Clinical Information

The hereditary sensory and autotomic neuropathies (HSAN), or hereditary sensory neuropathies (HSN) if autonomic dysfunction is absent, are one of the major categories of inherited peripheral neuropathies. They predominantly feature slowly progressive loss of multimodal sensation and autonomic dysfunction. The HSAN have a range of phenotypes from pure sensory involvement through phenotypes with levels of motor involvement and minor autonomic disturbances, to almost pure autonomic neuropathies. The most common features of HSAN include the loss of sensation of pain and temperature.

HSAN are subdivided into types 1 through 5 based on age of onset, inheritance pattern, and clinical features. HSAN type 1 follows an autosomal dominant inheritance pattern with juvenile through adult onset. Clinically this group is variable but can include severe sensory loss and autonomic dysfunction. HSAN type 2 follows an autosomal recessive inheritance pattern with onset in infancy or early childhood. This group is predominantly a sensory neuropathy with distal numbness and progressive loss of pain, temperature, and touch sensation. Motor involvement is not common in patients with HSAN type II. HSAN type 3 is also called familial dysautonomia and has autosomal recessive inheritance. Patients present with prominent, widespread autonomic disturbances, as well as small-fiber sensory dysfunction. HSAN type 4 is also called congenital insensitivity to pain with anhidrosis and has autosomal recessive inheritance. HSAN type 5 strongly resembles HSAN type 4, but patients show hypohidrosis instead of anhidrosis and do not have intellectual disability.