However, CLDN1 shows marked downregulation in pheochromocytoma and paraganglioma (PCPG) (log2FC = -4.7), and CLDN2 exhibits even more pronounced downregulation in sarcoma (SARC) (log2FC = -10.2). The gene discussed is CLDN2; the disease is hereditary pheochromocytoma-paraganglioma.