Compared to the expression in normal breast tissue samples, TNBC cases revealed a significantly reduced DKK3 expression (median fold change (FC): 12.7, P < 0.001), while expression loss was less abundant in carcinomas of the HER2-positive (median FC: 3.9) and luminal subtype (median FC: 2, Fig 1B). The gene discussed is ERBB2; the disease is carcinoma.