Postural Orthostatic Tachycardia Syndrome Due to Net Deficiency, also known as familial orthostatic tachycardia due to norepinephrine transporter deficiency, is related to postural orthostatic tachycardia syndrome and orthostatic intolerance. An important gene associated with Postural Orthostatic Tachycardia Syndrome Due to Net Deficiency is SLC6A2 (Solute Carrier Family 6 Member 2).