CPT1, CPT2, and the carnitine transporter SLC22A5/OCTN2 are expressed in several regions of rat brain; in addition, a deletion in the OCTN2 gene has been associated with attention-deficit/hyperactivity disorder [32], and mutations in the HTML gene were considered to be a risk factor in autism [34]. This evidence concerns the gene CPT2 and attention deficit-hyperactivity disorder.