What Is CMT2V?
CMT2V is a type of CMT caused by mutations in the NAGLU gene. This gene provides instructions for producing alpha-N-acetylglucosaminidase, an enzyme involved in the breakdown and recycling of complex sugars within lysosomes. Mutations in the NAGLU gene impair normal cellular recycling processes, leading to dysfunction of peripheral nerve axons and impaired nerve signal transmission.
CMT2V is autosomal dominant, meaning that just one of the gene’s two copies must have a CMT-causing mutation to cause this subtype.
Clinical Features
CMT2V is a late-onset subtype, with symptoms usually beginning in the forties, but they can begin sooner. 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.
CMT2V 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
CMT2V 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.
