinib. The characteristics of our patient suggest that dasatinib treatment can lead to hemorrhagic colitis, which typically resolves after discontinuation of the drug.

Acute promyelocytic leukemia (APL) is genetically characterized by a reciprocal translocation between chromosomes 15 and 17, t(15;17)(q22;q21), which results in the fusion gene PML-RARA. A small proportion of patients with APL have complex or simple variants of this translocation. With conventional cytogenetic methods, these translocations are detected in about 70-90 % of patients, with most of the negative results due to technical problems or cryptic variants. Those masked PML/RARA fusions can be identified by molecular analyses such as reverse transcriptase-polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH). We report the case of a 58-year-old man showing morphological, cytochemical, and immunophenotypic features of hypergranular APL (FAB-M4). PML-RARA transcripts were not evident on RT-PCR. Although cytogenetic tests revealed the presence of an apparently balanced translocation t(15;17)(q24;q11) with an abnormal chromosome 12 that characterized a M3 leukemia. This karyotypic interpretation was confirmed by FISH with the use of painting probes of chromosomes 12, 15, and 17 and a PML-RARA dual-color DNA probe. FISH showed a PML-RARA fusion gene on the der(12) instead of the der(15). The patient was treated with an all-trans retinoic acid (ATRA) plus anthracycline-based protocol and achieved complete remission, with no recurrence to date. These results illustrate the usefulness of combining cytogenetics and FISH methods to evidence the PML/RARA fusion gene in cases with morphologic suspicion of APL with variant or cryptic t(15;17).

Perforin gene (PRF1) mutations have been identified in some patients diagnosed with the familial form of hemophagocytic lymphohistiocytosis (HLH) and in patients with lymphoma. The aim of the present study was to determine whether patients with a familial aggregation of hematological malignancies harbor germline perforin gene mutations. For this purpose, 81 unrelated families from Tunisia and France with aggregated hematological malignancies were investigated. The variants detected in the PRF1 coding region amounted to 3.7% (3/81). Two of the three variants identified were previously described: the p.Ala91Val pathogenic mutation and the p.Asn252Ser polymorphism. A new p.Ala 211Val missense substitution was identified in two related Tunisian patients. In order to assess the pathogenicity of this new variation, bioinformatic tools were used to predict its effects on the perforin protein structure and at the mRNA level. The segregation of the mutant allele was studied in the family of interest and a control population was screened. The fact that this variant was not found to occur in 200 control chromosomes suggests that it may be pathogenic. However, overexpression of mutated PRF1 in rat basophilic leukemia cells did not affect the lytic function of perforin differently from the wild type protein.