Sequencing of an additional five primary HER2-positive breast cancers and corresponding six brain metastases was performed to median depths of 447× (range: 84×–645×), 392× (range: 139×–1,148×) and 467× (range: 196×–1,790×) in the primary tumors, brain metastases and matched normal counterparts, respectively (Table 1, Supplementary Table 2). The gene discussed is ERBB2; the disease is breast carcinoma.