Supernumerary marker 15 chromosomes: a clinical, molecular and FISH approach to diagnosis and prognosis

Crolla, John A.; Harvey, John F.; Sitch, F.L.; Dennis, N R

doi:10.1007/bf00209395

Cited by 132 publications

(159 citation statements)

References 32 publications

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“…Two possible mechanisms have been proposed to explain the formation of SMC(15)s: a mechanism is based on NAHR between LCRs leading to the formation of a small dicentric and a large acentric chromosome which is subsequently lost. This recombination may occur either between homologues or between sister chromatids (18). Alternatively, a normal chromosome may undergo a premeiotic breakage losing a large segment of its long arm.…”

Section: Other Recurrent Inv Dup Del Chromosomesmentioning

confidence: 99%

Inverted duplications deletions: underdiagnosed rearrangements??

et al. 2009

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Molecular techniques led to the discovery that several chromosome rearrangements interpreted as terminal duplications were in fact inverted duplications contiguous to terminal deletions. Inv dup del rearrangements originate through a symmetric dicentric chromosome that, after asymmetric breakage, generates an inv dup del and a deleted chromosome. In recurrent inverted duplications the dicentric chromosome is formed at meiosis through non‐allelic homologous recombination. In non‐recurrent inv dup del cases, dicentric intermediates are formed by non‐homologous end joining or intrastrand annealing. Some authors hypothesized that in these cases the dicentric may have been formed directly in the zygote. Healing of the broken dicentric chromosomes can occur not only in a telomerase‐dependent way but also through telomere capture and circularization thus creating translocated or ring inv dup del chromosomes. In all the cases reported up to now, the duplicated region was always longer than the deleted one, but we can safely assume that there is another group of rearrangements where the deleted region is longer than the duplicated portion. In general, in these cases, the cytogeneticist will suspect the presence of a deletion and confirm it by FISH with a subtelomeric probe, but he/she will almost certainly miss the duplication. It is likely that the conventional analysis techniques used until now have led to a substantial underestimate of the frequency of inv dup del rearrangements and that the widespread use of array‐CGH in routine analysis will allow a more realistic estimate. Obviously, the concomitant presence of deletion and duplication has important consequences in genotype/phenotype correlations.

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Section: Other Recurrent Inv Dup Del Chromosomesmentioning

confidence: 99%

Inverted duplications deletions: underdiagnosed rearrangements??

et al. 2009

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“…19 ± 21 Two other breakpoint regions named BP4 and BP5 have been mapped distally to BP3, between markers D15S24 and D15S144, and seem to be implicated in cases of large 15q11-q14 duplications or triplications. 4,5,9,18,20,21 These distal regions appear to be more complex since breakpoint variability has been described (BP located distal to Figure 1 15q11-q14 chromosome rearrangements, breakpoint regions, and LCR15s clusters and copies. BP1 to BP5 breakpoints and class I (BP1) and class II (BP2) PWS/AS deletion types are shown.…”

Section: Introductionmentioning

confidence: 99%

Human chromosome 15q11-q14 regions of rearrangements contain clusters of LCR15 duplicons

et al. 2002

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Six breakpoint regions for rearrangements of human chromosome 15q11-q14 have been described. These rearrangements involve deletions found in approximately 70% of Prader-Willi or Angelman's syndrome patients (PWS, AS), duplications detected in some cases of autism, triplications and inverted duplications. HERC2-containing (HEct domain and RCc1 domain protein 2) segmental duplications or duplicons are present at two of these breakpoints (BP2 and BP3) mainly associated with deletions. We show here that clusters containing several copies of the human chromosome 15 low-copy repeat (LCR15) duplicon are located at each of the six described 15q11-q14 BPs. In addition, our results suggest the existence of breakpoints for large 15q11-q13 deletions in a proximal duplicon-containing clone. The study reveals that HERC2-containing duplicons (estimated on 50 ± 400 kb) and LCR15 duplicons (*15 kb on 15q11-q14) share the golgin-like protein (GLP) genomic sequence. Through the analysis of a human BAC library and public databases we have identified 36 LCR15 related sequences in the human genome, most (27) mapping to chromosome 15q and being transcribed. LCR15 analysis in non-human primates and age-sequence divergences support a recent origin of this family of segmental duplications through human speciation.

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“…Based on the parental origin, the larger markers are known to cause a phenotype involving ReDDy et al | Array CGH analysis of marker or ring chromosomes SyStematic Review some combination of mental retardation, seizures, autistic features, and growth retardation, whereas the latter are usually associated with a normal phenotype. [6][7][8] Similarly, FISH analysis of chromosome 22-derived markers can reveal whether the SMCs contain the critical region for cat eye syndrome (OMIM 115470), which is characterized by ocular coloboma and other dysmorphic features. 9 However, our knowledge on the clinical significance of the other sSMCs is limited.…”

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confidence: 99%