[Riley-Day syndrome (familial dysautonomia)].

Riley-Day syndrome (RDS, familial dysautonomia) is reviewed from a viewpoint of autonomic disturbance. RDS shows pandysautonomia, including alacrima, orthostatic hypotension, gastrointestinal paresis, and paroxysmal hyperautonomic state, such as hypertension, vomiting crisis, and blotchy erythema. Sensory disturbances, including absence of taste and pain sensation, are common. Fungiform papillae on the tongue are sparse. Tests of autonomic function reveal postganglionic dysfunction. Sural nerve biopsy reveals depletion of small myelinated fibers and unmyelinated fibers, which corresponds well with the sensory and autonomic disturbances. As to the pathogenesis of RDS, dysgenesis of neurons from the neural crest or abnormality of nerve growth factor has been suggested, but this remains undetermined.