Familial dysautonomia causes the autonomic and sensory nervous systems to malfunction, resulting in an incomplete development of the nerve fibers of these systems. The autonomic nervous system controls bodily functions such as the regulation of body temperature and blood pressure, swallowing and digestion, breathing in the absence of insufficient oxygen, safe stress responses, and overflow tears when one cries. The sensory nervous system regulates taste, perceptions of heat and cold, and pain reactions.
Children born with familial dysautonomia generally exhibit symptoms at a very young age, sometimes as young as 7 months. The most obvious symptom of familial dysautonomia is the lack of overflow tears that normally accompany emotional crying. Other telltale signs include a weak sucking reflex and poor muscle tone, misdirected swallowing, and blotchy skin. Older children with familial dysautonomia might exhibit symptoms such as: poor growth and failure to thrive; extensive sweating and/or drooling; puffy, reddish hands; blunted ability to detect pain or hot or cold temperatures; erratic blood pressure; delayed speech; impaired gait and curvature of the spine; smooth tongue; frequent lung infections; and dry eyes and corneal abrasions. Not all children with FD exhibit the same symptoms, and symptoms among children afflicted with FD will vary widely by severity and frequency.
