What Is CMT2E?
CMT2E is a type of CMT caused by mutations in the NEFL gene. This gene provides instructions for making neurofilament light chain, a structural protein that helps maintain the normal structure and function of peripheral nerve axons. Mutations in the NEFL gene disrupt normal nerve structure, leading to impaired nerve signal transmission.
CMT2E is autosomal dominant, meaning that just one of the gene’s two copies needs a mutation to cause this subtype.
CMT2E is sometimes referred to as CMT1F/CMT2E and vice versa. This is because mutations in the NEFL gene cause both subtypes. When a nerve conduction study shows an axonal CMT, the diagnosis is CMT2E; when it shows a demyelinating CMT, the diagnosis is CMT1F.
Clinical Features
The first symptoms typically appear in the lower extremities, with onset usually occurring in infancy or childhood. In some individuals, early signs may include delayed motor development. Nerve conduction in CMT2E is typically normal or only mildly slowed, consistent with an axonal CMT.
CMT2E symptoms may include:
- First symptoms typically appear in the lower extremities
- Symptoms typically begin in infancy or childhood
- Delayed motor development
- Weakness in the feet and lower legs
- Muscle atrophy
- Reduced sensation
- Reduced or absent reflexes
- Foot deformities, including high arches and hammertoes (clawed toes)
- Loss of myelinated fibers
- Additional symptoms not listed here
Disease Course
CMT2E shows variability in severity and progression. Some individuals experience relatively mild symptoms, while others develop more pronounced weakness and functional limitations. Disease progression is generally slow, and life expectancy is not reduced.
