The presence of a chromosomal abnormality in cytopenia without dysplasia identifies a category of high-risk clonal cytopenia of unknown significance

Myelodysplastic syndromes (MDS) are hematological malignancies classically defined by the presence of cytopenia(s) and dysmorphic myeloid cells. It is now known that MDS can be preceded by a pre-malignant condition called clonal cytopenia of unknown significance (CCUS), which associates a clonality marker with cytopenia in the absence of criteria of dysplasia. However, to date, it is not clear whether chromosomal abnormalities should be considered in the definition of CCUS or if they carry a prognostic impact in CCUS patients. In this study, we analyzed the clinico-biological features and outcomes of 34 patients who presented with one or more cytopenias, an absence of significant dysplasia, and a presence of a chromosomal abnormality (CA). We named this entity chromosomal abnormality with cytopenia of undetermined significance (CACtUS). We show that these patients are slightly older than MDS patients and that they more frequently presented with normocytic anemia. Most CACtUS patients exhibited only one unbalanced CA. The number and type of mutations were comparable between CACtUS patients and MDS patients. Regardless of the cytogenetic abnormality, the clinicobiological characteristics, overall survival, and risk of progression to high-risk (HR) MDS were similar between CACtUS patients and low-risk MDS patients. Thus, we suggest that CACtUS patients can be considered as HR-CCUS and should receive the follow-up regimen recommended for MDS patients.

The CADM1 tumor suppressor gene is a major candidate gene in MDS with deletion of the long arm of chromosome 11

Myelodysplastic syndromes (MDS) represent a heterogeneous group of clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis leading to peripheral cytopenias and in a substantial proportion of cases to acute myeloid leukemia. The deletion of the long arm of chromosome 11, del(11q), is a rare but recurrent clonal event in MDS. Here, we detail the largest series of 113 cases of MDS and myelodysplastic syndromes/myeloproliferative neoplasms (MDS/MPN) harboring a del(11q) analyzed at clinical, cytological, cytogenetic, and molecular levels. Female predominance, a survival prognosis similar to other MDS, a low monocyte count, and dysmegakaryopoiesis were the specific clinical and cytological features of del(11q) MDS. In most cases, del(11q) was isolated, primary and interstitial encompassing the 11q22-23 region containing ATM, KMT2A, and CBL genes. The common deleted region at 11q23.2 is centered on an intergenic region between CADM1 (also known as Tumor Suppressor in Lung Cancer 1) and NXPE2. CADM1 was expressed in all myeloid cells analyzed in contrast to NXPE2. At the functional level, the deletion of Cadm1 in murine Lineage-Sca1+Kit+ cells modifies the lymphoid-to-myeloid ratio in bone marrow, although not altering their multilineage hematopoietic reconstitution potential after syngenic transplantation. Together with the frequent simultaneous deletions of KMT2A, ATM, and CBL and mutations of ASXL1, SF3B1, and CBL, we show that CADM1 may be important in the physiopathology of the del(11q) MDS, extending its role as tumor-suppressor gene from solid tumors to hematopoietic malignancies.

Clinical and biological features of B-cell neoplasms with CDK6 translocations: an association with a subgroup of splenic marginal zone lymphomas displaying frequent CD5 expression, prolymphocytic cells, and TP53 abnormalities

A translocation involving the cyclin-dependent kinase 6 (CDK6) gene [t(CDK6)] is a rare but recurrent abnormality in B-cell neoplasms. To further characterise this aberration, we studied 57 cases; the largest series reported to date. Fluorescence in situ hybridisation analysis confirmed the involvement of CDK6 in all cases, including t(2;7)(p11;q21) immunoglobulin kappa locus (IGK)/CDK6 (n = 51), t(7;14)(q21;q32) CDK6/immunoglobulin heavy locus (IGH) (n = 2) and the previously undescribed t(7;14)(q21;q11) CDK6/T-cell receptor alpha locus (TRA)/T-cell receptor delta locus (TRD) (n = 4). In total, 10 patients were diagnosed with chronic lymphocytic leukaemia, monoclonal B-cell lymphocytosis or small lymphocytic lymphoma, and 47 had small B-cell lymphoma (SmBL) including 36 cases of marginal zone lymphoma (MZL; 34 splenic MZLs, one nodal MZL and one bronchus-associated lymphoid tissue lymphoma). In all, 18 of the 26 cytologically reviewed cases of MZL (69%) had an atypical aspect with prolymphocytic cells. Among the 47 patients with MZL/SmBL, CD5 expression was found in 26 (55%) and the tumour protein p53 (TP53) deletion in 22 (47%). The TP53 gene was mutated in 10/30 (33%); the 7q deletion was detected in only one case, and no Notch receptor 2 (NOTCH2) mutations were found. Immunoglobulin heavy-chain variable-region (IGHV) locus sequencing revealed that none harboured an IGHV1-02*04 gene. Overall survival was 82% at 10 years and not influenced by TP53 aberration. Our present findings suggest that most t(CDK6)+ neoplasms correspond to a particular subgroup of indolent marginal zone B-cell lymphomas with distinctive features.

NUP98 is rearranged in 3.8% of pediatric AML forming a clinical and molecular homogenous group with a poor prognosis

Pediatric acute myeloid leukemia (AML) is a rare disease whose prognosis is highly variable according to factors such as chromosomal abnormalities. Recurrent genomic rearrangements are detected in half of pediatric AML by karyotype. NUcleoPorin 98 (NUP98) gene is rearranged with 31 different fusion partner genes. These rearrangements are frequently undetected by conventional cytogenetics, as the NUP98 gene is located at the end of the chromosome 11 short arm (11p15). By screening a series of 574 pediatric AML, we detected a NUP98 rearrangement in 22 cases (3.8%), a frequency similar to CBFB-MYH11 fusion gene (4.0%). The most frequent NUP98 fusion gene partner is NSD1. These cases are homogeneous regarding their biological and clinical characteristics, and associated with bad prognosis only improved by bone marrow transplantation. We detailed the biological characteristics of these AML by exome sequencing which demonstrated few recurrent mutations (FLT3 ITD, WT1, CEBPA, NBPF14, BCR and ODF1). The analysis of the clonal structure in these cases suggests that the mutation order in the NUP98-rearranged pediatric AML begins with the NUP98 rearrangement leading to epigenetic dysregulations then followed by mutations of critical hematopoietic transcription factors and finally, activation of the FLT3 signaling pathway.

