Three further cases of t(8;14)(q11.2;q32) in acute lymphoblastic leukemia

A case of B-cell acute lymphoblastic leukemia in a child with Down syndrome bearing a t(2;12)(p12;p13) involving ETV6 and biallelic IGH@ rearrangements

Background

Rearrangements involving ETV6 (12p13) are among the most common structural abnormalities in pediatric B-cell acute lymphoblastic leukemia (B-ALL) and involve numerous partner genes. Additionally, the t(8;14)(q11.2;q32), which can result in the placement of CEBPD (8q11.2) near the regulatory regions of IGH@ (14q32) and consequent overexpression of CEPBD, occurs at a higher frequency in individuals with Down syndrome-associated ALL (DS-ALL) compared to both the general and pediatric population. The coexistence of cytogenetically detectable ETV6 abnormalities and t(8;14)(q11.2;q32) is a rare occurrence in B-ALL and has only been reported in a single case in the literature.

Findings

Herein, we present a case of B-ALL in a 9-year old male with Down syndrome in which conventional cytogenetic analysis revealed two reciprocal translocations: a t(8;14)(q11.2;q32) and a t(2;12)(p12;p13). Interphase and metaphase fluorescence in situ hybridization (FISH) analysis using break apart probes confirmed the involvement of IGH@ and ETV6 in these translocations, respectively. Additionally, interphase FISH revealed a clonal subpopulation bearing biallelic IGH@ rearrangements not observed by conventional cytogenetic analysis.

Conclusions

To the best of our knowledge, this is the first reported case of B-ALL bearing an ETV6 translocation with a partner gene on the short arm of chromosome 2 confirmed by FISH. Additionally, it is the second reported case of t(8;14)(q11.2;q32)-ALL bearing a concomitant, cytogenetically detectable abnormality involving ETV6. This case provides insight into a novel translocation involving ETV6 as well as potentially unique and understudied mechanisms of clonal evolution in pediatric B-ALL.

Pediatric acute lymphoblastic leukemia with a t(8;14)(q11.2;q32): B-cell disease with a high proportion of Down syndrome: a Children's Oncology Group study

The rare translocation t(8;14)(q11.2;q32) has been described in patients with B-cell acute lymphoblastic leukemia (ALL), particularly patients with Down syndrome (DS). We describe patients with the t(8;14)(q11.2;q32) who were identified by the Children's Oncology Group (COG) ALL cytogenetics database, expanding our previous report of 10 patients with this translocation. Twenty-two such patients were treated with COG protocols. All patients had B-cell ALL, and seven (31.8%) had DS. None of the children with DS had an event; thus, these patients had a superior estimated 5-year event-free survival (EFS) compared to non-DS patients (100% vs. 50.1 ± 17.7%; P = 0.04). Only one patient (4.5%) had a concomitant Philadelphia chromosome t(9;22)(q34;q11.2). The cytogenetics data of two additional patients, who were not eligible for COG protocols, are also included in this report. In conclusion, ALL patients with the recurring translocation t(8;14)(q11.2;q32) have the B-cell phenotype and a high percentage have DS. Children with DS and the t(8;14)(q11.2;q34) have improved EFS using standard COG therapy compared to non-DS patients. We did not find an increased number of patients with a concomitant Philadelphia chromosome in this population.

Cytogenetic features of acute lymphoblastic and myeloid leukemias in pediatric patients with Down syndrome: an iBFM-SG study

Children with Down syndrome (DS) have a markedly increased risk of acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). To identify chromosomal changes cooperating with +21 that may provide information on the pathogenesis of these leukemias, we analyzed 215 DS-ALLs and 189 DS-AMLs. Unlike previous smaller series, a significant proportion of DS-ALLs had the typical B-cell precursor ALL abnormalities high hyperdiploidy (HeH; 11%) and t(12;21)(p13;q22) (10%). The HeH DS-ALLs were characterized by gains of the same chromosomes as non–DS-HeH, suggesting the same etiology/pathogenesis. In addition, specific genetic subtypes of DS-ALL were suggested by the significant overrepresentation of cases with +X, t(8;14)(q11;q32), and del(9p). Unlike DS-ALL, the common translocations associated with non–DS-AML were rare in DS-AML, which instead were characterized by the frequent presence of dup(1q), del(6q), del(7p), dup(7q), +8, +11, del(16q), and +21. This series of DS leukemias—the largest to date—reveals that DS-ALL is a heterogeneous disorder that comprises both t(12;21) and HeH as well as DS-related abnormalities. Furthermore, this analysis confirms that DS-AML is a distinct entity, originating through other genetic pathways than do non–DS-AMLs, and suggests that unbalanced changes such as dup(1q), +8, and +21 are involved in the leukemogenic process.

