¶ Hereditary Sensory and Autonomic Neuropathy (HSAN)
Hereditary Sensory And Autonomic Neuropathy (Hsan) is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Hereditary Sensory and Autonomic Neuropathies (HSANs), also known as hereditary sensory neuropathies, are a group of rare genetic disorders characterized by progressive loss of sensory and autonomic nerve function. These disorders are caused by mutations in genes essential for the development, maintenance, and function of sensory and autonomic neurons.
HSANs are classified into multiple subtypes (HSAN Type I through Type VIII), each associated with different genetic causes, clinical presentations, and inheritance patterns. The disorders range from mild to severe, with some forms being degenerative and others remaining stable over time.
¶ Classification and Genetics
- Gene: SPTLC1 (HSAN1A), SPTLC2 (HSAN1B)
- Inheritance: Autosomal dominant
- Onset: Adolescence to early adulthood
- Features: Progressive loss of pain and temperature sensation, foot ulcers, amputations
- Gene: WNK1, NGF
- Inheritance: Autosomal recessive
- Onset: Early childhood
- Features: Severe sensory loss, autonomic dysfunction
- Gene: ELP1 (previously IKBKAP)
- Inheritance: Autosomal recessive
- Features: See Familial Dysautonomia page
- Gene: TRPV1 (formerly NTRK1)
- Inheritance: Autosomal recessive
- Features: Congenital insensitivity to pain, anhidrosis, intellectual disability
- Gene: NGF, SCN9A, SCN11A
- Inheritance: Autosomal recessive or dominant
- Features: Selective loss of pain perception
- Gene: SCN9A, SCN10A, SCN11A
- Inheritance: Autosomal recessive
- Features: Severe pain insensitivity, gastrointestinal issues
- Gene: SCN11A
- Inheritance: Autosomal dominant
- Features: Pain insensitivity, gastrointestinal dysmotility
- Gene: P2RX7
- Inheritance: Autosomal recessive
- Features: Developmental delay, pain insensitivity, argyria
Despite different genetic causes, HSANs share common pathological features:
- Sensory neuron degeneration: Progressive loss of dorsal root ganglion neurons
- Axonal dysfunction: Impaired axonal transport and maintenance
- Myelin abnormalities: Secondary demyelination in some forms
- Autonomic ganglion loss: Degeneration of autonomic nervous system neurons
- SPTLC1/2 mutations: Alter serine palmitoyltransferase activity, affecting lipid metabolism
- TRPV1 mutations: Impair pain and temperature sensing channels
- SCN9A/10A/11A mutations: Affect sodium channel function in pain signaling
- NGF mutations: Impair neurotrophic support for sensory neurons
- ELP1 mutations: Affect tRNA modification and transcriptional regulation
- Loss of pain perception: Most prominent feature
- Temperature insensitivity: Inability to feel hot or cold
- Touch perception loss: Often less affected than pain/temperature
- Proprioceptive deficits: Difficulty with position sense
- Orthostatic hypotension: Blood pressure dysregulation
- Gastrointestinal dysfunction: Dysphagia, gastroparesis
- Sweating abnormalities: Anhidrosis or hyperhidrosis
- Urinary dysfunction: Incontinence or retention
- Ulcerations: Painless injuries leading to chronic wounds
- Autoamputation: Loss of fingers/toes without pain
- Joint deformities: Charcot arthropathy
- Developmental delays: In some subtypes
- Cognitive impairment: In certain forms (HSAN4)
- Neurological examination: Assessment of sensory deficits
- Family history: Identification of inheritance pattern
- Autonomic testing: Cardiovascular reflex tests
- Nerve conduction studies: Shows sensory neuropathy
- Targeted gene panels: For known HSAN genes
- Whole exome sequencing: For atypical cases
- Specific mutation testing: For known family mutations
- Acquired sensory neuropathies
- Congenital insensitivity to pain
- Familial dysautonomia
- Multiple system atrophy
There is no cure for HSANs. Management focuses on:
- Pain management: For some forms with painful dysesthesia
- Wound care: Aggressive treatment of ulcers
- Physical therapy: Prevent contractures
- Orthopedic interventions: For deformities
- Blood pressure medications: For orthostatic hypotension
- Gastrointestinal motility agents: For dysmotility
- Bladder management: Catheterization if needed
- Regular monitoring: For ulcers, infections
- Protective footwear: Prevent injuries
- Temperature monitoring: Prevent burns
- Genetic counseling: For families
- Gene therapy: Experimental approaches for specific subtypes
- Small molecule therapies: Targeting specific molecular defects
- Cell therapy: Neural crest cell transplantation approaches
- Prevalence: Very rare (estimated 1 in 100,000 to 1 in 1,000,000)
- Inheritance: Varies by type (autosomal dominant or recessive)
- Ethnicity: Some forms more common in specific populations
- HSAN1A: More common in European populations
- HSAN4: More common in consanguineous families
- Understanding genotype-phenotype relationships: Why different mutations cause different phenotypes
- Development of biomarkers: For monitoring disease progression
- Gene therapy vectors: AAV and other viral approaches
- Pharmacological interventions: Targeting specific molecular pathways
- Patient registries: Natural history studies
Multiple mouse models exist for studying HSANs:
- Sptlc1 conditional knockout mice
- Trpv1 null mice
- Scn9a mutant mice
The study of Hereditary Sensory And Autonomic Neuropathy (Hsan) has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
Page created: 2026-03-01. Last updated: 2026-03-01.