Adenosine 2A receptors (A2A) are G-protein-coupled receptors targeted by CNS neurotransmitters and highly implicated in multiple neurological disorders [268], such as schizophrenia, bipolar disorder, HD, PD, preclinical models of AD, addiction, aging, epilepsy, and multiple sclerosis [269,270]. This evidence concerns the gene IGKV2D-29 and Huntington disease.