Similarly, astrocytes open their Cx43 hemichannels in Parkinson’s disease (Rufer et al., 1996; Kawasaki et al., 2009) Alzheimer’s disease (Orellana et al., 2011b; Takeuchi et al., 2011; Yi et al., 2016) and ischemia (Contreras et al., 2002; Retamal et al., 2006). Here, GJA1 is linked to early-onset autosomal dominant Alzheimer disease.