Uniparentalism in sporadic colorectal cancer is independent of imprint status, and coordinate for chromosomes 14 and 18

Our previous allelotyping studies of 59 sporadic colorectal cancers revealed that loss of heterozygosity is most frequent for regions of chromosomes 14 and 18. Yet subsequent BAC microarray comparative genomic hybridization studies of the same tumor DNAs showed no corresponding pattern of copy number alteration for chromosome 14. To clarify this apparent discrepancy, we utilized hybridization to SNP microarrays; this revealed frequent uniparentalism for chromosome 14 and for chromosome 18. Based on the BAC array results combined with fluorescent in situ hybridization data, it was evident that uniparental disomy was occurring in many colorectal cancers as well as in additional chromosomes, and often coordinately involved chromosomes 14 and 18. Further studies examined the possibility that uniparentalism was directed towards the selection for imprinted genes, but no association with imprinting was observed.