Distinct breakpoints in band 11q23 of the t(4;11) and t(11;14) associated with leukocyte malignancy.

Several non-random translocation breakpoints associated with leukemia or lymphoma have been shown to occur in chromosome band 11q23 between the genes CD3G and PBGD, a distance of approximately 750 kb. A combination of yeast artificial chromosome (YAC) cloning, in situ hybridization, and pulsed field gel electrophoresis (PFGE) experiments has further refined the interval containing one of these breakpoints, t(4;11)(q21;q23), to within 200 kb of CD3G. We have extended the PFGE analysis to show that the t(4;11) breakpoint lies in a region of approximately 100 kb, situated 100 kb distal to CD3G. Furthermore, we show that a second 11q23 breakpoint, t(11;14)(q23;q32), which was also previously mapped between CD3G and PBGD, is distinct from that of the t(4;11) chromosome. The 11q23 sequences that are involved at the t(11;14) breakpoint are not present in a YAC containing the t(4;11) breakpoint. The t(11;14) breakpoint has been localized on the PFGE map of the CD3G-PBGD interval and is at least 110 kb distal to the t(4;11) breakpoint, thus demonstrating heterogeneity among 11q23 breakpoints.     

Molecular analysis of a t(11;14)(q23;q11) from a patient with null-cell acute lymphoblastic leukemia

/1p;&-3qChromosome 11, band q23, is the frequent site of recurring cytogenetic rearrangements in human leukemia. We have cloned and sequenced the breakpoint junctions from a patient who had null-cell acute lymphoblastic leukemia (ALL) with a t(11;14)(q23;q11). The chromosome 14 breakpoints occurred within the TCRD locus, close to two diversity segments. The chromosome 11 breakpoint occurred between two head-to-head heptamer sequences, and junctional diversity was evident at both derivative junctions, suggesting involvement of the V(D)J recombinase. The TCRA/D locus on the normal chromosome 14 had undergone a Vδ2-Dδ3-ΨJα joining. Two phage clones with this VDJ rearrangement were isolated; one of these contained an intra-Jα region deletion. Two clones with the derivative 11 junction were isolated; one of these had a similar, but not identical, deletion. A heptamer-nonamer recognition sequence (located ～70 kb 5′ to Cα), not associated with a TCR gene coding segment, was found in the immediate vicinity of both 5′ breakpoints. We have designated this sequence 5′^del for 5′ deleting element. An intra-Jα region deletion involving this heptamer-nonamer was previously identified in the leukemia cells recovered from a patient who had T-cell ALL. Fifty kilobases of DNA on 11q23 surrounding the breakpoint were cloned and analyzed. No CpG islands or conserved sequences were identified within this region. Fluorescence in situ hybridization analysis showed that this 11q23 breakpoint mapped distal to the MLL gene associated with the recurring breakpoints in the 4;11, 9;11, and 11;19 translocations, distal to the RCK gene associated with an 11;14 translocation, and proximal to the ETSI gene, which is located at 11q24. © 1993 Wiley-Liss, Inc.     

Spontaneous expression of fra(11)(q23) in a patient with Ewing's sarcoma and t(11;22)(q23;q11)

Cytogenetic analysis of a Ewing's sarcoma revealed a 46,XX,t(8;18)(q11;q21.3), t(11;22)(q23–24;q11–12) chromosome pattern. Observation of t(11;22) is consistent with other reported cases of Ewing's sarcoma. One breakpoint in this translocation, 11q23, coincides with the location of a folate-sensitive fragile site. Examination of peripheral blood leukocyte chromosomes from the patient revealed a 46,XX chromosome pattern with spontaneous, fluorodeoxyuridine-, and Bactrim-induced expression of fra(11)(q23). This may be the first demonstration of constitutional fra(11)(q23) expression in a patient with a neoplasm that exhibits a chromosome rearrangement involving this breakpoint and the first observation of spontaneous expression of this fragile site. These results provide a basis for discussion of the relationship between fragile sites and chromosome rearrangements.     

