K+–Cl− co-transporter (KCC2) and Na+–K+–2Cl− co-transporter (NKCC1) are the main regulators of neuronal intracellular chloride concentration; altered expression patterns of KCC2 and NKCC1 have been reported in several neurodegenerative diseases. This evidence concerns the gene SLC12A5 and neurodegenerative disease.