Claudin-5 is a major TJ protein that forms the backbone of the BBB’s paracellular barrier.25–27 Claudin-5 creates TJ strands that seal the inter-endothelial spaces, preventing the passage of solutes and larger molecules between adjacent BECs.26,28 It is also involved in regulating the size and charge selectivity of molecules that can cross the BBB.26 Genetic deletion of the Cldn5 gene disrupts the BBB of both newborn and adult mice, resulting in neuroinflammation, seizures, cognitive decline, and lethality.26,29. The gene discussed is CLDN5; the disease is Mental deterioration.