A new case of translocation t(6;11)(q21;q23) in a therapy-related acute myeloid leukemia resulting in an MLL–AF6q21 fusion

A new case of translocation t(6;11)(q21;q23) in a patient with therapy-related acute myeloblastic leukemia is reported. The translocation results in fusion of the MLL and AF6q21 genes. The breakpoint with AF6q21 is located within the sequences encoding the AF6q21 fork head motif. The similar location of the localization of the chromosome 6 breakpoints in the present case and in the first case reported suggests their nonrandom localization. In addition, treatment for Hodgkin's disease prior to leukemia in both t(6;11)(q21;q23) cases suggests an association of this translocation with therapy-related leukemias, as reported for the recently described t(11;16)(q23;p13.3). Genes Chromosomes Cancer 22:221–224, 1998. © 1998 Wiley-Liss, Inc.     

A novel t(2;6)(p12;q23) appearing during transformation of follicular lymphoma with t(18;22)(q21;q11) to diffuse large cell lymphoma

Follicular lymphoma is characterized genetically by t(14;18)(q32;q21), whereas t(18;22)(q21;q11), a rare variant form of t(14;18), has been preferentially observed in chronic lymphocytic leukemia (CLL). We describe here an unusual case of follicular lymphoma with a t(18;22)(q21;q11), that progressed to diffuse large cell lymphoma with a novel t(2;6)(p12;q23). Spectral karyotyping revealed that add(2)(p12) and add(6)(q23) were derived from a t(2;6)(p12;q23). Fluorescence in situ hybridization analysis confirmed rearrangements of the BCL2 gene at 18q21 and the BCL6 gene at 3q27. Our results indicate that a reciprocal translocation involving 6q23 could be implicated in the progression of follicular lymphoma and that t(18;22) may have a specific role in the pathogenesis of follicular lymphoma as well as CLL.     

Hu-ets-1 gene in congenital leukemia with t(11;19)(q23;p13)

Cytogenetic analysis of the leukemic cells from a 1-day-old baby with an acute myelomonocytic leukemia revealed them to contain a chromosome change of t(11;19)(q23;p13). Molecular studies using a 980 bp HindIII/HpaI digested v-ets probe showed no DNA rearrangements, deletions, or amplification in the leukemic cells, including the JH immunoglobulin and T-cell receptor ( or β) genes. The findings indicate that the leukemic cells with t(11;19)(q23;p13) appear not to contain a transposition or rearrangement of the protooncogene Hu-ets-1 located at 11q23, as previously described in leukemic cells with t(4;11)(q21;q23) and t(9;11)(p22;q23). The leukemic cases with t(11;19)(q23;p13) studied by us showed a phenotype compatible with their myelomonocytic nature, although it is possible that other cases may have a lymphoid phenotype.     

Regions of genomic instability on 22q11 and 11q23 as the etiology for the recurrent constitutional t(11;22)

The constitutional t(11;22)(q23;q11) is the only known recurrent, non-Robertsonian translocation. To analyze the genomic structure of the breakpoint, we have cloned the junction fragments from the der(11) and der(22) of a t(11;22) balanced carrier. On chromosome 11 the translocation occurs within a short, palindromic AT-rich region (ATRR). Likewise, the breakpoint on chromosome 22 has been localized within an ATRR that is part of a larger palindrome. Interestingly, the 22q11 breakpoint falls within one of the 'unclonable' gaps in the genomic sequence. Further, a sequenced chromosome 11 BAC clone, spanning the t(11;22) breakpoint in 11q23, is deleted within the palindromic ATRR, suggesting instability of this region in bacterial clones. Several unrelated t(11;22) families demonstrate similar breakpoints on both chromosomes, indicating that their translocations are within the same palindrome. It is likely that the palindromic ATRRs produce unstable DNA structures in 22q11 and 11q23 that are responsible for the recurrent t(11;22) translocation.     

CD3G is within 200 kb of the leukemic t(4;11) translocation breakpoint.

The t(4;11)(q21;q23) has been associated with acute lymphocytic leukemia (ALL) especially in infants. The t(4;11) breakpoint on chromosome 11 is cytogenetically indistinguishable from breakpoints for other leukemia-associated translocations affecting 11q23. The molecular basis of the t(4;11) is unknown although a number of genes have been mapped to 11q23. The CD3D, G, and E genes have been positioned proximal to the 11q23 breakpoint of the 4;11 translocation while the THY1 and ETS1 genes have been mapped distal to this breakpoint. We report evidence that CD3G is within 200 kb of the 4;11 breakpoint as observed by pulsed field gel analysis. A rearrangement of the CD3G gene has been observed in a cell line derived from a patient with the t(4;11) translocation and in a hybrid cell line containing the derivative 11q chromosome derived from this cell line, using the restriction enzymes SacII and ClaI. Similar rearrangements using SacII were observed in 2 further patients with ALL and the t(4;11) translocation. No rearrangements in the same DNA were observed using ETS1, THY1, and D11S29 and a range of rare cutter restriction enzymes. CD3G thus provides a tool for the cloning and analysis of the 4;11 translocation, and poses a question of its possible involvement at long range with this translocation.     

