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

Abstract

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.

De Novo Unbalanced Translocations in Prader-Willi and Angelman Syndrome Might Be the Reciprocal Product of inv dup(15)s

“…In case 2, the translocation was “jumping” with a portion of 15q1-qter transposed to two different chromosomes in independent cell lines, suggesting that the acentric/neocentric chromosome had been preserved for a given, presumably short, period in embryogenesis. The finding that other jumping translocations have been reported with apparently the same portion of 15q1 translocated to up to three or even four different recipient chromosomes [29], [30] might reflect the persistence of an acentric/neocentric chromosome breaking down independently in separate early embryo cells and donating slightly dissimilar portions to different chromosomes. In this light, jumping translocations should not be considered as the result of the transposition of the same chromosomal portion to different chromosomes in different cells but rather as the result of distinct events of trisomy rescue.…”

Distinct karyotypes in two offspring of a man with jumping translocation karyotype 45,XY,der(16)t(16;22)(q24;q11.2), −22 [59]/45,XY,der(1)t(1;22)(p36;q11.2), −22 [11]/45,XY,der(22)t(22;22)(p13;q11.2), −22 [10]

“…However many non-genetic factors can lead to mitotic errors, such as radiation, toxic agents, oxidative stress [Tarin, 1996], compromised mitochondria [Keefe et al, 1995], or telomere shortening [Keefe et al, 2006]. Most of the identified JTs are de novo [Reddy, 2010]. Here, to our knowledge this is the first-described familial cases including a man and his daughter involving 22q11 and the five recipient chromosomes who both displayed different karyotypes from a jumping translocation in the peripheral blood.…”

Identification of a jumping translocation following pre‐implantation genetic diagnosis

“…It has been proposed that non-allelic homologous recombination (NAHR) between highly repetitive sequences involving low copy repeats (LCRs) may be involved in the formation of JTs [Stankiewicz et al, 2003]. In a review of JTs by Reddy [Reddy, 2010] the 22q11 region was involved in 9 out of 49 cases reviewed (14%). Our case provides further support for instability of the 22q11.2 region, with likely interchromosomal recombination due to NAHR occurring in paternal male meiosis between the der(4)t(4;22) and one chromosome 12 producing an unexpected der(12)t(12;22) karyotype in the offspring.…”