Characterization of Small Supernumerary Marker Chromosomes By A Simple Molecular and Molecular Cytogenetics Approach

Liehr, Thomas; Trifonov, Vladimir A.; Polityko, A; Brecevic, Lukrecija; Mrasek, Kristin; Weise, Anja; Ewers, Elisabeth; Reich, Daniela; Iourov, Ivan Y.; Mkrtchyan, Hasmik; Manvelyan, Marina; Kosyakova, Nadezda

doi:10.2478/v10034-007-0006-5

Cited by 2 publications

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References 19 publications

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“…The risk for clinically abnormal phenotypes of SMCs ascertained in de novo prenatal cases is 7% for the SMCs from acrocentric autosomes and 28% from non-acrocentric autosomes. 4,5 About 30-50% of pregnancies diagnosed with SMCs go for termination due to lack of insight about the outcome of the SMCs. 2 In the past, identification of the SMCs was done by Fluorescence in situ hybridisation (FISH).…”

Section: Introductionmentioning

confidence: 99%

Molecular characterization of supernumerary marker chromosomes found as unexpected chromosome abnormalities in nine prenatal and nine postnatal samples

Lall¹,

Joshi²,

Agarwal³

et al. 2019

OGIJ

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Objectives:The supernumerary marker chromosomes (SMCs) are extra structurally abnormal chromosomes that cannot be unambiguously identified or characterised by conventional karyotyping. Their clinical phenotypes are variable and are dependent on their size, gene content, inheritance and level of mosaicism. In the past, fluorescence in situ hybridization (FISH) and related techniques were used to identify the chromosome origin, but the molecular makeup was still unknown. Chromosome microarray analysis (CMA) can detect the exact genomic breakpoints and gene content of the SMC. This can be correlated with the phenotype for better genetic counselling Methods: In the last 5 years, out of 20,000 samples referred for various reasons for karyotyping, we found 18 SMCs (0.09%) as unexpected results, nine were prenatal samples and nine were postnatal. All eighteen samples were subjected to CMA to characterize the SMCs. FISH was done for identification or validation, wherever possible.Results: Out of 18 SMCs, 14 were successfully characterized: eight (57.14%) were acrocentric chromosomes [seven der(15) and one der (22)], five (35.71%) were nonacrocentric chromosomes [der(9) , der(11), der(12), two der(18)] and one (7.14%) was a complex, novel SMC originating from the maternal translocation t(10;13). The remaining four were very small and heterochromatic with normal array reports.Seven had SMC-related known syndromes such as 15q11q13 duplication syndrome (n=2), Cat Eye syndrome, Trisomy 9p syndrome, i(12)p Pallister Killian syndrome and the rare Trisomy 18p syndrome(n=2). Conclusion:The results, their molecular relevance and pathological significance for genetic counselling were discussed case by case individually. The study emphasizes the usefulness of CMA in identification and characterization of the additional genetic material of the SMC which can be correlated with the phenotypes of the postnatal patient for future management and also the clinical significance conveyed to the parents when the SMC is found in the prenatal samples.

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Section: Introductionmentioning

confidence: 99%

Molecular characterization of supernumerary marker chromosomes found as unexpected chromosome abnormalities in nine prenatal and nine postnatal samples

Lall¹,

Joshi²,

Agarwal³

et al. 2019

OGIJ

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Identification of small marker chromosomes using microarray comparative genomic hybridization and multicolor fluorescent in situ hybridization

et al. 2016

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BackgroundMarker chromosomes are small supernumerary chromosomes that cannot be unambiguously identified by chromosome banding techniques alone. However, the precise characterization of marker chromosomes is important for prenatal diagnosis and proper genetic counseling. In this study, we evaluated the chromosomal origin of marker chromosomes using a combination of banding cytogenetics and molecular cytogenetic techniques including diverse fluorescence in situ hybridization (FISH) assays and array comparative genomic hybridization (array CGH).ResultsIn a series of 2871 patients for whom cytogenetic analysis was requested, 14 cases with small supernumerary marker chromosomes (sSMCs) were identified. Nine sSMCs were mosaic, and five nonmosaic. Of the nine cases with known parental origins, four were identified as de novo, and four and one were maternally and paternally inherited, respectively. Six sSMCs were identified by FISH using centromeric probes; three sSMCs were derived from chromosome 15, including two heterochromatic sSMC(15)s and a large sSMC(15) spanning 15q11.1q13.1, and three sSMCs originated from chromosome 14 or 22. Array CGH revealed two cases with derivatives of chromosome 2 and whole chromosome painting multicolor-FISH (M-FISH) identified three cases with derivatives of chromosome 6, 16, and 19, respectively. One maker chromosome in Turner syndrome was characterized as sSMC(X) by preferential application of a centromeric probe for X-chromosome. In addition, one sSMC composed of genomic materials from chromosomes 12 and 18 was identified in parallel with parental karyotype analysis that revealed the reciprocal balanced translocation.ConclusionsThis report is the largest study on sSMCs in Korea and expands the spectrum of sSMCs that are molecularly characterized.Electronic supplementary materialThe online version of this article (doi:10.1186/s13039-016-0273-5) contains supplementary material, which is available to authorized users.

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Characterization of Small Supernumerary Marker Chromosomes By A Simple Molecular and Molecular Cytogenetics Approach

Cited by 2 publications

References 19 publications

Molecular characterization of supernumerary marker chromosomes found as unexpected chromosome abnormalities in nine prenatal and nine postnatal samples

Molecular characterization of supernumerary marker chromosomes found as unexpected chromosome abnormalities in nine prenatal and nine postnatal samples

Identification of small marker chromosomes using microarray comparative genomic hybridization and multicolor fluorescent in situ hybridization

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