title: Massively parallel sequencing reveals the complex structure of an irradiated human chromosome on a mouse background in the Tc1 model of Down syndrome.
abstract: Down syndrome (DS) is caused by trisomy of chromosome 21 (Hsa21) and presents a complex phenotype that arises from abnormal dosage of genes on this chromosome. However, the individual dosage-sensitive genes underlying each phenotype remain largely unknown. To help dissect genotype--phenotype correlations in this complex syndrome, the first fully transchromosomic mouse model, the Tc1 mouse, which carries a copy of human chromosome 21 was produced in 2005. The Tc1 strain is trisomic for the majority of genes that cause phenotypes associated with DS, and this freely available mouse strain has become used widely to study DS, the effects of gene dosage abnormalities, and the effect on the basic biology of cells when a mouse carries a freely segregating human chromosome. Tc1 mice were created by a process that included irradiation microcell-mediated chromosome transfer of Hsa21 into recipient mouse embryonic stem cells. Here, the combination of next generation sequencing, array-CGH and fluorescence in situ hybridization technologies has enabled us to identify unsuspected rearrangements of Hsa21 in this mouse model; revealing one deletion, six duplications and more than 25 de novo structural rearrangements. Our study is not only essential for informing functional studies of the Tc1 mouse but also (1) presents for the first time a detailed sequence analysis of the effects of gamma radiation on an entire human chromosome, which gives some mechanistic insight into the effects of radiation damage on DNA, and (2) overcomes specific technical difficulties of assaying a human chromosome on a mouse background where highly conserved sequences may confound the analysis. Sequence data generated in this study is deposited in the ENA database, Study Accession number: ERP000439.
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom. smg@sanger.ac.uk
authors.forename: Susan M
authors.initials: SM
authors.lastname: Gribble
authors.forename: Frances K
authors.initials: FK
authors.lastname: Wiseman
authors.forename: Stephen
authors.initials: S
authors.lastname: Clayton
authors.forename: Elena
authors.initials: E
authors.lastname: Prigmore
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Langley
authors.forename: Fengtang
authors.initials: F
authors.lastname: Yang
authors.forename: Sean
authors.initials: S
authors.lastname: Maguire
authors.forename: Beiyuan
authors.initials: B
authors.lastname: Fu
authors.forename: Diana
authors.initials: D
authors.lastname: Rajan
authors.forename: Olivia
authors.initials: O
authors.lastname: Sheppard
authors.forename: Carol
authors.initials: C
authors.lastname: Scott
authors.forename: Heidi
authors.initials: H
authors.lastname: Hauser
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Stephens
authors.forename: Lucy A
authors.initials: LA
authors.lastname: Stebbings
authors.forename: Bee Ling
authors.initials: BL
authors.lastname: Ng
authors.forename: Tomas
authors.initials: T
authors.lastname: Fitzgerald
authors.forename: Michael A
authors.initials: MA
authors.lastname: Quail
authors.forename: Ruby
authors.initials: R
authors.lastname: Banerjee
authors.forename: Kai
authors.initials: K
authors.lastname: Rothkamm
authors.forename: Victor L J
authors.initials: VL
authors.lastname: Tybulewicz
authors.forename: Elizabeth M C
authors.initials: EM
authors.lastname: Fisher
authors.forename: Nigel P
authors.initials: NP
authors.lastname: Carter
mesh_terms: D000818:Animals; D002877:Chromosomes, Human / Q000528:radiation effects; D002891:Chromosomes, Human, Pair 21; D055028:Comparative Genomic Hybridization; D004195:Disease Models, Animal; D004314:Down Syndrome / Q000235:genetics*; D005720:Gamma Rays / Q000009:adverse effects; D018628:Gene Dosage; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D011995:Recombination, Genetic; D014314:Trisomy