What Is HSN w/SPG?
HSN w/SPG is a type of CMT caused by autosomal recessive mutations in the CCT5 gene. This gene provides instructions for making a component of a protein-folding complex that helps other proteins achieve their correct shape within nerve cells. Mutations in the CCT5 gene disrupt this function, leading to impaired nerve signal transmission.
HSN w/SPG is autosomal recessive, meaning that both copies of the gene must have a mutation to cause this subtype.
Clinical Features
Symptoms of HSN w/SPG combine a sensory neuropathy with spastic paraplegia, meaning that sensory loss occurs alongside stiffness and weakness of the legs from involvement of the upper motor neurons. Nerve conduction studies reflect a sensory and axonal process.
HSN w/SPG symptoms may include:
- Reduced sensation in the feet and lower legs
- Leg stiffness and spasticity
- Progressive weakness of the lower limbs
- A spastic gait
- Painless injuries from reduced sensation
- Foot drop
- Additional symptoms not listed here
Disease Course
HSN w/SPG 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.
