Other hereditary neuropathies

There are a number of rare inherited diseases with prominent peripheral nerve involvement. They include porphyria, leukodystrophies, Krabbe’s disease, Fabry disease, hereditary amyloidosis, giant axonal neuropathy, and Tangier disease. Although uncommon, each disorder has distinctive features, and familiarity with them aids in their recognition. Porphyria typically presents in an acute fashion, leukodystrophies include upper motor neuron findings (spasticity, exaggerated deep tendon reflexes) and some are associated with a demyelinating polyneuropathy with slowed nerve conduction velocity, whereas Fabry disease and hereditary amyloidosis preferentially affect small caliber unmyelinated sensory and autonomic nerves resulting in prominent pain and autonomic dysfunction. Systemic symptoms or signs of involvement of other organ systems often provide diagnostic clues. Abdominal pain and psychosis are common in porphyria, characteristic skin lesions occur in Fabry disease, and heart and renal failure suggests amyloidosis. Diagnostic conformation is aided by nerve biopsy, biochemical enzymatic assay, or genetic testing.