An early thymic precursor phenotype predicts outcome exclusively in HOXA-overexpressing adult T-cell acute lymphoblastic leukemia: a Group for Research in Adult Acute Lymphoblastic Leukemia study

Gene expression studies have consistently identified a HOXA-overexpressing cluster of T-cell acute lymphoblastic leukemias, but it is unclear whether these constitute a homogeneous clinical entity, and the biological consequences of HOXA overexpression have not been systematically examined. We characterized the biology and outcome of 55 HOXA-positive cases among 209 patients with adult T-cell acute lymphoblastic leukemia uniformly treated during the Group for Research on Adult Acute Lymphoblastic Leukemia (GRAALL)-2003 and -2005 studies. HOXA-positive patients had markedly higher rates of an early thymic precursor-like immunophenotype (40.8% versus 14.5%, P=0.0004), chemoresistance (59.3% versus 40.8%, P=0.026) and positivity for minimal residual disease (48.5% versus 23.5%, P=0.01) than the HOXA-negative group. These differences were due to particularly high frequencies of chemoresistant early thymic precursor-like acute lymphoblastic leukemia in HOXA-positive cases harboring fusion oncoproteins that transactivate HOXA Strikingly, the presence of an early thymic precursor-like immunophenotype was associated with marked outcome differences within the HOXA-positive group (5-year overall survival 31.2% in HOXA-positive early thymic precursor versus 66.7% in HOXA-positive non-early thymic precursor, P=0.03), but not in HOXA-negative cases (5-year overall survival 74.2% in HOXA-negative early thymic precursor versus 57.2% in HOXA-negative non-early thymic precursor, P=0.44). Multivariate analysis further revealed that HOXA positivity independently affected event-free survival (P=0.053) and relapse risk (P=0.039) of chemoresistant T-cell acute lymphoblastic leukemia. These results show that the underlying mechanism of HOXA deregulation dictates the clinico-biological phenotype, and that the negative prognosis of early thymic precursor acute lymphoblastic leukemia is exclusive to HOXA-positive patients, suggesting that early treatment intensification is currently suboptimal for therapeutic rescue of HOXA-positive chemoresistant adult early thymic precursor acute lymphoblastic leukemia.

TRIAL REGISTRATION

The GRAALL-2003 and -2005 studies were registered at http://www.clinicaltrials.gov as #NCT00222027 and #NCT00327678, respectively.

Small intestinal CD4+ T-cell lymphoma is a heterogenous entity with common pathology features

BACKGROUND & AIMS

Little is known about intestinal CD4+ T-cell lymphoma; this rare malignancy is misdiagnosed frequently. We evaluated diagnostic criteria and factors that might affect its development and outcome.

METHODS

In a retrospective analysis, we analyzed medical records and intestinal specimens from 10 patients diagnosed with intestinal CD4+ T-cell lymphoma among 115 consecutive patients examined for severe enteropathy with villous atrophy. Samples were analyzed by histology, flow cytometry, and comparative genomic hybridization.

RESULTS

Small-intestine epithelial and lamina propria tissues from patients who presented with chronic diarrhea and malnutrition had variable levels of infiltration of CD3+ CD4+ T cells. Flow cytometry showed a high frequency of CD4+ intraepithelial cells, which frequently expressed a specific Vβ chain. T-cell receptor β clonality was confirmed by DNA sequencing. Two patients had HLA and serology results compatible with celiac disease and autoimmune enteropathy, respectively. Two patients were found to have antibodies against human T-cell leukemia virus and 2 patients had signs of a recent infection with the herpes viruses. Comparative genomic hybridization analyses showed heterogeneous chromosomal abnormalities. Symptoms were reduced in patients treated with steroids (n = 5), but not in patients given purine analogues or chemotherapy. Antibodies against CD52 produced clinical and histologic responses in 2 of 2 patients, whereas severe adverse effects developed in 1 patient. At the latest follow-up evaluation, all patients were alive.

CONCLUSIONS

There is much heterogeneity in the onset and genetic features of intestinal CD4+ T-cell lymphomas, despite their common presentation as indolent lymphoproliferations of the intestinal mucosa. Patients should be treated with steroids, and possibly antibodies against CD52 (for the most aggressive forms of this disorder).

Large granular lymphocytic leukemia: a treatable form of refractory celiac disease

Large granular lymphocyte leukemia (LGL) is characterized by clonal expansion of CD3+ T cells or CD3(-) natural killer cells and frequently is associated with autoimmune diseases. We describe 2 patients with celiac disease who no longer responded to gluten-free diets after they developed T-cell LGL, with intestinal localization of malignant lymphocytes. Flow cytometry phenotyping of isolated intestinal intraepithelial and lamina propria cells eliminated type II refractory celiac disease, identifying large-sized CD8(+)CD57(+) T cells. Treatment with a combination of cyclosporine and methotrexate restored the patients' sensitivity to gluten-free diets. LGL therefore might be a cause of refractory celiac disease that is sensitive to immunosuppressive therapy.

Chronic lymphocytic leukemia and prolymphocytic leukemia with MYC translocations: a subgroup with an aggressive disease course

Translocations involving MYC are rare in chronic lymphocytic leukemia (CLL), and up to now, their prognostic significance remains unclear. We report the characteristics of 21 patients with CLL and nine patients with prolymphocytic leukemia (PLL), diagnosed in multiple centers (n = 13), which showed an MYC translocation demonstrated by fluorescence in situ hybridization. The prevalence was estimated to be <1%. Advanced age and male predominance were observed. Morphological analysis frequently revealed the presence of prolymphocytes. A typical "CLL-immunophenotype" was found in four of nine cases with PLL. Moreover, CD5 and CD23 were frequently expressed in PLL. The latter findings are atypical for PLL and may suggest transformation or progression of an underlying CLL. MYC translocations were frequently observed with concomitant adverse cytogenetic markers, such as del(11q) (n = 8/30) and/or del(17p)/monosomy 17 (n = 7/30). In addition, the presence of unbalanced translocations (n = 24 in 13/30 cases) and complex karyotype (n = 16/30) were frequent in cases with MYC translocations. Altogether, del(17p)/monosomy 17, del(11q), and/or complex karyotype were observed in 22 of 30 patients. Survival outcome was poor: the median time to treatment was only 5 months, and overall survival (OS) from clinical diagnosis and from genetic detection was 71 and 19 months, respectively. In conclusion, CLL/PLL with MYC translocations is a rare entity, which seems to be associated with adverse prognostic features and unfavorable outcome.

