Based on previous validation results from the same pathology laboratory, 7.4% of breast cancers with HER2 gene amplification in FISH analysis were false negative by 10H8-IHC (scored as 0 or 1+) and 9.7% of breast cancers without HER2 gene amplification in FISH analysis were false positive [18]. The gene discussed is ERBB2; the disease is breast carcinoma.