Jumping translocation in a newborn boy with dup(4q) and severe hydrops fetalis

Isochromosome Yp and jumping translocation of Yq resulting in five cell lines in an infertile male: a case report and review of the literature

Background

Jumping translocations are a rare type of mosaicism in which the same portion of one donor chromosome is translocated to several recipient chromosomes. Constitutional forms of jumping translocations are rare, and the 48 cases reported to date have been associated with both normal and abnormal phenotypes. Concurrence of isochromosome (i) of one arm and translocation of the other is also rare, with seven reported cases. We describe a unique case involving concurrence of i(Yp) and a jumping translocation of Yq to the telomere of chromosomes 12q and 17q, which resulted in five cell lines.

Case presentation

The patient, an otherwise healthy 35-year-old man, was referred for cytogenetic studies because of absolute azoospermia. He had elevated levels of follicle stimulating hormone and luteinizing hormone, consistent with abnormal spermatogenesis, and decreased levels of free testosterone and inhibin B. G-banded chromosome analysis revealed a mosaic male karyotype involving five abnormal cell lines. One of the cell lines showed loss of chromosome Y and presence of i(Yp) as the sole abnormality. Three cell lines exhibited jumping translocation: two involved 17qter, and the other involved 12qter as the recipient and Yq as the common donor chromosome. One of the cell lines with der(17) additionally showed i(Yp). The other der(17) and der(12) cell lines had a missing Y chromosome. All five cell lines were confirmed by FISH. Subtelomric FISH study demonstrated no loss of chromosome material from the recipient chromosomes at the translocation junctions.

Conclusions

We postulate that a postzygotic pericentromeric break of the Y chromosome led to formation of isochromosome Yp, whereas Yq formed a jumping translocation through recombination between its internal telomere repeats and telomeric repeats of recipient chromosomes. This in turn led to either pairing or an exchange at the complimentary sequences. Such translocation junctions appear to be unstable and to result in a jumping translocation. Cryptic deletion or disruption of AZF (azoospermic factor) genes at Yq11 during translocation or defective pairing of X and Y chromosomes during meiosis, with abnormal sex vesicle formation and consequent spermatogenetic arrest, might be the main cause of the azoospermia in our patient.

The conundrum of a jumping translocation (JT) in CVS from twins and review of JTs

Jumping translocations (JTs) are rare constitutional or acquired rearrangements involving a donor and several receiver chromosomes. They may be inherited or de novo. JTs can be found as a cultural artifact, in normal individuals or in pathological conditions. The clinical consequences range from spontaneous abortion, loss of fetus, chromosome syndrome, congenital abnormalities, and infertility to malignancy. Considering the breakpoints of JTs, they are localized predominantly in repeat regions such as pericentromeric, centromeric, subtelomeric, telomeric, and occasionally interstitial regions that may be in a low copy repeats (LCR) or in a telomere like sequence. Differences between the constitutional and acquired JTs donor breakpoints suggest an independent mechanism in their formation. In this review, a new JT involving a donor chromosome 18p10qter and recipients 17q25qter or 1q25qter found by CVS of a twin pregnancy is described. This case illustrates the diagnostic challenges posed by JTs.In this study, our knowledge on JTs is consolidated to improve identification, management, and counseling.

Jumping translocations

Jumping translocations (JT) are uncommon constitutional or acquired chromosome rearrangements involving one donor and several recipient chromosomes. They occur in various pathologic conditions and the mechanism of their formation remains elusive. A review of the literature showed that the major localizations of the breakpoints of JTs in human samples are nonrandomly located in pericentromeric and telomeric regions of chromosomes. Interestingly, comparison of the localization of the chromosomal breakpoints and of presence of interstitial DNA repeats showed differences between constitutional and acquired JTs suggesting differences in the mechanisms for the genesis of JTs and their consequences.

Prenatal diagnosis of jumping translocation involving chromosome 22 with ultrasonographic findings

We report on the prenatal diagnosis and ultrasonographic findings of a second-trimester fetus with jumping translocation involving chromosome 22. A 28-year-old gravida 2, partus 1, Turkish woman was referred for genetic counselling and ultrasonographic examination at 18 weeks' gestation because of a high risk of trisomy 21 in triple test. Prenatal ultrasonography showed tetralogy of Fallot with a diverticular dilatation of the pulmonary artery, flattened brow, complete absence of the right upper limb, hypospadias, oligodactyly (three digits) in left hand and in both feet, and hyperechogenic abdominal foci. Amniocentesis revealed a karyotype of 46,XY[4]/46,XY,-8,+ der(8),t(8;22)(q24.3;q11.21)[2]/45, XY,-22,-8,+ der(8)t(8;22)(q24.3;q11.21)[22]/45,XY,-22,-5,+ der(5)t(5;22)(q35.3;q11.21)[44]. A C-banding and FISH study with a specific centromeric probe (D14Z1/D22Z1) for chromosome 22 was made. In our case, partial monosomy for the regions 22q11.21-->22pter, 8q24.3-->8qter and 5q35.3-->5qter may partially explain the fetal malformations.