Functional analysis of the NUP98-CCDC28A fusion protein

BACKGROUND

The nucleoporin gene NUP98 is rearranged in more than 27 chromosomal abnormalities observed in childhood and adult, de novo and therapy-related acute leukemias of myeloid and T-lymphoid origins, resulting in the creation of fusion genes and the expression of chimeric proteins. We report here the functional analysis of the NUP98-coiled-coil domain-containing protein 28A (NUP98-CCDC28A) fusion protein, expressed as the consequence of a recurrent t(6;11)(q24.1;p15.5) translocation.

DESIGN AND METHODS

To gain insight into the function of the native CCDC28A gene, we collected information on any differential expression of CCDC28A among normal hematologic cell types and within subgroups of acute leukemia. To assess the in vivo effects of the NUP98-CCDC28A fusion, NUP98-CCDC28A or full length CCDC28A were retrovirally transduced into primary murine bone marrow cells and transduced cells were next transplanted into sub-lethally irradiated recipient mice.

RESULTS

Our in silico analyses supported a contribution of CCDC28A to discrete stages of murine hematopoietic development. They also suggested selective enrichment of CCDC28A in the French-American-British M6 class of human acute leukemia. Primary murine hematopoietic progenitor cells transduced with NUP98-CCDC28A generated a fully penetrant and transplantable myeloproliferative neoplasm-like myeloid leukemia and induced selective expansion of granulocyte/macrophage progenitors in the bone marrow of transplanted recipients, showing that NUP98-CCDC28A promotes the proliferative capacity and self-renewal potential of myeloid progenitors. In addition, the transformation mediated by NUP98-CCDC28A was not associated with deregulation of the Hoxa-Meis1 pathway, a feature shared by a diverse set of NUP98 fusions.

CONCLUSIONS

Our results demonstrate that the recurrent NUP98-CCDC28A is an oncogene that induces a rapid and transplantable myeloid neoplasm in recipient mice. They also provide additional evidence for an alternative leukemogenic mechanism for NUP98 oncogenes.

Epstein-Barr virus-induced gene 3 (EBI3): a novel diagnosis marker in Burkitt lymphoma and diffuse large B-cell lymphoma

The distinction between Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL), two types of mature aggressive B-cell lymphomas that require distinct treatments, can be difficult because of forms showing features intermediate between DLBCL and BL (here called BL/DLBCL). They can be discriminated by the presence of c-myc translocations characteristic of BL. However, these are not exclusive of BL and when present in DLBCL are associated with lower survival. In this study, we show that Epstein-Barr virus-induced gene 3 (EBI3) is differentially expressed among BL and DLBCL. Analysis of gene expression data from 502 cases of aggressive mature B-cell lymphomas available on Gene Expression Omnibus and immunohistochemical analysis of 184 cases of BL, BL/DLBCL or DLBCL, showed that EBI3 was not expressed in EBV-positive or -negative BL cases, whereas it was expressed by over 30% of tumoral cells in nearly 80% of DLBCL cases, independently of their subtypes. In addition, we show that c-myc overexpression represses EBI3 expression, and that DLBCL or BL/DLBCL cases with c-myc translocations have lower expression of EBI3. Thus, EBI3 immunohistochemistry could be useful to discriminate BL from DLBCL, and to identify cases of BL/DLBCL or DLBCL with potential c-myc translocations.

Specific chromosomal IG translocations have different prognoses in chronic lymphocytic leukemia

BACKGROUND

Chromosomal translocations are usually analyzed as a single entity, and are associated with a poor outcome in chronic lymphocytic leukemia. Translocations involving immunoglobulin genes are recurrent, but uncommon (<5%), and their individual prognosis is not clear. The two most frequent partners are BCL2 (18q21) and BCL3 (19q13).

DESIGNS AND METHODS

Herein, 75 cases are reported of chronic lymphocytic leukemia and t(14;18) (BCL2-CLLs). Our series benefits from morphological, immunological and cytogenetical reviews. The IGHV status analyses were performed by referring laboratories. Comparison was made with our previously published series of chronic lymphocytic leukemia patients with t(14;19) (BCL3-CLLs, n=29).

RESULTS

Compared with BCL3-CLLs, lymphocytosis was lower in BCL2-CLLs (p<0.008), and splenomegaly was less frequent (p<0.0001). There were more "typical" morphologies (p<0.005) and Matutes scores >4 (p<0.001) in the BCL2-CLLs group, and less CD38 expression (p<0.04). More variant BCL2-translocations were observed (t(18;22), n=11; 2t(2;18), n=2; p<0.02), and BCL2-translocation was frequently single (p<0.002). Complex karyotypes (p<0.02), trisomy 12 (p<0.03), 6q deletion (p<0.002) and TP53 deletion (p<0.02) were less frequent in BCL2-CLLs, whereas 13q deletion was more frequent (p<0.005). The IGHV gene was frequently mutated in BCL2-CLLs (p<0.0001). Treatment-free survival was longer in BCL2-CLLs (p<0.0001).

CONCLUSIONS

BCL2-CLL.S express CD5 and lack expression of CD38, and have a Matutes score ≥4, frequent trisomy 12, no ATM and 6q deletions, and a mutated IGHV status. Compared to BCL3-CLLs, BCL2-CLLs are much less aggressive; indicating that identifying individual translocations and cytogenetic partners would allow improved patient stratification.

Onset of autoimmune lymphoproliferative syndrome (ALPS) in humans as a consequence of genetic defect accumulation

Autoimmune diseases develop in approximately 5% of humans. They can arise when self-tolerance checkpoints of the immune system are bypassed as a consequence of inherited mutations of key genes involved in lymphocyte activation, survival, or death. For example, autoimmune lymphoproliferative syndrome (ALPS) results from defects in self-tolerance checkpoints as a consequence of mutations in the death receptor-encoding gene TNF receptor superfamily, member 6 (TNFRSF6; also known as FAS). However, some mutation carriers remain asymptomatic throughout life. We have now demonstrated in 7 ALPS patients that the disease develops as a consequence of an inherited TNFRSF6 heterozygous mutation combined with a somatic genetic event in the second TNFRSF6 allele. Analysis of the patients' CD4(-)CD8(-) (double negative) T cells--accumulation of which is a hallmark of ALPS--revealed that in these cells, 3 patients had somatic mutations in their second TNFRSF6 allele, while 4 patients had loss of heterozygosity by telomeric uniparental disomy of chromosome 10. This observation provides the molecular bases of a nonmalignant autoimmune disease development in humans and may shed light on the mechanism underlying the occurrence of other autoimmune diseases.

