Topological Analysis of Amplicon Structure in Comparative Genomic Hybridization CGH Data: An Application to ERBB2/HER2/NEU Amplified Tumors

DNA copy number aberrations CNAs play an important role in cancer and can be experimentally detected using microarray comparative genomic hybridization CGH techniques. Amplicons, CNAs that extend over large sections of the genome, are difficult to study since they may contain multiple independent and dependent copy number changes. Here, we propose an algorithm to find the CNAs structure within a given amplicon. Our method relies on the observation that co-occurring CNAs can be encoded as 1-dimensional cycles. Applying this method to breast cancer patients known as ERBB2/HER2/NEU amplified we find three regions that can be co-occuring: the first region is in the cytoband 17q12, where the ERBB2 gene is located, the second region expands between 17q21.2 to 17q21.31 and includes the keratin genes, the third one is 17q21.33. We suggest that the first homology group helps uncovering the structure of amplicons.