SLC6A2 and postural orthostatic tachycardia syndrome: Approximately 30%-60% of POTS patients fall under the category of hyperadrenergic type. An elevated standing plasma NE level of ≥600 pg/mL with an increased sympathetic tone manifesting as palpitations, tremors, hypertension, tachycardia, and anxiety is characteristic [23]. One case depicted the loss-of-function mutation of the SLC6A2 gene resulting in deficient NET and elevated mean supine HR [25]. Medications like TCAs, sympathomimetics (e.g., methylphenidate), and NE reuptake inhibitors (e.g., bupropion) are more frequently seen to cause NET block [23].