ROMA: Representational oligonucleotide microarray analysis. A method for the detection of genomic aberrations between any two samples of DNA. ROMA measures the relative concentration of DNA in the two samples by hybridizing differentially labeled samples to a set of probes. By arraying oligonucleotide probes designed from the human genome sequence, and hybridizing with "representations" from the two genomes, regions of the genome with altered "copy number" can be detected. ROMA has permitted the identification of variation between cancer and normal genomes, as well as between normal human genomes.
Large-scale variations have been found in the normal genome from one person to the next. These large variations are termed copy number polymorphisms (CNPs). They are common and are widely distributed in the human genome. In an analysis of 20 individuals from different geographic backgrounds, this type of large genomic variation occurred at least once in every 70 genes. ROMA has revealed that there is considerable variation in the human genome, most of which was not even suspected by other methods of genomic analysis.