An acquired Robertsonian translocation in prolymphocytic leukemia: a case presentation and review

Robertsonian translocations between the acrocentric autosomes are the most common type of constitutional chromosome rearrangement in humans. However, Robertsonian translocations are very rarely acquired in cancer cells. We report a patient with prolymphocytic leukemia and an acquired Robertsonian translocation in the leukemic cells. The translocation was between chromosomes #13 and #15; t(13;15)(q11;p12). Two other cases of malignancy with an acquired Robertsonian translocation have been found, one being of the t(13;15) type, which accounts for only 1% of constitutional Robertsonian translocations. We propose, therefore, that although Robertsonian translocations are occasionally observed in cancer cells, they are very rarely acquired.     

Robertsonian (15q;15q) translocation in a child with Angelman syndrome: Evidence of uniparental disomy

A balanced Robertsonian translocation 45,XY,t(15q15q) was detected in a patient with mental retardation, microcephaly, and hypertonia. Deletion of the 15q11q13 region was unlikely based on fluorescence in situ hybridization studies that revealed hybridization of appropriate DNA probes to both arms of the Robertsonian chromosome. Inheritance of alleles from 13 highly polymorphic DNA markers on chromosome 15 showed paternal uniparental isodisomy. The clinical, cytogenetic, and molecular results are consistent with a diagnosis of Angelman syndrome. © 1996 Wiley-Liss, Inc.     

Chromosome stability is maintained by short intercentromeric distance in functionally dicentric human Robertsonian translocations

While the formation of a dicentric chromosome often leads to chromosome instability, human dicentric Robertsonian translocations usually remain stable. To investigate the basis for this stability, we have examined the centromeres of 15 structurally dicentric rob(13q14q) Robertsonian translocations using immunofluorescence and fluorescence in situ hybridization (FISH). The immunofluorescence detection of centromere protein C (CENP-C) was used as a marker for centromere function as CENP-C seems to play an essential role in kinetochore structure and stability and was previously shown to be absent from inactive centromeres. In all 15 translocation-containing cell lines, CENP-C was confined to only one of the centromeres of the translocation in a fraction of the cells analyzed. This suggests that centromere inactivation commonly occurs on dicentric Robertsonian translocations and may serve as one mechanism allowing for their stability. However, in the majority of the translocations (12 out of 15), a portion of the cells analyzed displayed CENP-C immunofluorescence at both centromeres, suggesting that both centromeres were active and that the translocation was functionally dicentric. The percentage of cells with CENP-C at both centromeres ranged from 2% to 82%. These results support the hypothesis that the close proximity of two functional centromeres on Robertsonian translocations allows them to remain stable.     

Familial D/D translocation t(13q;14q) Eight members in four generations

Eight family members spanning four generations were found to have 45 chromosome count D/D translocation identified by Giemsa-trypsin banding as t(13q;14q). The only mature male is believed to be infertile on the basis of a very low sperm count with reduced motility. This is believed to be related to the chromosome aberration and not to be coincidental. Aside from this, all were clinically normal except the index case, a young girl with unusual facies and moderate to severe retardation of growth and development. It is believed that her abnormalities were coincidental to the chromosome translocation and fortuitous in locating this family and initiating the pedigree. This example of essentially benign (some males are fertile) Robertsonian centric fusion in humans lends itself to interesting speculations about the results from chance matings between such translocation carriers.     

Correlation between losses of IGH or its segments and deletions of 13q14 in t(11;14) (q13;q32) multiple myeloma

