What Is CMT2X?
CMT2X is a type of CMT caused by mutations in the SPG11 gene. This gene provides instructions for producing spatacsin, a protein involved in intracellular trafficking and maintenance of long axons in nerve cells. Mutations in the SPG11 disrupt normal axonal maintenance and transport, leading to degeneration of peripheral nerve axons and impaired nerve signal transmission
CMT2X is autosomal recessive, meaning both copies of the gene need a mutation to cause this subtype.
Clinical Features
The age of symptom onset in CMT2X is variable, ranging from early childhood to adulthood. Symptoms typically begin in the lower extremities and progress over time to involve the upper limbs. An earlier onset isn’t necessarily associated with a more severe disease course. Nerve conduction studies usually show somewhat slowed conduction velocities and reduced amplitudes, consistent with an axonal form of CMT. CMT2X should not be confused with CMTX2. CMTX2 is a separate X-linked CMT subtype.
CMT2X symptoms may include:
- Weakness in the feet and lower legs
- Muscle atrophy
- Foot drop
- A steppage-style walking pattern
- Reduced sensation
- Reduced or absent reflexes
- Foot deformities, including high arches and hammertoes (clawed toes)
- Progressive involvement of the hands and forearms
- Difficulty with fine motor skills and manual dexterity
- Balance difficulties
- Additional symptoms not listed here
Disease Course
CMT2X 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.
