ERBB2 and breast cancer: In the external validation series, out of the 10 BC with 4.0–5.9 HER2 s/n by FISH, 2 presented a disomic pattern of which, through MLPA, 1 (50%) was amplified (mean value ≥1.5) and 1 (50%) showed a gain (mean value ≥1.3 but <1.5).