In this work, we validated the new Metafer 4 classifier in 64 breast cancer specimens (32 nonamplified and 32 amplified cases), chosen randomly among eligible clearly nonamplified and amplified cases of our cohort, as required from the ASCO/CAP and the Canadian guidelines for HER2 testing in breast cancer for validation of a new test. The gene discussed is ERBB2; the disease is breast cancer.