Therefore, comprehensive results indicated that the mRNA expression of CLDN3, 4, 6, 7, 9, and 14 was upregulated in patients with BC compared with normal individuals, whereas that of CLDN2, 5, 8, 10, 11, 15, 19, and 20 was downregulated in patients with BC. The gene discussed is CLDN2; the disease is breast cancer.