Familial dysautonomia (Riley-Day syndrome): when baroreceptor feedback fails.

Familial dysautonomia (FD) is a rare hereditary disorder caused by mutations within the gene that encodes for I-κ-B kinase complex associated protein (IKAP). A deficiency of IKAP affects the development of primary sensory neurons including those carrying baroreflex afferent volleys, a feature that explains their characteristic sensory loss and labile blood pressure. This review describes the history, the genotype of FD and the unusual cardiovascular autonomic phenotype of these patients. We outline the main consequences of a failure to receive information from arterial baroreceptors, including the characteristic "autonomic storms" and severe end-organ target damage.