HCN2 and breast cancer: In addition, we identified enhancer-related co-expressed lncRNA-mRNA relationship pairs as prognostic biomarkers for breast cancer subtypes, including one (OAZ1-AC027307.2) in Basal subtype, one (MUM1-AC012313.2) in LUMA subtype, one (PLK5-AC026471.4) in LUMB subtype, and one (HCN2-AC022431.1) in HER2 subtype.