In epithelial cancers, copy number alterations have been shown to be drivers of the cancer phenotype through amplification and over expression of oncogenes like ERBB2 and loss of tumour suppressors such as CDKN2A. Ovarian cancer is both heterogeneous and cytogenetically complex making it difficult to decipher the key genomic regions affected by CNA. The gene discussed is ERBB2; the disease is cancer.