GJA1 and neurodegenerative disease: Upregulated A/A GJ connectivity mediated by the overexpression of Cx43 GJs upon astrogliosis in neurodegenerative diseases has been linked to neuronal excitotoxicity via excessive calcium signaling and diminished homotypic Cx43–Cx43 GJ coupling, which leads to the overactivation of Cx43 hemichannels [57].