Targeting iron homeostasis induces cellular differentiation and synergizes with differentiating agents in acute myeloid leukemia

Differentiating agents have been proposed to overcome the impaired cellular differentiation in acute myeloid leukemia (AML). However, only the combinations of all-trans retinoic acid or arsenic trioxide with chemotherapy have been successful, and only in treating acute promyelocytic leukemia (also called AML3). We show that iron homeostasis is an effective target in the treatment of AML. Iron chelating therapy induces the differentiation of leukemia blasts and normal bone marrow precursors into monocytes/macrophages in a manner involving modulation of reactive oxygen species expression and the activation of mitogen-activated protein kinases (MAPKs). 30% of the genes most strongly induced by iron deprivation are also targeted by vitamin D3 (VD), a well known differentiating agent. Iron chelating agents induce expression and phosphorylation of the VD receptor (VDR), and iron deprivation and VD act synergistically. VD magnifies activation of MAPK JNK and the induction of VDR target genes. When used to treat one AML patient refractory to chemotherapy, the combination of iron-chelating agents and VD resulted in reversal of pancytopenia and in blast differentiation. We propose that iron availability modulates myeloid cell commitment and that targeting this cellular differentiation pathway together with conventional differentiating agents provides new therapeutic modalities for AML.

Deciphering leukemic B-cell chronic lymphoproliferative disorders

Diagnosis of leukemic B-cell chronic lymphoproliferative disorders (B-CLPD) is a frequent challenge in hematology. In this multicentric study, we prospectively studied 165 new consecutive leukemic patients with B-CLPD selected on the basis of Royal Marsden Hospital scoring system < or =3. The primary aim of the study was to try to decipher the atypical cases and identify homogenous subgroups. Overall, morphological examination contributed to diagnosis in only 20% cases, all of them CD5 negative. Thirty additional cases were CD5 negative suggestive of leukemic marginal zone lymphoma in most cases. The significantly poorer survival of the 26 cyclin D1 positive cases justifies recommending its systematic determination among atypical B-CLPD. CD20 expression segregated clearly two subgroups among CD5 positive cyclin D1 negative B-CLPD. The 17 patients with the CD20 dim profile represent a homogeneous subgroup very close to typical B-cell chronic lymphocytic leukemia (B-CLL) on morphological, phenotypical and cytogenetical criteria. In contrast, the subgroup of 51 patients with a CD20 bright profile is heterogeneous. Their significantly lower p27 expression level suggest the presence of a proliferative component, underlying a more aggressive disease. Further genomic studies are warranted to establish their precise nature. These cases should not be included in the same therapeutic trials as B-CLL.

Presentation and long-term follow-up of refractory celiac disease: comparison of type I with type II

BACKGROUND & AIMS

Refractory celiac disease (RCD) was recently subdivided into 2 subtypes (RCD I and II) based on a normal or abnormal phenotype of intraepithelial lymphocytes (IELs), respectively. It is not clear, however, if these 2 entities differ in their presentation at diagnosis or long-term outcome. We compared the clinical and biological characteristics of RCD I and RCD II at diagnosis, the risk of developing an overt lymphoma, and the predictive factors of survival.

METHODS

Medical files of 14 patients with RCD I and 43 with RCD II were analyzed retrospectively. Predictive factors of overt lymphoma and survival were studied in univariate and multivariate analyses.

RESULTS

At diagnosis, malnutrition, ulcerative jejunitis, and lymphocytic gastritis were more common in patients with RCD II than RCD I (P< .05). Overt lymphomas occurred in 2 patients with RCD I and 16 with RCD II. In the univariate analysis, abnormal IEL phenotype and increased age at diagnosis of RCD were predictive factors for overt lymphoma. Abnormal IEL phenotype (P< .01), clonality (P= .01), and overt lymphoma (P= .001) predicted short survival time. Only abnormal IEL phenotype (P= .03) and overt lymphoma (P= .04) were predictive in the multivariate analysis. The 5-year survival rate was 93% in patients with RCD I and 44% with RCD II.

CONCLUSIONS

RCD II has a much more severe presentation and prognosis than patients with RCD I; <44% of patients with RCD II survive 5 years after diagnosis. Abnormal IEL phenotype is a predictive factor but not a necessary condition for the development of overt lymphoma.

Long-term T-cell reconstitution after hematopoietic stem-cell transplantation in primary T-cell-immunodeficient patients is associated with myeloid chimerism and possibly the primary disease phenotype

We studied T-cell reconstitution in 31 primary T-cell-immunodeficient patients who had undergone hematopoietic stem-cell transplantation (HSCT) over 10 years previously. In 19 patients, there was no evidence of myeloid chimerism because little or no myeloablation had been performed. Given this context, we sought factors associated with good long-term T-cell reconstitution. We found that all patients having undergone full myeloablation had donor myeloid cells and persistent thymopoiesis, as evidenced by the presence of naive T cells carrying T-cell receptor excision circles (TRECs). In 9 patients with host myeloid chimerism, sustained thymic output was also observed and appeared to be associated with gammac deficiency. It is therefore possible that the complete absence of thymic progenitors characterizing this condition created a more favorable environment for thymic seeding by a population of early progenitor cells with the potential for self-renewal, thus enabling long-term (> 10 years) T-cell production.