Multiple myeloma (MM) is a malignancy of the plasma cells (PCs) characterized by a wide variety of genetic and chromosomal abnormalities. In recent years, major attention was drawn to the significance of chromosomal aberrations involving chromosome arm 13q and the IGH region on chromosome band 14q32 as a prognostic indicator in MM. In this study we applied a combined cell morphology and FISH method for the analysis of coexistence of t(11;14)(q13;q32) with deletions of the long arm of chromosome 13 (Δ13) in PCs from 51 MM patients using several probes for the 13q14, 11q13, and IGH regions. We found 15 different variants of the t(11;14) that are the consequence of different 11q13 breakpoints and various deletions of Variable (del IGH Var) or Constant (del IGH Const) IGH segments and also duplications and losses of the IGH gene on the normal nontranslocated chromosome 14 as well as IGH/Cyclin D1 (CCND1) fusion on der(14) and CCND1/IGH fusions on der(11). A strong association between Δ13 and specific variants of t(11;14) was found: variants with deletion of the IGH gene or its segments were found only in MM cases with deleted chromosome 13, while the common translocation t(11;14) was found only in the MM cases with normal chromosome arm 13q. In contrast, we did not find any association between Δ13 and deletions of the IGH gene or its segments in the MM patients with t(4;14)(p16;q32). © 2009 Wiley‐Liss, Inc.     

Gene dosage change of TPTE and BAGE2 and breakpoint analysis in Robertsonian Down syndrome

Only 4% of Down syndrome (DS) cases have a Robertsonian translocation (ROB). The aim of this study was to define the possible breakage area in 21p where ROB occurs. We prospectively and consecutively collected ten cases ROB DS from three medical centers. Of the ten DS children, six were de novo (60%), and four were due to paternal or maternal inheritance (40%). They consisted of four der(21q;21q), four der(14q;21q), one der(13q;21q), and one der(21q;22q). The origin of the extra chromosome 21q was maternal in five of six de novo ROB and paternal in one case. All four der(21;21) ROB DS were an isochromosome. The result of gene dosage change by real-time quantitative polymerase chain reaction (PCR) was compatible with array-comparative genomic hybridization in one case. We further used real-time PCR to detect the copy number of TPTE and BAGE2 located on 21p11 and SAMSN1 on 21q11. The ratio of copy number in 21p:21q was 1:3 in der(21q;21q) but 2:3 in der(13q;21q), der(14q;21q), and der(21q;22q). Our preliminary results demonstrated the critical breakpoint of chromosome 21 involving ROB might lie between BAGE2 and the centromere, located from 10.1 to 12.3 Mb.     

Molecular mapping of the chromosome 11 breakpoint of t(11;17)(q13;q21) in a t(11;14)(q13;q32)-positive B non-Hodgkin's lymphoma

The FAU gene is the cellular homologue of the viral FOX sequences in the genome of the Finkel-Biskis-Reilly murine sarcoma virus (FBR-MuSV); the viral FOX sequences have been shown to increase the transforming capacity of FBR-MuSV in vitro. The human FAU gene has recently been isolated, characterized, and mapped to chromosome band 11q13. Here, we report results of fluorescence in situ hybridization (FISH) analysis which indicate that the FAU gene maps proximally to the putative oncogene BCL1 at 11q13. Furthermore, we identified a t(11;17)(q13;q21) translocation in tumor cells of a t(11;14)(q13;q32)-positive B-cell non-Hodgkin's lymphoma patient by FISH analysis using a FAU containing cosmid clone as molecular probe and by double-colour chromosome painting analysis using chromosome 11- and chromosome 17-specific painting probes. The position of the chromosome 11 breakpoint of the t(11;17) translocation was pinpointed to a human DNA region around the FAU gene of about 40 kbp. © 1993 Wiley-Liss, Inc.     

A de novo translocation, 14q21q, with a microchromosome-14p21p

A familial translocation, t(14;21)(14p21p;14q21q), in a mother and her child is described. The translocation was ascertained through the birth of a Down syndrome baby with the chromosome constitution 47,XX,-14, +der 14, +der 21,t(14;21)(q11;p12) mat. A 1:3 segregation in the maternal meiosis is suggested for the evolution of the unbalanced chromosome state. The main translocated chromosome 14q21q mimics the product of a Robertsonian translocation, while the 14p21p chromosome has the morphology of a satellited microchromosome. The cytogenetic nature of this translocation is discussed.     

