Analysis of copy number changes suggests chromosomal instability in a minority of large colorectal adenomas

Abstract

We have examined chromosomal-scale mutations in 34 large colorectal adenomas (CRAs). A small number of changes (median = 2, IQR = 0-4) were found by array-comparative genomic hybridization (aCGH) in most tumours. The most common changes were deletions of chromosomes 1p, 9q, 17, 19, and 22, and gains of chromosomes 13 and 21. SNP-LOH analysis and pseudo-digital SNP-PCR analysis detected occasional copy-neutral LOH. Some aCGH changes found frequently in colorectal carcinomas, such as deletions of chromosomes 4q and 18q, were very infrequent in the adenomas. Almost all copy number changes were of small magnitude, far below the predicted levels even for single copy gain/loss; investigation sugge..