Interestingly, pathway analyses of the top candidates emerging from the published genome-wide associations studies have revealed an enrichment in risk genes involved in neurite outgrowth and axon guidance66,67, rendering it tempting to speculate that abnormal guidance of dopaminergic projections during development is a common underlying cause of ADHD, and that lack of SorCS2 could play a role in this abnormality. Here, SORCS2 is linked to attention deficit-hyperactivity disorder.