Paternal Robertsonian translocation t(13q;14q) and maternal reciprocal translocation t(7p;13q) in a couple with repeated fetal loss.

Marriages involving partners both of whom have abnormal karyotypes are rare and are usually ascertained because of a history of infertility, repeated abortions, or the birth of a balanced translocation carrier or chromosomally abnormal offspring. Abnormalities which have been noted include sex chromosome aberrations in both parents or a sex chromosome abnormality in one parent and an autosomal abnormality in the other. Four papers have reported balanced reciprocal autosomal translocations in both parents, two couples representing a first cousin marriage. We present a case of a paternal 13;14 Robertsonian translocation and a maternal (7p;13q) reciprocal translocation in a couple with repeated fetal loss.     

A de novo translocation, 14q21q,with a microchromosome—14p21p

A familial translocation, t(14;21)(14p21p;14q21q), in a mother and her child is described. The translocation was ascertained through the birth of a Down syndrome baby with the chromosome constitution 47,XX,-14, +der 14, +der 21,t(14;21)(q11; p12) mat. A 1:3 segregation in the maternal meiosis is suggested for the evolution of the unbalanced chromosome state. The main translocated chromosome 14q21q mimics the product of a Robertsonian translocation, while the 14p21p chromosome has the morphology of a satellited microchromosome. The cytogenetic nature of this translocation is discussed.     

Prader-Willi syndrome and Robertsonian translocations involving chromosome 15

A case of Prader-Willi syndrome is presented in which high resolution chromosome analysis revealed not only a familial Robertsonian translocation [t(13q15q)], but also a del(15) (q11.2q13) of the chromosome 15 not involved in the translocation. While there have been numerous reports of Robertsonian translocations involving chromosome 15 in patients with Prader-Willi syndrome, in this case, the Robertsonian translocation was shown to be unrelated to the clinical findings.     

De novo t(5p;21q) in a patient previously diagnosed as monosomy 21

In situ hybridization was used to characterize an undetected chromosome translocation in a child whose metaphase chromosome analysis in peripheral blood and in skin culture revealed apparent monosomy 21. The cytogenetic study revealed 45 chromosomes, and no other structural anomalies were detected with G banding. In situ hybridization of chromosome 21-specific probes to metaphase chromosomes and reverse banding from the proband showed a de novo translocation between chromosome 5 and chromosome 21.     

Centromere-telomere (12;8p) fusion, telomeric 12q translocation, and i(12p) trisomy

The concurrence of a short arm isochromosome and a translocation of the entire long arm of the same chromosome to a telomere of another chromosome, implying trisomy for 4p, 5p, 7p, 9p, 10p or 12p, has been described in 13 patients. We have now used fluorescence in situ hybrization (FISH) to better characterize one of these rearrangements in which 12q was translocated to 8pter, whereas 12p was converted into an isochromosome. An alphoid centromere-12 repeat gave a strong signal on the i( 2p) and a weak but distinct signal at the breakpoint junction of the der(8), whereas the pantelomeric probe revealed three clear hybridization sites on the der(8): one at each end and another at the breakpoint junction. These findings suggest that the prime event was a post-fertilization centric fission of chromosome 12 leading to the 12q translocation via a real centromere telomere fusion and the i(12p). Alternatively, the crucial event may have been a centromere telomere recombination. An interstitial telomere has been documented by means of FISH at the breakpoint junction of the sole derivative usually present in 20 constitutional translocations including eight with a jumping behavior. In addition, six other telomeric translocations defined by banding methods, including another case of 12q translocation/i(12p), have also been jumping ones. These telomeric translocations have been de noro events and their proneness to exhibit a jumping behavior appears to be independent of the involved chromosomes, size of the translocated segments, and concomitant abnormalities.     

Cytogenetic findings in a breast stromal sarcoma. Application of fluorescence in situ hybridization to characterize the breakpoint regions in an 11;19 translocation.

