However, presynaptic binding partners of NGL-3 such as PTPδ and PTPσ have been implicated in multiple brain disorders, including restless leg syndrome, attention deficit/hyperactivity disorder, autism spectrum disorder, bipolar disorder, Alzheimer disease, obsessive compulsive disorder, addiction, and mood liability [1, 4, 95]. This evidence concerns the gene PTPRD and early-onset autosomal dominant Alzheimer disease.