Five members of the CEBP transcription factor family are targeted by recurrent IGH translocations in B-cell precursor acute lymphoblastic leukemia (BCP-ALL)

CCAAT enhancer-binding protein (CEBP) transcription factors play pivotal roles in proliferation and differentiation, including suppression of myeloid leukemogenesis. Mutations of CEBPA are found in a subset of acute myeloid leukemia (AML) and in some cases of familial AML. Here, using cytogenetics, fluorescence in situ hybridization (FISH), and molecular cloning, we show that 5 CEBP gene family members are targeted by recurrent IGH chromosomal translocations in BCP-ALL. Ten patients with t(8;14)(q11;q32) involved CEBPD on chromosome 8, and 9 patients with t(14;19)(q32;q13) involved CEBPA, while a further patient involved CEBPG, located 71 kb telomeric of CEBPA in chromosome band 19q13; 4 patients with inv(14)(q11q32)/t(14;14)(q11;q32) involved CEBPE and 3 patients with t(14;20)(q32;q13) involved CEBPB. In 16 patients the translocation breakpoints were cloned using long-distance inverse–polymerase chain reaction (LDI-PCR). With the exception of CEBPD breakpoints, which were scattered within a 43-kb region centromeric of CEBPD, translocation breakpoints were clustered immediately 5′ or 3′ of the involved CEBP gene. Except in 1 patient with t(14;14)(q11;q32), the involved CEBP genes retained germ-line sequences. Quantitative reverse transcription (RT)–PCR showed overexpression of the translocated CEBP gene. Our findings implicate the CEBP gene family as novel oncogenes in BCP-ALL, and suggest opposing functions of CEBP dysregulation in myeloid and lymphoid leukemogenesis.

Novel activating JAK2 mutation in a patient with Down syndrome and B-cell precursor acute lymphoblastic leukemia

Activation of tyrosine kinase genes is a frequent event in human hematologic malignancies. Because gene activation could be associated with gene dysregulation, we attempted to screen for activating gene mutation based on high-level gene expression. We focused our study on the Janus kinase 2 (JAK2) gene in 90 cases of acute leukemia. This strategy led to the identification of a novel JAK2-acquired mutation in a patient with Down syndrome (DS) with B-cell precursor acute lymphoblastic leukemia (BCP-ALL). This mutation involves a 5-amino acid deletion within the JH2 pseudokinase domain (JAK2DeltaIREED). Expression of JAK2DeltaIREED in Ba/F3 cells induced constitutive activation of the JAK-STAT pathway and growth factor-independent cell proliferation. These results highlight the JAK2 pseudokinase domain as an oncogenic hot spot and indicate that activation of the JAK-STAT pathway may contribute to lymphoid malignancies and hematologic disorders observed in children with DS.

NUP98 rearrangements in hematopoietic malignancies: a study of the Groupe Francophone de Cytogénétique Hématologique

The NUP98 gene is fused with 19 different partner genes in various human hematopoietic malignancies. In order to gain additional clinico-hematological data and to identify new partners of NUP98, the Groupe Francophone de Cytogénétique Hématologique (GFCH) collected cases of hematological malignancies where a 11p15 rearrangement was detected. Fluorescence in situ hybridization (FISH) analysis showed that 35% of these patients (23/66) carried a rearrangement of the NUP98 locus. Genes of the HOXA cluster and the nuclear-receptor set domain (NSD) genes were frequently fused to NUP98, mainly in de novo myeloid malignancies whereas the DDX10 and TOP1 genes were equally rearranged in de novo and in therapy-related myeloid proliferations. Involvement of ADD3 and C6ORF80 genes were detected, respectively, in myeloid disorders and in T-cell acute lymphoblastic leukemia (T-ALL), whereas the RAP1GDS1 gene was fused to NUP98 in T-ALL. Three new chromosomal breakpoints: 3q22.1, 7p15 (in a localization distinct from the HOXA locus) and Xq28 were detected in rearrangements with the NUP98 gene locus. The present study as well as a review of the 73 cases previously reported in the literature allowed us to delineate some chromosomal, clinical and molecular features of patients carrying a NUP98 gene rearrangements.

HOX11L2/TLX3 is transcriptionally activated through T-cell regulatory elements downstream of BCL11B as a result of the t(5;14)(q35;q32)

The t(5;14)(q35;q32) chromosomal translocation is specifically observed in up to 20% of childhood T-cell acute lymphoblastic leukemia (T-ALL). It affects the BCL11B/CTIP2 locus on chromosome 14 and the RANBP17-TLX3/HOX11L2 region on chromosome 5. It leads to ectopic activation of TLX3/HOX11L2. To investigate the reasons of the association between t(5;14) and T-ALL, we isolated the translocation breakpoints in 8 t(5;14) patients. Sequence analyses did not involve recombinase activity in the genesis of the translocation. We used DNAse1 hypersensitive experiments to locate transcriptional regulatory elements downstream of BCL11B. By transient transfection experiments, 2 of the 6 regions demonstrated cis-activation properties in T cells and were also effective on the TLX3 promoter. Our data indicate that the basis of the specific association between t(5;14) and T-ALL lies on the juxtaposition of TLX3 to long-range cis-activating regions active during T-cell differentiation.

Overexpression of CEBPA resulting from the translocation t(14;19)(q32;q13) of human precursor B acute lymphoblastic leukemia

Subtle variation in the expression or function of a small group of transcription factors can drive leukemogenesis. The CEBPA protein is known to regulate the balance between cell proliferation and differentiation during early hematopoietic development and myeloid differentiation. In human myeloid leukemia, CEBPA is frequently inactivated by mutation and indirect and posttranslational mechanisms, in keeping with tumor suppressor properties. We report that CEBPA is activated by juxtaposition to the immunoglobulin gene enhancer upon its rearrangement with the immunoglobulin heavy-chain locus in precursor B-cell acute lymphoblastic leukemia harboring t(14;19)(q32;q13). Overexpression of apparently normal CEBPA RNA or protein was observed in 6 patients. These data indicate that CEBPA may exhibit oncogenic as well as tumor suppressor properties in human leukemogenesis.

Acute megakaryoblastic leukemia and loss of the RUNX1 gene

Since the RUNX1 gene contributes to megakaryopoiesis and acquired trisomy 21 is the most frequent numerical chromosome anomaly in acute megakaryoblastic leukemia (AMLK), a systematic study of RUNX1 abnormalities was performed by fluorescence in situ hybridization in AMLK patients. Four abnormalities were detected among 15 patients. One copy of RUNX1 was completeley or partially lost in three patients and translocated onto Xq24 in the fourth. The possible consequences of RUNX1 haploinsufficiency are discussed.

