TAC1 and neurodegenerative disease: Besides, four genes were clustered to play a protective role in neurodegenerative diseases, including two up-regulated genes, PRKACB and NTS, and two down-regulated genes, TAC1 and ACE. ID1, CHRNG, and S100B were the three genes that directly related to a predicted down-regulated nicotinic acetylcholine receptor that play important roles in the peripheral nervous system (Pillai et al., 2011).