AK1 and Huntington disease: Genes involved in purine metabolism (Entpd2, Ampd3, Pnp, and Xdh), adenosine metabolism (Ada), conversion of adenine nucleotides (adenylate kinase 1 [Ak1] and inosine monophosphatase dehydrogenase 2 [Impdh2]), and equilibrative nucleoside transporter-like ENT1 and ENT2 were altered in cardiac tissue, striatum, and skeletal muscle of R6/2 mice of HD (Toczek et al., 2016a; Kao et al., 2017; Mielcarek et al., 2017).