Transient familial haemophagocytic lymphohistiocytosis reactivation post-CD34 haematopoietic stem cell transplantation

Familial haemophagocytic lymphohistiocytosis (FHLH) is a genetic disorder caused by defective lymphocyte cytotoxicity, resulting in impaired lymphocyte homeostasis and macrophage infiltration of solid tissues and bone marrow, with extensive haemophagocytosis. It is invariably fatal unless treated by allogeneic haematopoietic stem cell transplantation (HSCT). In a retrospective analysis of 11 cases of FHLH, transplanted in one centre between January 1999 and December 2003, it was found that host T cell expansion occurred early after HSCT in a setting of a viral infection (cytomegalovirus and Epstein-Barr virus respectively) in two cases who received T cell-depleted HSCT. Transient recurrence of clinical and biological manifestations of FHLH was observed, despite evidence for donor cell engraftment. Secondary development of donor T cells led to stable mixed chimaerism and sustained remission of FHLH. Detection of host-derived T cells soon after HSCT in a patient with FHLH should thus not mistakenly be taken as a manifestation of graft rejection.

Absence or Low Expression of Fas-Associated Protein with Death Domain in Acute Myeloid Leukemia Cells Predicts Resistance to Chemotherapy and Poor Outcome

In acute myeloid leukemia (AML), coexpression of death receptors and ligands of the tumor necrosis factor (TNF) receptor/TNF-alpha superfamily on leukemic cells after chemotherapy is not always accompanied by apoptosis, suggesting that the apoptotic death receptor signaling pathway is disrupted. Because Fas-associated protein with death domain (FADD) is the main adaptor for transmitting the Fas, TNF-related apoptosis-inducing ligand receptors, and TNF receptor 1 death signal, expression of FADD was analyzed by Western blot and immunocytochemistry in leukemic cells of 70 de novo AML patients treated with the European Organization of Research and Treatment of Cancer AML-10 randomized trial before initiation of induction chemotherapy. Thirty seven percent of patients (17 of 46) with FADD negative/low (FADD(-/low)) leukemic cells had a primary refractory disease compared with 12% of FADD(+) patients (3 of 24; P = 0.05). FADD(-/low) expression was significantly associated with a worse event-free survival [EFS (P = 0.04)] and overall survival (P = 0.04). In multivariate analysis, FADD(-/low) protein expression was independently associated with a poor EFS and overall survival (P = 0.002 and P = 0.026, respectively). Importantly, FADD(-/low) protein expression predicted poor EFS even in patients with standard- or good-risk AML (P = 0.009). Thus, we identified low or absent expression of the FADD protein in leukemic cells at diagnosis as a poor independent prognostic factor that can predict worse clinical outcome even for patients with standard- or good-risk AML.

Severe cutaneous papillomavirus disease after haemopoietic stem-cell transplantation in patients with severe combined immune deficiency caused by common gammac cytokine receptor subunit or JAK-3 deficiency

Haemopoietic stem-cell transplantation is a life-saving treatment for severe combined immune deficiency. However, there has been little long-term follow-up of this treatment. There is evidence for the persistance of partial immunodeficiency associated with significant infections, including severe human papillomavirus (HPV) disease. We did a retrospective analysis of severe HPV disease in a group of 41 patients with severe combined immune deficiency from one centre who were alive 10 years or longer after haemopoietic stem-cell transplantation. Nine of the 41 patients had extensive chronic HPV disease limited to the skin, with a median onset at 8 years after transplantation. Four had lesions typical of epidermodysplasia verruciformis, a rare genodermatosis. Transplant characteristics, immune status, and chimerism of these nine patients did not differ significantly from those of the other patients. The nine patients with HPV disease had severe combined immune deficiency associated with either common gammac receptor cytokine subunit or Janus kinase-3 (JAK-3) deficiency. By contrast, patients with other forms of severe combined immune deficiency did not have any signs of HPV disease. That genetic causes are the only predisposing factor to be identified for severe combined immune deficiency, suggests that natural-killer cells or gammac/JAK-3-dependent signalling in keratinocytes could have a role in anti-HPV immunity.

Human herpesvirus 8 (HHV-8)-associated peritoneal primary effusion lymphoma (PEL) in two HIV-negative elderly patients

Human herpesvirus 8 (KSHV/HHV-8) is associated with all forms of Kaposi sarcoma (KS), with a rare high-grade B-cell non-Hodgkin lymphoma characterized by serous effusions in body cavities called primary effusion lymphoma (PEL) and with some forms of multicentric Castleman disease (MCD). Although mostly observed during AIDS, such disorders have also been described with a lower incidence in human immunodeficiency virus-negative patients. We describe here the features of two novel cases of AIDS-unrelated PEL. Two patients, a 78-year-old man (case 1) and a 86-year-old woman (case 2), both of French origin, presented exudative ascitic effusion containing numerous KSHV/HHV-8(+) EBV(-) large lymphomatous cells of B-cell clonal origin, characterized by a CD45(+) CD30(+) CD19(-) CD20(-) immunophenotype. The PEL tumor cells harbored a homogenous and isolated trisomy 12 in case 1 and an aberrant expression of the T-cell lineage antigen CD7 in case 2. Both patients were lymphopenic at the time of PEL diagnosis and rapidly died with progressive lymphoma. Moreover, patient 2 had a previous history of classic KS and MCD clinically improved after treatment with all-trans-retinoid acid and a concomitant metastatic breast adenocarcinoma. Compared to AIDS-related PEL, these two cases displayed distinct features in particular the advanced age of patients, as observed for Mediterranean KS, and the absence of EBV coinfection.

Prognostic impact of p27KIP1 expression in cyclin D1 positive lymphoproliferative disorders

Nodal mantle cell lymphoma (MCL) is a well-defined entity, but non-nodal leukemic cyclin D1 positive lymphoproliferative disorders have been reported and their relationship with MCL remains controversial and their prognosis heterogeneous. We prospectively studied the expression of cyclin D1 in CD5 positive leukemic B lymphoproliferative disorders at diagnosis and identified 65 cases overexpressing cyclin D1. We did not distinguish any clinical or biological criteria allowing one to identify a non-MCL group. Multivariate analysis identified age, anemia and p27kip1 expression as independent prognostic factors of survival. By univariate analysis, p27kip1 high expression proved to be the strongest predictor of prolonged survival. The median survival of p27 low expressors was 30 months, while it was not reached for p27 high expressors. A high level of p27 expression was often found associated with the absence of nodal involvement and the presence of somatic mutations, but neither of them was restricted to the p27 high expression group. In conclusion, we hypothesize that MCL and these cyclin D1 positive leukemic lymphoproliferative disorders represent a continuous spectrum of diseases. Determination of p27 expression level appears as a routine applicable test allowing identification of a subset of patients who could be considered for different therapeutic approaches.