Duplication of chromosome region 4q28.3-qter in monozygotic twins with discordant phenotypes

We describe monozygotic twins with partially discordant phenotypes who were found to have a duplication of chromosome region 4q28.3-qter. The duplicated region of chromosome 4 resulted from an unbalanced segregation of a balanced maternal (4;22)(q28.3;p13) translocation. Duplication of the long arm of chromosome 4 has been described in >60 patients; however, it usually results from the unbalanced segregation of a parental balanced translocation and has an associated monosomy. Twenty cases of dup 4q without an associated monosomy have been reported, and this is the only case of dup 4q28. 3-qter. All cases of dup 4q are reviewed, and phenotypic aspects are analyzed. Issues of monozygotic twinning and other birth defects also are addressed.

Jumping translocations of 11q in acute myeloid leukemia and 1q in follicular lymphoma

Jumping translocation is a rare cytogenetic aberration in leukemia and lymphoma, and its etiologic mechanisms are not clearly known. We report two cases with jumping translocations. One had follicular lymphoma and jumping translocations of 1q onto the telomeric regions of 5p, 9p, and 15q in three cell lines, co-existing with the specific translocation t(14;18)(q32;q21). The second case had acute myeloid leukemia (AML) and jumping translocations of 11q as the sole aberration, onto multiple derivative chromosomes in each of the abnormal cells. A total of 17 telomeric regions were seen as the recipients of 11q in this case, and 9q was always involved as one of the recipients in all abnormal cells. Fluorescence in situ hybridization (FISH) confirmed the identification of 11q material in the derivative chromosomes. While 1q has been the most common donor of acquired jumping translocations, this is the first report on jumping translocations of 11q. Different from all previously reported jumping translocations which involve only one recipient in each cell line and lead to a mosaic trisomy, multiple recipients in most of the abnormal cells in this case had led to a tetrasomy, or a pentasomy of 11q. The pattern of chromosome involvement as the recipients of 11q appears to show a continuing evolutionary process of jumping, stabilization, and spreading of the donor material into other chromosomes. Somatic recombinations between the interstitial telomeric or subtelomeric sequences of a derivative chromosome and the telomeric sequences of normal chromosomes are believed to be the underlying mechanism of jumping translocations and their clonal evolution.

Jumping translocations involving 11q in a non-Hodgkin lymphoma

This paper presents the results of a cytogenetic analysis in an 11-year-old boy with non-Hodgkin lymphoma. The investigation was performed on slides obtained from short-term culture of lymph node cells. The analyses revealed an abnormal clone with loss of Y, gain of an X chromosome, t(3;22), trisomy 11, and three cytogenetically-related subclones with jumping translocations involving 11q13 as the common breakpoint region. This region is an unusual site of chromosome breakage in jumping translocations, and has not been reported thus far. Contrary to most published reports, the jumping translocation in our patient is associated with long survival.

Jumping translocations of 3q in acute promyelocytic leukemia

Jumping translocation is a rare phenomenon, seldom reported to occur in cancer. A complex four-way translocation involving chromosomes 3, 9, 15, and 17 was identified in the chromosome study on a patient with a history of an acute promyelocytic leukemia (APL). In the follow-up studies, the same complex rearrangement exhibited a jumping translocation between chromosomes 3 and 9 in one clone and 3 and 6 in another clone. This is the first reported case of jumping translocation in APL.

Jumping translocation with partial duplications and triplications of chromosomes 7 and 15

We report a 2-year-old female with seizures, mild dysmorphic features and a jumping translocation involving chromosome 15 that results in multiple cell lines with partial duplications and triplications of chromosomes 7 and 15. Fluorescent in situ hybridization (FISH) and chromosome microdissection were used to identify the complex nature of the jumping translocation. Interstitial telomeres were observed at the jumping translocation sites. The jumping chromosome rearrangement was also found to have a partial duplication of 7p as demonstrated by chromosome microdissection. Despite these partial duplications and triplications of chromosomes 7 and 15, the child does not have major birth defects. She does have mild sensorimotor delays. A review of non-Robertsonian jumping translocations is provided.

Fluorescence in situ hybridization assessment of the telomeric regions of jumping translocations in a case of aggressive B-cell non-Hodgkin lymphoma

We report a jumping translocation involving a donor chromosome 1 long arm in a case of aggressive B-cell non-Hodgkin lymphoma (NHL). Conventional cytogenetic banding studies demonstrated a breakpoint distal to the heterochromatic region of the donor 1q chromosome. Characterization by fluorescence in situ hybridization (FISH) of the jumping translocation demonstrated an apparent telomeric sequence loss of the recipient chromosomes. Additional cytogenetic aberrations, including the t(18;22) translocation associated with non-Hodgkin lymphoma, were also observed in this case. Cytogenetically similar cases of jumping translocations reported in the literature have implicated a preferential involvement of the donor chromosomes' heterochromatic regions and the telomeric regions of the recipient chromosomes. Jumping translocations are still considered rare and their appearance is associated with a poor prognosis. The presence of these specific findings for this case are discussed and compared with those previously reported in other hematologic disorders.

Jumping translocation in a phenotypically normal female

"Jumping translocation" jt refers to a rare type of chromosome mosaic, in which the same portion of a (donor) chromosome is translocated to different (recipient) chromosome sites. Jt have mainly been observed in lymphocyte cultures of patients with hematologic malignancies. We report a phenotypically normal female carrying a mosaic of two cell lines with the Xq26-qter segment translocated to the short arm of chromosomes 15 or 21 in peripheral blood lymphocytes. In skin fibroblasts, only the X/21 translocation was detected. We speculate that recombination between homologous repetitive sequences on non-homologous human acrocentrics may be the cause of such chromosomal rearrangements.