Chromosome painting using FISH (fluorescence in situ hybridization) with chromosome-6-specific library demonstrates the origin of a de novo 6q+ marker chromosome

Abstract Background The presence of small supernumerary marker chromosomes (sSMCs) in a karyotype leads to diagnostic questions because the resulting extra material may cause abnormal development depending on the origin of the duplication/triplication. Because SMCs are so small, their origin cannot be determined by conventional cytogenetic techniques, and new molecular cytogenetic methods are necessary. Here, we applied a target approach to chromosome rearrangement analysis by isolating a chromosome of interest via microdissection and using it in fluorescence in situ hybridization (FISH) as a probe in combination with whole-chromosome painting probes. This approach allows to identify origins of both the euchromatin and repeat-rich regions of a marker. Case presentation We report a case of an adult male with congenital atresia of the rectum and anus, anotia, and atresia of the external auditory canal along with hearing loss. Karyotyping and FISH analysis with whole-chromosome painting probes of acrocentric chromosomes and the constructed microdissection library of the marker chromosome reliably identified an additional chromosome in some metaphases: mos 47,XY,+idic(22)(q11.2)[14]/46,XY [23]. Conclusion We propose to use whole-chromosome libraries and microdissected chromosomes in FISH to identify SMCs enriched with repeated sequences. We show that the methodology is successful in identifying the composition of a satellited marker chromosome.

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Recovery of a telomere-truncated chromosome via a compensating translocation in maize

Genome ◽

10.1139/g10-108 ◽

2011 ◽

Vol 54 (3) ◽

pp. 184-195 ◽

Cited By ~ 9

Author(s):

Robert T. Gaeta ◽

Tatiana V. Danilova ◽

Changzeng Zhao ◽

Rick E. Masonbrink ◽

Morgan E. McCaw ◽

...

Keyword(s):

In Situ Hybridization ◽

Fluorescent In Situ Hybridization ◽

Transgene Expression ◽

De Novo ◽

Extra Chromosome ◽

Single Gene ◽

B Chromosomes ◽

Chromosome 1 ◽

Chromosome 6

Maize-engineered minichromosomes are easily recovered from telomere-truncated B chromosomes but are rarely recovered from A chromosomes. B chromosomes lack known genes, and their truncation products are tolerated and transmitted during meiosis. In contrast, deficiency gametes resulting from truncated A chromosomes prevent their transmission. We report here a de novo compensating translocation that permitted recovery of a large truncation of chromosome 1 in maize. The truncation (trunc-1) and translocation with chromosome 6 (super-6) occurred during telomere-mediated truncation experiments and were characterized using single-gene fluorescent in situ hybridization (FISH) probes. The truncation contained a transgene signal near the end of the broken chromosome and transmitted together with the compensating translocation as a heterozygote to approximately 41%–55% of progeny. Transmission as an addition chromosome occurred in ~15% of progeny. Neither chromosome transmitted through pollen. Transgene expression (Bar) cosegregated with trunc-1 transcriptionally and phenotypically. Meiosis in T1 plants revealed eight bivalents and one tetravalent chain composed of chromosome 1, trunc-1, chromosome 6, and super-6 in diplotene and diakinesis. Our data suggest that de novo compensating translocations allow recovery of truncated A chromosomes by compensating deficiency in female gametes and by affecting chromosome pairing and segregation. The truncated chromosome can be maintained as an extra chromosome or together with the super-6 as a heterozygote.

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