t(6;14)(p22;q32): a new recurrent IGH@ translocation involving ID4 in B-cell precursor acute lymphoblastic leukemia (BCP-ALL)

Translocations involving the immunoglobulin heavy chain locus (IGH@) at chromosome band 14q32 are common in mature B-cell neoplasms, but are rare in B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Here, we report the translocation, t(6;14)(p22;q32), involving IGH@ as a novel recurrent translocation in 13 BCP-ALL patients. Fluorescence in situ hybridization and long-distance inverse polymerase chain reaction (PCR) identified ID4 as the partner gene. Breakpoints were scattered over a 19kb region centromeric of ID4. Quantitative real-time PCR showed up-regulation of ID4 mRNA. All patients had deletions of CDKN2A and PAX5 located on the short arm of chromosome 9, frequently as a result of an isochromosome, i(9)(q10) (9/13, 69%). This study defines a new subgroup of BCP-ALL characterized by ID4 over-expression and CDKN2A and PAX5 deletions. Preliminary survival data suggest that this subgroup may be associated with a good response to therapy.

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.

Acute lymphoblastic leukemia characterized by t(8;14)(q11.2;q32)

The t(8;14)(q11.2;q32) is emerging as an uncommon, though recurrent cytogenetic finding. As of yet, too few cases of acute lymphoblastic leukemia (ALL) characterized by this translocation have been studied to determine its prognostic significance with confidence. We therefore report three new patients (two male children and one adult female) and present their hematologic, immunophenotypic, and clinical data. The clinical and laboratory characteristics of 26 other patients with t(8;14)(q11.2;q32) are summarized. The total number of patients now reported in the literature is 29 with a mean age of 14 years. Early relapse, that is, relapse within 6 months, does not appear to be a common feature of this group. The gender distribution is 19 males: 9 females (gender not reported in one case). Twenty-three t(8;14) patients show a pre-B immunophenotype and 24 of 24, on whom information is available, achieved complete remission after induction chemotherapy for B-ALL. Approximately one third of patients with t(8;14) have Down syndrome, 19 of 27 have additional acquired cytogenetic abnormalities, 5 of these have the t(9;22), and 4 show duplication of the abnormal chromosome 14, which is derived from the t(8;14). Hemoglobin and platelet counts are low at presentation in 10 of 10 and 8 of 9 patients, respectively, and the average white blood count is 38.9 x 10(9)/L. Of the 7 patients for whom IgH status has been determined, all show rearrangement of the IgH locus. Two of the present three patients are included in this group; their IgH rearrangement was demonstrated by fluorescence in situ hybridization with IgH break-apart probes.

t(14;19)(q32;q13): A recurrent translocation in B-cell precursor acute lymphoblastic leukemia

The recurrent t(14;19)(q32;q13) translocation associated with chronic B-cell lymphoproliferative disorders, such as atypical chronic lymphocytic leukemia, results in the juxtaposition of the IGH@ and BCL3 genes and subsequent overexpression of BCL3. We report six patients with B-cell precursor acute lymphoblastic leukemia who have a cytogenetically identical translocation with different breakpoints at the molecular level. Fluorescence in situ hybridization with locus-specific probes confirmed the involvement of the IGH@ gene but showed that the breakpoint on 19q13 lay outside the region documented in t(14;19)(q32;q13)-positive chronic lymphocytic leukemia. This newly described translocation constitutes a distinct cytogenetic subgroup that is confined to older children and younger adults with B-cell precursor acute lymphoblastic leukemia.