ADRB2 and postural orthostatic tachycardia syndrome: Later, in 2014, Li et al. documented specific antibodies against receptors in the autonomic nervous system in POTS patients, specifically autoantibodies against adrenergic alpha-1 receptors (ADRA1) and autoantibodies against beta-1 (ADRB1) and beta-2 adrenergic receptors (ADRB2) [10].