Restricted chromosome breakpoint sites on 11q22-q23.1 and 11q25 in various hematological malignancies without MLL/ALL-1 gene rearrangement

We analyzed 32 patients with various hematological malignancies including acute myelocytic leukemia and non-Hodgkin lymphoma with a breakpoint at 11q22-q25 of chromosome 11, but who did not have rearrangements of the MLL/ALL-1 gene. The breakpoint in each patient was identified by fluorescence in situ hybridization using 21 cosmid probes and 2 YAC probes. Breakpoints for each "rearrangement" involving translocations such as t(1;11), t(2;11), inv(11), t(11;15), and t(10;11) found in 5 of the 11 patients had breakpoints in a small region from Ccl11-430 to Ccl11-526 at 11q22-q23.1. Furthermore, breakpoints for chromosome deletions at 11q21-q23 in 10 patients were located in the same region as that of translocations. A commonly deleted region among 8 patients was identified from Ccl11-526 to Ccl11-555 at 11q23.1. Fluorescence in situ hybridization analysis revealed that breakpoints for additive chromosome [add(11)] aberrations, which had additional material of unknown origin at 11q23 to 11q25 in 11 patients, were not located at 11q23 but rather at the more telomeric site of Ccl11-503 to VIJ(2)2072 at 11q25. These results indicated that the patients had several restricted breakpoint sites, which means that these chromosomal regions have recurrent oncogenes and tumor suppressor genes for pathogenesis for leukemia and lymphoma.     

t(11;19)(q23;p11) in a child with acute T-cell leukemia

A translocation, t(11;19)(q23;p11), is reported in a child with T-cell leukemia. Our case indicates that the t(11;19) may not be restricted to the monocytic leukemias, as earlier reported, but may occur in other malignancies.     

Molecular cytogenetics localizes two new breakpoints on 11q23.3 and 21q11.2 in myelodysplastic syndrome with t(11;21) translocation.

Translocation t(11;21)(q24;q11.2) is a rare but recurrent chromosomal abnormality associated with myelodysplastic syndrome (MDS) that until now has not been characterized at the molecular level. We report here results of a molecular cytogenetic analysis of this translocation in a patient with refractory anemia. Using FISH with a panel of 11q and 21q cosmid/YAC probes, we localized the chromosome 11 breakpoint at q23.3 in a region flanked by CP-921G9 and CP-939H3 YACs, distal to the HRX/MLL locus frequently involved in acute leukemias. The chromosome 21 breakpoint was mapped in a 800-kb fragment inserted into the CP-145E3 YAC at 21q11.2, proximal to the AML1 gene. It is noteworthy that in all four cases with a t(11;21) reported until now, a second der(11)t(11;21) and loss of normal chromosome 11 could be observed either at diagnosis or during the course of the disease. Since in our case heteromorphism was detected by FISH on the centromeric region of the two der(11), the second der(11) chromosome could be the result of a mitotic recombination that had occurred on the long arm of chromosome 11, rather than of duplication of the original der(11). Constancy of secondary karyotypic changes resulting in an extra copy of the putative chimeric gene at der(11), loss of 11 qter sequences, and partial trisomy 21 suggest that neoplastic progression of MDS cases with a t(11;21) may be driven by the same mechanism(s).     

t(9;11)(p22;q23) translocation in blastic phase of chronic myeloid leukemia.

A patient with chronic myeloid leukemia showed clonal karyotypic evolution, with the appearance of an i(17q) and t(9;11)(p22;q23). This case sheds light upon leukemogenic events related to t(9;11)(p22;q23). The presence of t(9;22) and t(9;11) in the same clone showed that t(9;11) may affect a pluripotent stem cell, thus accounting for t(9;11) in both lymphoid and monocytic leukemias. In this patient, t(9;11) could not be related to a prior cytotoxic exposure and was instead the result of natural evolution of chronic myeloid leukemia. Furthermore, this led us to assume that the phenotype of blast cells may be determined by a chromosome abnormality. A phenotypic conversion from myeloblastic to undifferentiated morphologic aspect was observed when t(9;11) was detected, suggesting that t(9;11) may have induced a loss in differentiation of blast cells affected by this change. This assumption is in agreement with the putative presence of genes activated in pluripotent progenitors by 11q23 rearrangements.     