LMO2-associated clonal T cell proliferation in two patients after gene therapy for SCID-X1

We have previously shown correction of X-linked severe combined immunodeficiency [SCID-X1, also known as gamma chain (gamma(c)) deficiency] in 9 out of 10 patients by retrovirus-mediated gamma(c) gene transfer into autologous CD34 bone marrow cells. However, almost 3 years after gene therapy, uncontrolled exponential clonal proliferation of mature T cells (with gammadelta+ or alphabeta+ T cell receptors) has occurred in the two youngest patients. Both patients' clones showed retrovirus vector integration in proximity to the LMO2 proto-oncogene promoter, leading to aberrant transcription and expression of LMO2. Thus, retrovirus vector insertion can trigger deregulated premalignant cell proliferation with unexpected frequency, most likely driven by retrovirus enhancer activity on the LMO2 gene promoter.

CALM-AF10 is a common fusion transcript in T-ALL and is specific to the TCRgammadelta lineage

The t(10;11)(p13-14;q14-21) associated with CALM-AF10 is considered to be rare and associated with a variety of acute lymphoid and myeloid leukemias. Twelve (9%) of 131 unselected T-cell acute lymphoid leukemias (T-ALLs) expressed CALM-AF10 by reverse transcription-polymerase chain reaction or fluorescence in situ hybridization (or both), including 8% of children and 10% of adults, of whom only half demonstrated a t(10;11) by classical cytogenetics. CALM-AF10 was not found in T-cell-receptor alphabeta (TCRalphabeta) lineage T-ALLs, as defined by expression of TCRalphabeta, cytoplasmic TCRbeta, or TCRbetaVDJ rearrangement in immature cytoplasmic TCRbeta- cases, compared with 19% of TCRgammadelta T-ALLs and 33% of immature delta/gamma T-ALLs. The latter differed from their CALM-AF10- immature counterparts by a CD5+/CD2-phenotype, as found in TCRgammadelta but not TCRalphabeta T-ALLs and in their TCRgamma and TCRdelta configurations, altogether suggesting that CALM-AF10+ immature delta/gammaT-ALLs are TCRgammadelta precursors and that, within T-ALL, CALM-AF10 is specific for this lineage. Nine of 12 immature CALM-AF10 T-ALLs demonstrated 3' fusion transcripts, whereas 6 of 7 TCRgammadelta T-ALLs demonstrated 5' fusion transcripts. The latter retain the AF10 extended LAP/PHD domain necessary for homo-oligomerization. All 8 patients with CALM-AF10+TCRgammadelta T-ALLs are alive, compared with only 3 of 12 with immature CALM-AF10+ T-ALLs. Six CALM-AF10+ non-T acute leukemias all expressed CD7 and demonstrated T-restricted TCRdelta rearrangements, suggesting that they may also be related to the TCRgammadelta lineage. CALM-AF10 is therefore the most common fusion protein in T-ALL. It requires molecular and immunophenotypic characterization for appropriate prognostic evaluation and should be included in diagnostic screening panels of T-ALL and immature acute leukemias. Analysis of immature CALM-AF10+ leukemias will also facilitate analysis of the early stages of development of the TCRgammadelta lineage.

T-cell prolymphocytic leukemia with autoimmune manifestations in Nijmegen breakage syndrome

Nijmegen breakage syndrome (NBS) is characterized by growth retardation, microcephaly, mental retardation, immunodeficiency, and predisposition to malignancies, especially B-cell lymphomas. In contrast, leukemia is rare. A 23-year-old NBS patient presented with anemia, thrombocytopenia, and hyperlymphocytosis. The diagnosis of T-cell prolymphocytic leukemia (T-PLL) was confirmed by cytological and immunological assays (TdT(-), CD2(+), CD5(+), CD3m, and CD7(+)). Biological assays also showed a hemolytic anemia and a clotting factor V decrease. The patient was first treated by methylprednisone for 3 weeks. During this period the lymphocyte count decreased. The simultaneous normalization of the hemolysis and of factor V suggested that both could be related to T-PLL. Since T-PLL is refractory to conventional therapies with a poor prognosis, an intensive chemotherapy such as 2'-deoxycoformycin with anti-CDw52 monoclonal antibodies is usually favored. In the present case, however, because of the specific context (i.e., NBS-induced immunodepression, severe hemolytic anemia, and acquired factor V deficiency), he received pentostatin weekly during 1 month and in maintenance during 6 months. At last follow-up (7 months) he showed a persistent control of the lymphocytosis with no side effect.

Recurrent partial trisomy 1q22-q44 in clonal intraepithelial lymphocytes in refractory celiac sprue

BACKGROUND & AIMS

Refractory celiac sprue, a low-grade intraepithelial lymphoma characterized by expansion of clonal intraepithelial lymphocytes with intracellular CD3 epsilon but no surface CD3-T-cell receptor complexes, can be an intermediary step between celiac disease and overt T-cell lymphoma. To gain insight into the mechanisms of lymphomagenesis in celiac disease, we have performed the first cytogenetic study in refractory celiac sprue.

METHODS

Karyotypes were performed on: (1) 7 cell lines derived from clonal intraepithelial lymphocytes of patients with refractory celiac sprue; (2) 14 control T-cell lines, either from 4 of 7 patients with refractory celiac sprue or from 10 patients with uncomplicated celiac disease; and (3) bone marrow and peripheral blood lymphocytes in 1 of 7 patients with refractory celiac sprue. Rearrangements were confirmed by in situ hybridization using whole-chromosome painting probes and by comparative genomic hybridization in one patient.

RESULTS

A recurrent structural chromosomal aberration leading to partial trisomy of the long arm of chromosome 1 was found in 6 of 7 cell lines from patients with refractory celiac sprue but in none of the control T-cell lines. In one patient with circulating abnormal intraepithelial lymphocytes, the partial trisomy 1q was confirmed on cells freshly isolated from bone marrow and blood.

CONCLUSIONS

Refractory celiac sprue is strongly associated with partial trisomy of the 1q region. Gain of chromosome 1q, recently found in 16% of enteropathy-type T-cell lymphoma, may be an early event in lymphomagenesis related to celiac disease and provides a key to investigating molecular mechanisms of lymphoid transformation in this disease.

