an inherited disorder occurring almost exclusively in Ashkenazic Jews (Ashkenazi) that is caused by abnormal functioning of the autonomic nervous system. Riley-Day syndrome is characterized by emotional instability, decreased tear production, low blood pressure upon standing up (postural hypotension), excessive sweating and blotchiness of the skin during excitement and eating, difficulty in swallowing, insensitivity to pain, seizures, vomiting, breath-holding, and poor motor coordination. Infants with Riley-Day syndrome often develop pneumonia caused by inhalation of formula or breast milk. There is no cure for the disorder; most patients die in childhood.