Nerve growth factor (NGF-beta) is important for the development and maintenance of the sympathetic and sensory nervous systems. NGF-beta stimulates division and differentiation of sympathetic and embryonic sensory neurons. Defects in NGF-beta are the cause of hereditary sensory and autonomic neuropathy type 5 (HSAN5). The hereditary sensory and autonomic neuropathies are a genetically and clinically heterogeneous group of disorders characterized by degeneration of dorsal root and autonomic ganglion cells, and by sensory and/or autonomic abnormalities.