The ERBB2 (17q12) Red + Copy Control 17 Green FISH probe is designed to detect the amplification of the ERBB2 (HER2) gene. The ERBB2 gene is located on chromosome 17 and encodes a tyrosine kinase epidermal growth factor receptor1. Approximately 20% of breast cancers harbor ERBB2 overexpression and/or gene amplification1. The amplification of the ERBB2 gene is considered a common prognostic marker in breast cancer and is associated with an aggressive phenotype2. Fluorescence in situ hybridization (FISH) is one of the approved diagnostic techniques utilized to distinguish ERBB2 gene amplification1.