Cytogenetic analysis of a stromal breast sarcoma revealed a complex karyotype that included a reciprocal 11;19 translocation, along with multiple numerical changes, deletions, and other unbalanced structural rearrangements. Karyotypic abnormalities have not been reported previously in this rare neoplasm that arises from mesenchymal breast tissue, and the t(11;19) is of interest because various types of sarcoma are characterized by specific reciprocal translocations. Because of the pericentric nature of the breakpoints on chromosomes 11 and 19 in the t(11;19), classical cytogenetic banding could not reveal the centromeric origin of the translocation derivatives. Using nonisotopic in situ hybridization with chromosome 11 and 19 alpha-satellite probes, the centromere of each derivative chromosome was determined, and the rearrangement was interpreted as a balanced translocation, t(11;19)(q12 or q13.1;p12 or p13.1). This abnormality has not been described previously in any breast tumor.     

The X1X2Y sex chromosome system in the fish Hoplias malabaricus. I. G-, C- and chromosome replication banding

Hoplias malabaricus, a widely distributed neotropical fish (Central America to Argentina), may represent a group of distinct species showing diversified cytotypes with respect to chromosome number, morphology and sex systems. One of these karyotypic forms is characterized by an X₁X₁X₂X₂/X₁X₂Y sex chromosome system, with 2n= 40 and 39 chromosomes in females and males respectively. Analyses with G-, C- and chromosome replication banding permitted a better characterization of the sex chromosomes in this cytotype. The Y chromosome, unique in males, resulted from a translocation event between two biarmed chromosomes: one similar to chromosome 6 (X₁) and the other one similar to chromosome 20 (X₂), the latter corresponding to a probable identification. On the basis of the observed banding patterns, the Y chromosome may represent a stable dicentric, with an inactive centromere interstitially located on its long arm. The results are also related to a specific satellite DNA subfamily, previously characterized in Hoplias malabaricus, which appears to be associated with the X₁ chromosome.This revised version was published online in November 2005 with corrections to the Cover Date.     

Submicroscopic genomic imbalances in burkitt lymphomas/leukemias: Association with age and further evidence that 8q24/MYC translocations are not sufficient for leukemogenesis

Chromosome banding analyses reveal secondary chromosome abnormalities in addition to the MYC translocations t(8;14)(q24;q32), t(8;22)(q24;q11), and t(2;8)(p11;q24) in 60%–80% of Burkitt lymphomas/leukemias (BL). The high incidence of such aberrations indicates that additional changes are important, perhaps necessary, for malignant transformation, i.e., the 8q24/MYC rearrangements may not be sufficient. To investigate this possibility, we performed single nucleotide polymorphism (SNP) array analysis on 20 cases of 8q24/MYC‐positive BL. Nineteen (95%) harbored genomic imbalances; the only case without such aberrations displayed secondary changes by chromosome banding analysis. Thus, all BL cases had abnormalities in addition to the 8q24 translocation. The adult cases harbored more changes (median 3; range 1–21) than did the childhood cases (median 1.5; range 0–5) (P = 0.034). Several recurrent aberrations were detected by SNP array analysis, in particular losses of 6q14.1‐q22.33, 9p21.3, and 13q14.2‐q14.3, gains of 1q23.3‐q31.3, chromosome 7, 13q31.3, and partial uniparental isodisomies for 6p12.2‐pter, 9p23‐pter, and 17p11.2‐pter. The molecular genetic consequences of these changes include deletions of the CDKN2A and TP53 genes, and gains/losses of several genes, such as MIR17HG and E2F2K, involved in the MYC pathway. Thus, deregulation of the MYC pathway, both directly through the 8q24/MYC translocation and indirectly through secondary genomic imbalances, may be essential not only for the initiation but also for the progression of BL. © 2012 Wiley Periodicals, Inc.     

