HSAN
HSAN is the abbreviation for hereditary sensory and autonomic neuropathy. At the present time there are a number of different HSAN types.
All HSAN are characterized by widespread sensory dysfunction and variable autonomic dysfunction caused by incomplete development of sensory and autonomic neurons.
The disorders are genetically distinct from each other and caused by different gene mutations. However, genetic testing is not available for all HSAN disorders.
Some of the HSAN have more than one name, which can be confusing. It is important to determine which HSAN type the patient has so that we can provide accurate counseling regarding genetic testing, symptoms and treatments.
Below is a table listing the most common names, type of inheritance and gene location.
Nomenclature
|
Nomenclature
|
HSAN type*
|
Transmission
|
Chromosomal Location
|
Gene
|
|
Hereditary sensory radicular neuropathy
|
I
|
AD |
AD/ 9q22.1-22.3
|
SPTLC1
|
|
Congenital sensory neuropathy (CSN)
|
II
|
|
12p13.33 |
HSNW(?)
|
|
Familial dysautonomia (FD)/Riley Day
|
III
|
AR |
9q31 |
INBKAP
|
|
Congenital insensitivity to pain with anhidrosis (CIPA)
|
IV
|
AR |
1q21-22 |
NTRK1 (TKRA)
|
|
Congenital insensitivity to pain with partial anhidrosis
|
V
|
NK |
NK |
NTRK1
|
|
Congenital autonomic dysfunction with universal pain loss (CAD)
|
|
NK |
NK |
|
|
Progressive panneuropathy
|
|
NK |
NK |
|
AD: autosomal dominant, AR: autosomal recessive, NK: unknown
*HSAN nomenclature from Dyck P, Ohta M: Nueronal atrophy and degeneration predominantly affecting peripheral sensory neurons. In Peripheral Neuropathy Volume 2. Edited by: Dyck PJ, Thomas PK, Lambert EH. Philedelphia: WB Saunders; 1975: 791.
Although specific neuropathological features have been described for some of the disorders, obtainment of neurological tissue is invasive and not always feasible.
Thus clinical examination with careful assessment of sensory and autonomic function is preferable. Below is a table listing some of the clinical features for HSAN type II and HSAN type IV (CIPA).
Learn more about Familial Dysautonomia
Clinical Features |
HSAN type II |
HSAN type IV |
|
Onset
|
Birth
|
Birth
|
|
Initial symptoms (from birth to age 3 years)
|
Swallowing problems
|
Fevers
|
|
Self mutilation (65%)
|
Self mutilation (88%)
|
|
|
Delayed development
|
||
|
|
||
|
Unique Features
|
No axon flare
|
No axon flare
|
|
Lack of fungiform papilla
|
Anhydrosis
|
|
|
Hearing loss (30%)
|
Consanguinity (50%)
|
|
|
|
||
|
Sensory dysfunction
|
||
Depressed DTR |
Frequent (71%)
|
Infrequent (9%)
|
Pain perception |
Absent
|
Absent
|
Temperature perception |
Severe decrease
|
Absent
|
Vibration sense |
Normal
|
Normal to moderate Decrease
|
|
|
||
|
Autonomic
|
||
Gastroesophageal Reflux |
Frequent (71%)
|
Uncommon (24%)
|
Postural hypotension |
Uncommon (25%)
|
Uncommon (29%)
|
Episodic hypertension |
Rare
|
Rare
|
|
|
||
|
Ectodermal features
|
||
Dry skin |
No
|
Consistent
|
Fractures |
29%
|
71%
|
Scoliosis |
59%
|
23%
|
|
|
||
|
Intelligence
|
||
IQ<65 |
Common (38%)
|
Common (33%)
|
Hyperactivity |
Common (41%)
|
Common (54%)
|
Rare < 1%
Infrequent < 10%
Uncommon < 30%
Common 30-65%
Frequent > 65%
DTR = deep tendon reflexes
