PSMA6 and postural orthostatic tachycardia syndrome: Furthermore, Gunning et al, in their study with 55 POTS patients enrolled, found that most POTS patients have at least 1 elevated G-protein coupled adrenergic receptor antibody (alpha-1 and alpha-2 adrenergic receptors and beta-1 and beta-2 adrenergic receptors), and in some cases, both adrenergic and muscarinic antibodies.