[Spectral karyotyping (SKY) principle, avantages and limitations]

Banding karyotype is a routine technique, which allows the identification of numerous aneusomy and/or aneuploïdy in congenital diseases and cancers. However, this analysis fails to detect small or complex chromosome rearrangements. Molecular cytogenetic techniques like fluorescence in situ hybridization (FISH) analysis can overlap these limitations. Particularly, multicolor karyotyping by spectral karyotyping (SKY) may rectify or precise the conventional karyotype results. With two examples, we present here, the principle, the indications and the limits of this technique for constitutional and cancer chromosomal abnormalities characterization. Moreover, we present an easy way to build efficient sky probes with a best sensitivity than the probes classically used.

Identical abnormality of the short arm of chromosome 18 in two Philadelphia-positive chronic myelocytic leukemia patients with erythroblastic transformation, resulting in duplication of BCR-ABL1 fusion

Two patients with Ph-positive chronic myelocytic leukemia in erythroblastic transformation and rearrangement of the short arm of chromosome 18 are reported. Fluorescence in situ hybridization studies showed that the 18p rearrangement resulted from translocation of the main part of chromosome 22 long arm to 18p, including BCR-ABL1 fusion. The 18p abnormality resulted, thus, in loss of 18p and duplication of BCR-ABL1 in both patients. The possible relation to the erythroblastic type of blastic phase is briefly discussed. In addition an apparently intact germline ABL1 gene was duplicated and inserted into chromosome 6 at band p21 in one of these patients.

CD4(+), CD56(+) DC2 acute leukemia is characterized by recurrent clonal chromosomal changes affecting 6 major targets: a study of 21 cases by the Groupe Français de Cytogénétique Hématologique

CD4(+), CD56(+) DC2 malignancies constitute a novel disease entity, which has recently been shown to arise from a transformed lymphoid-related plasmacytoid dendritic cell (DC2). Diagnosis is primarily based on a particular immunophenotype with tumor cells expressing CD4 and CD56 antigens in the absence of common lymphoid or myeloid lineage markers. Little is currently known about the cytogenetic features of this disease entity. In this setting, the Groupe Français de Cytogénétique Hématologique (GFCH) initiated a cytogenetic study of 18 adults and 3 children with CD4(+), CD56(+) DC2 acute leukemia using conventional and fluorescence in situ hybridization/24-color karyotyping. Clonal, mostly complex chromosome aberrations were found in 14 patients (66%). Six major recurrent chromosomal targets were defined. These were 5q, 12p, 13q, 6q, 15q, and 9, which were involved in 72% (5q), 64% (12p and 13q), 50% (6q), 43% (15q), and 28% (monosomy 9) of cases, respectively. Cytogenetic features can be summarized as follows: (1) gross genomic imbalances (mostly losses) predominate, (2) no single anomaly can be considered as specific, whereas their combination/accumulation is, and (3) both lymphoid and myeloid lineage-associated rearrangements are observed in unusual combinations in the same cell. This is suggestive of complex multistep tumorigenic mechanisms and is supportive of the hypothesis that CD4(+), CD56(+) DC2 acute leukemia may arise from an undifferentiated nonmyeloid nonlymphoid progenitor cell. In conclusion, the present study documents for the first time the existence of a characteristic cytogenetic profile for this novel disease entity.

Remission of transformed myelodysplastic syndrome with fibrosis after danazol therapy

Danazol has been used with success in some hematological diseases, but there is no report of this treatment in acute leukemia. We report here a case of remission of myelodysplastic syndrome with myelofibrosis in transformation after danazol therapy in a 72-yr-old man. The role of danazol in remission induction is briefly discussed.

Typical essential thrombocythaemia does not express bcr-abelson fusion transcript

Essential thrombocythaemia (ET) is a chronic myeloproliferative disorder (MPD) characterized by an elevated platelet count and no identifiable underlying primary cause. According to the diagnostic criteria of the Polycythemia Vera Study Group (PVSG), ET lacks features diagnostic for other MPDs, including the Philadelphia chromosome (Ph) or bcr-abl rearrangement. Recently, some authors have reported bcr-abl transcript positivity in ET patients, but these findings remain controversial. The aim of this study was to investigate whether the bcr-abl transcript could be found in ET patients and to verify the hypothesis of a new ET variant. ET patients (n = 121) with a median age at diagnosis of 55 years were enrolled. The bcr-abl transcript status was examined by multiplex reverse transcription-polymerase chain reaction. Only two cases were positive for bcr-abl, one of which had the Ph at diagnosis. The positive bcr-abl transcript was associated, in both cases, with mild basophilia at diagnosis. After a median follow-up of 43 months (0-309 months), two patients in the bcr-abl-negative group developed Ph and bcr-abl-negative acute myeloid leukaemia (AML). In contrast, one of the two patients in the bcr-abl-positive group died from AML 13 years after diagnosis. In conclusion, our data on a large group of patients shows the rarity of the bcr-abl transcript in well-established ET. However, a subset of patients with apparent ET and basophilia may express the transcript and may constitute a novel entity intermediate between chronic myeloid leukaemia (CML) and typical ET. A prospective study is warranted in order to define better the clinical and biological characteristics of bcr-abl-expressing ET.

Reassessment of childhood B-lineage lymphoblastic leukemia karyotypes using spectral analysis

We studied a stratified cohort of 51 childhood B-lineage acute lymphoblastic leukemias (B-ALLs) to evaluate the efficiency of spectral karyotyping (SKY) in the detection of chromosome aberrations previously diagnosed using chromosome banding and/or reverse transcriptase polymerase chain reaction. Despite the small number of cases analyzed, several important features emerge from the study: (a) The result of banding analysis was revised in two-thirds of the cases. Eighty-three chromosome anomalies previously undetected or not characterized using chromosome banding were identified by spectral karyotyping, even in patients with apparently normal karyotypes. (b) All hyperdiploidy cases showed one or more extra copies of chromosomes X, 14, and 21. (c) Two hidden rearrangements, a t(7;12)(?p12;p13), and a new translocation, a t(9;12)(q31;p13), both involving the TEL gene, were characterized. (d) Some cryptic rearrangements, such as the der(21) t(12;21) translocation, remained undetected. (e) No new recurrent chromosome anomalies were discovered with this technique. In conclusion, the present study confirms the efficiency of the SKY technique in resolving and characterizing many complex chromosome anomalies seen in childhood B-ALLs, but it raises questions about the ability of this technique to detect cryptic rearrangements, such as the t(12;21) translocation.