A mitotic recombination map proximal to the APC locus on chromosome 5q and assessment of influences on colorectal cancer risk.
BMC Med Genet
; 10: 54, 2009 Jun 10.
Article
em En
| MEDLINE
| ID: mdl-19515250
ABSTRACT
BACKGROUND:
Mitotic recombination is important for inactivating tumour suppressor genes by copy-neutral loss of heterozygosity (LOH). Although meiotic recombination maps are plentiful, little is known about mitotic recombination. The APC gene (chr5q21) is mutated in most colorectal tumours and its usual mode of LOH is mitotic recombination.METHODS:
We mapped mitotic recombination boundaries ("breakpoints") between the centromere (~50 Mb) and APC (~112 Mb) in early colorectal tumours.RESULTS:
Breakpoints were non-random, with the highest frequency between 65 Mb and 75 Mb, close to a low copy number repeat region (68-71 Mb). There were, surprisingly, few breakpoints close to APC, contrary to expectations were there constraints on tumorigenesis caused by uncovering recessive lethal alleles or if mitotic recombination were mechanistically favoured by a longer residual chromosome arm. The locations of mitotic and meiotic recombination breakpoints were correlated, suggesting that the two types of recombination are influenced by similar processes, whether mutational or selective in origin. Breakpoints were also associated with higher local G+C content. The recombination and gain/deletion breakpoint maps on 5q were not, however, associated, perhaps owing to selective constraints on APC dosage in early colorectal tumours. Since polymorphisms within the region of frequent mitotic recombination on 5q might influence the frequency of LOH, we tested the 68-71 Mb low copy number repeat and nearby tagSNPs, but no associations with colorectal cancer risk were found.CONCLUSION:
LOH on 5q is non-random, but local factors do not greatly influence the rate of LOH at APC or explain inter differential susceptibility to colorectal tumours.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Recombinação Genética
/
Cromossomos Humanos Par 5
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Neoplasias Colorretais
/
Genes APC
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Perda de Heterozigosidade
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Mitose
Tipo de estudo:
Etiology_studies
/
Risk_factors_studies
Limite:
Humans
Idioma:
En
Ano de publicação:
2009
Tipo de documento:
Article