The evaluation of autonomic nervous function in a patient with hereditary sensory and autonomic neuropathy type IV with novel mutations of the TRKA gene.

We report on a 10-year-old girl with anhidrosis and insensibility to pain, but no severe mental retardation or self-mutilation, diagnosed as hereditary sensory and autonomic neuropathy type IV (HSAN IV). Genetic analysis of her TRKA gene, which is responsible for HSAN IV, revealed two novel missense mutations in the tyrosine kinase domain. Cardiovascular autonomic nervous system function tests showed normal muscle sympathetic nerve activity associated with arterial baroreflex, reduced skin sympathetic nerve activity in the second and fifth fingers and palms, and abnormal circadian rhythm of cardiovascular autonomic nervous system. These findings have never before been reported in HSAN IV and may provide a clue to the neurological pathophysiology of this disease.