AGTR1 and postural orthostatic tachycardia syndrome: Clustering of different GPCR-AAbs seems to be present in several disorders: Patients with POTS showed seropositivities of β1-fAAb, β2-fAAb, α1-fAAb, M2-fAAb, and AT1-fAAb [44,46,47,48]; distinct patterns including β2-fAAb and M2-fAAb were observed in Chagas cardiomyopathy, electrical cardiac abnormalities, complex regional pain syndrome and fatigue syndrome [35,49,50,51].