Additionally, lower concentrations of Cholecystokinin-8 (CCK-8) in CSF [99] and in peripheral lymphocytes [100] have been reported in PDA patients but not in healthy subjects, showing abnormalities in the entire CCK system (CCK-4 and CCK-8) and underpinning the pathophysiology of anxiety and panic disorder. The gene discussed is PTK7; the disease is panic disorder.