Since ATP induces an astrocytic neurotoxic phenotype through P2X7 receptor signaling (Gandelman et al., 2010), one can hypothesize that increased extracellular ATP in ALS, whether exacerbated by motoneurons and/or microglia contributes to the pathogenic microgliosis. This evidence concerns the gene P2RX7 and amyotrophic lateral sclerosis.