Dysautonomia is any isease or malfunction of the autonomic nervous system. This includes postural orthostatic tachycardia syndrome (POTS), neurocardiogenic syncope, mitral valve prolapse dysautonomia, pure autonomic failure, autonomic instability and a number of lesser-known disorders. Other disorders, such as multiple system atrophy (Shy-Drager syndrome) and chronic fatigue syndrome, have dysautonomia as one of several system malfunctions.