By investigating the expression and clinical correlation of three clustered PCDH genes (including 15 PCDHA genes, 16 PCDHB genes and 22 PCDHG genes) in breast cancer, we demonstrated that PCDHGB7 was significantly decreased in TNBC tissues than in normal tissues and other subtypes of breast cancer (Figure 1A,C,D; Figure S1A,B,D) due to its high DNA methylation level (Figure S1E–M). This evidence concerns the gene PCDHGB7 and breast cancer.