15q duplication associated with autism in a multiplex family with a familial cryptic translocation t(14;15)(q11.2;q13.3) detected using array-CGH

Autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders with a strong genetic aetiology. In approximately 1% of cases, duplication of the 15q11-13 region has been reported. We report the clinical, array-comparative genomic hybridization (CGH) and cytogenetic evaluation of two individuals from a multiplex family demonstrating autism due to a maternally inherited gain of 15q11-13. Our findings indicate that unlike most 15q11-13 gains, which are caused by interstitial duplication of this region or supernumerary marker chromosomes deriving from proximal 15q, the 15q gain in this family is the result of abnormal segregation of a cryptic familial translocation with breakpoints at 14q11.2 and 15q13.3. The affected members of this family were found to have a normal karyotype at >550 band resolution. This translocation was identified using the 1-Mb resolution whole genome array (Spectral Genomics). The affected individuals have a gain of seven clones from proximal 15q, a loss of two clones from proximal 14q and a gain of two clones from 6q. Fluorescent in situ hybridization (FISH) analysis with clones from chromosomes 14 and 15, combined with DAPI reverse banding, showed an abnormal karyotype with one normal chromosome 15 and the der(15) t(14;15)(q11.2.;q13.3), resulting in the gain of proximal 15q and the loss of proximal 14q in affected individuals. The duplication of two clones from 6q in the affected subjects was also found in unaffected members of the family. Our findings suggest that the gain of 15q in autism may in some cases be due to cryptic translocations with breakpoints in the pericentromic regions of chromosome 15 and a different acrocentric chromosome. Variation in the size of pericentromic regions of any acrocentric chromosome may justify karyotype and FISH studies of autistic probands and their parents using probes from the 15q proximal region to determine recurrence risk for autism in some families.     

Comparison of high resolution chromosome banding and fluorescence in situ hybridization (FISH) for the laboratory evaluation of Prader-Willi syndrome and angelman syndrome

The development of probes containing segments of DNA from chromosome region 15q11-q13 provides the opportunity to confirm the diagnosis of Prader-Willi syndrome (PWS) and Angelman syndrome (AS) by fluorescence in situ hybridization (FISH). We have evaluated FISH studies and high resolution chromosome banding studies in 14 patients referred to confirm or rule out PWS and five patients referred to confirm or rule out AS. In four patients (three from the PWS category and 1 from the AS group) chromosome analysis suggested that a deletion was present but FISH failed to confirm the finding. In one AS group patient, FISH identified a deletion not detectable by high resolution banding. Review of the clinical findings in the discrepant cases suggested that the FISH results were correct and high resolution findings were erroneous. Studies with a chromosome 15 alpha satellite probe (D15Z) on both normal and abnormal individuals suggested that incorrect interpretation of chromosome banding may occasionally be attributable to alpha satellite polymorphism but other variation of 15q11-q13 chromosome bands also contributes to misinterpretation. We conclude that patients who have been reported to have a cytogenetic deletion of 15q11-q13 and who have clinical findings inconsistent with PWS and AS should be reevaluated by molecular genetic techniques. © 1994 Wiley-Liss, Inc.     

t(2;14)(p13;q32): a recurring abnormality in lymphocytic leukemia. A Pediatric Oncology Group study.

Chromosome banding studies of 1,411 children with newly diagnosed acute lymphocytic leukemia (ALL) identified two patients with the t(2;14)(p13;q32) chromosome abnormality and a third patient with a complex three-way translocation involving the same breakpoints on chromosomes 2 and 14 but also involving chromosome 12 at band q11. The three cases demonstrated variability of immunophenotypes: one was a T-cell ALL, and two were early pre-B ALLs. All three patients achieved complete remissions and have remained in remission for 14-19 months.     

Acquired Robertsonian translocations in two leukemia patients.

Robertsonian translocations were observed in two leukemia patients. The first case was a patient with chronic lymphocytic leukemia, who was found to have a rare Robertsonian translocation der(14;15)(q10;q10). The second case, a patient with acute myeloid leukemia, had multiple Robertsonian translocations: der(15)t(13;15)(q11.1;p11.1), der(14;22)(q10;q10), and dic(21;22)(p11.1;p11.1). Acquired multiple Robertsonian translocations have not been reported previously in leukemia.