We then performed unsupervised expression cluster analysis on the DCIS samples, which resulted in groups that were enriched in specific PAM50 subtypes (Supplemental Figures S4A, S5A), with Expression Cluster 1 highly enriched for HER2 and Basal tumors, while Expression Cluster 2 consisted mostly of luminal tumors. The gene discussed is ERBB2; the disease is ductal breast carcinoma in situ.