New complex t(2;11;17)(p21;q23;q11), a variant form of t(2;11), associated with del(5)(q23q32) in myelodysplastic syndrome-derived acute myeloblastic leukemia

The t(2;11)(p21;q23) is a rare recurrent aberration observed in myelodysplastic syndrome (MDS) and acute myeloblastic leukemia (AML). It has been suggested that t(2;11) is specifically associated with a deletion of the long arm of chromosome 5 (5q). A 63-year-old man was initially diagnosed as AML with del(5)(q23q32) as a sole abnormality. At relapse, t(2;11;17)(p21;q23;q11) in association with del(5q) appeared in 14 of 20 cells by G-banding. Spectral karyotyping confirmed three derivative chromosomes, der(11)t(2;11), der(17)t(11;17), and der(2)t(2;17). Fluorescence in situ hybridization analysis with a probe for MLL demonstrated that the breakpoint at 11q23 was telomeric to the MLL gene. Nine of 10 reported cases with t(2;11) and del(5q) had MDS including 5q- syndrome and four of them evolved to AML, as observed in the present case. Our results indicated that t(2;11;17) was a secondary genetic change, which appeared during disease progression after del(5q) was observed. Furthermore, considering another reported case, the MLL gene seems to be not involved in the pathogenesis of MDS/AML with t(2;11) and del(5q).     

t(6;12)(q23;q13) and t(10;16)(q22;p11) in a phyllodes tumor of breast.

Cytogenetic analysis of short-term cultures from a phyllodes tumor showed clonal chromosome changes including t(6;12)(q23;q13) and t(10;16)(q22;p11). This is the first reported karyotype in this tumor type. We discuss the breakpoints of these translocations in relation to the involvement of possible candidate genes.     

A novel t(2;3)(p11;q27) in a case of follicular lymphoma

Rearrangement of the BCL6 gene is found in follicular lymphomas and in diffuse large B cell lymphomas of follicular center cell origin. The breakpoints cluster mainly in a region spanning the first noncoding exon of the gene (the major breakpoint region). A second breakpoint cluster has also been identified upstream of the first BCL6 noncoding exon (the alternative breakpoint region [ABR]). To date, eight different rearrangements involving the ABR have been reported. Here, we describe a novel rearrangement involving a t(2;3)(p11;q27) translocation that affects the ABR in an unusual combination with the IGK locus.     

Chromosome 18 breakpoint in t(11;18)(q21;q21) translocation associated with MALT lymphoma is proximal to BCL2 and distal to DCC

The t(11;18)(q21;q21) translocation has recently been identified as a recurring chromosomal abnormality in a subset of extranodal marginal zone B‐cell lymphoma, a low‐grade lymphoma of mucosa‐associated lymphoid tissue (MALT). Neither the 11q21 nor the 18q21 breakpoints have been characterized by molecular genetic analysis. As a prelude to isolation of the gene(s) involved in this translocation, we have mapped the 18q21 breakpoint region by fluorescence in situ hybridization (FISH) of YAC and PAC clones. We mapped 37 YACs assigned to a 29‐cM region within the chromosomal band 18q21. Using nine of these YACs in single‐ and/or dual‐color FISH to analyze three cases of MALT lymphomas with the t(11;18)(q21;q21) translocation, we localized the breakpoints within a 1.6‐Mb nonchimeric YAC (938E1). This YAC is useful for the detection of the translocation in metaphase and in interphase cells. A nonchimeric YAC contig of an 8‐cM region around the breakpoint comprising nine YACs and a PAC contig of YAC 938E1 were constructed, which enabled the refinement of the breakpoint region in the proximal region of the YAC within a <820‐kb segment. This breakpoint is proximal to the BCL2 locus and distal to DCC and DPC4 loci in chromosomal band 18q21. Genes Chromosomes Cancer 24:156–159, 1999. © 1999 Wiley‐Liss, Inc.