Tan et al. [48] performed a bioinformatics analysis using the TCGA-BRCA and METABRIC databases to explore the influence of ErbB2 CNVs on ErbB2 mRNA expression and found that elevated mRNA levels corresponded to higher CNV scores in HER2-low breast cancer, with a positive but weak correlation between HER2 IHC scores and CNV scores. This evidence concerns the gene ERBB2 and breast cancer.