HSAN-1B

2003

What Is HSAN-1B?

HSAN-1B is a type of CMT with an established locus but no confirmed causative gene identified to date.

For HSAN-1B, genetic evidence supports an autosomal dominant inheritance pattern, meaning that just one of the gene’s two copies needs a mutation to cause this subtype.

Clinical Features

The age of symptom onset in HSAN-1B is variable, ranging from childhood to adulthood. Symptoms typically begin in the lower extremities and progress over time to involve the upper limbs. Nerve conduction studies usually show somewhat slowed conduction velocities and reduced amplitudes, consistent with an axonal form of CMT.

HSAN-1B symptoms may include:

  • Weakness in the feet and lower legs
  • Muscle atrophy
  • Foot drop
  • Reduced or absent reflexes
  • Reduced sensation
  • A steppage-style walking pattern
  • Foot deformities, including high arches, and hammertoes (clawed toes)
  • Progressive involvement of the hands and forearms
  • Difficulty with fine motor skills and manual dexterity
  • Additional symptoms not listed here

Disease Course

HSAN-1B shows wide variability in severity and progression. Some individuals are mildly affected, while others develop a more severe disease. Disease progression is generally slow, and life expectancy is not reduced.

Clinical Basics

Subtype
HSAN-1B

Classification
HSAN

Neuropathy Type
Axonal

Inheritance Pattern
autosomal dominant

Genetic Context

HGNC-Approved Gene Symbol
Gene is Unknown at This Time

Chromosome
3p22-p24

Zygosity of Responsible Variant
Heterozygous

Variant Mechanism

Unknown

Details

Mechanistic basis:
Gene unknown

Confidence:
High

Prediction:
Chronic cough and gastroesophageal reflux accompanying dominant sensory loss give HSAN-1B a recognizable clinical signature, and linkage in the reported pedigree places the disease on chromosome 3p22-p24. No gene within that interval has been confirmed, and with no transcript and no segregating alleles to examine, the literature supplies no protein on which a mechanism could act.

Rationale:
The mapped interval carries many candidate transcripts and no confirmed one, so the evidence fixes a location and goes no further. The cough and reflux phenotype anchors the entity clinically and sets it apart from SPTLC1-related HSAN1A at 9q22, but a phenotype is not a substitute for an allele class.

HSAN-1B OMIM Entry

HSAN-1B OMIM

More Info

HSAN-1B Research Opportunity

CMT Natural History Study

Original Discovery Publication

Publication Title

A locus for hereditary sensory neuropathy with cough and gastroesophageal reflux on chromosome 3p22-p24

Authors

Kok, C., Kennerson, M. L., Spring, P. J., Ing, A. J., Pollard, J. D., & Nicholson, G. A.

Publication Date
September 1, 2003

DOI
10.1086/377591

Updated: July 18, 2026 | By: K. Raymond

The Dorsal Root

More From The Dorsal Root


A Name That Does Too Much Work

Jean-Martin Charcot's name appears throughout medicine, but nowhere does it create more confusion than in the foot. Learn why the CMT foot and Charcot neuroarthropathy, also known as Charcot foot, share a name yet differ in how they develop, appear, and are managed.


When Medicine Lost Its Compass

Evidence failed not because it was wrong, but because it was weaponized. I lived the downstream effects of that failure for more than a decade. This is what happens when medicine forgets that data always ends in a human being.


Error 404: Gene Not Found

CMT genetic testing often fails to identify the cause of the disease, even when comprehensive panels are used. Here, we discuss why this happens, what genetic tests can and cannot do, and why a negative result still matters.

© 2020–2026 Experts in CMT