P2RX7 and early-onset autosomal dominant Alzheimer disease: Release of ATP and other nucleotides seems to modulate microglial responses via P2Y and P2X receptors, with the P2X7 subtype standing out for its known pro-inflammatory activity and for its up-regulation in both a transgenic mouse model of Alzheimer’s disease and in the brains from Alzheimer’s disease patients (Parvathenani et al., 2003; McLarnon et al., 2006).