2. CMT Type 2 (CMT2): The Axonal Type
CMT2, unlike CMT1, primarily affects the axons—the long projections of nerve cells—rather than the myelin sheath. The mutations in CMT2 are in genes responsible for the axonal function. When these axons are compromised, they can’t efficiently conduct signals, leading to muscle weakness and sensory loss, albeit at a typically slower progression than CMT1.
The symptoms of CMT2 often emerge during the second decade of life, although onset can range from infancy to middle age. The hallmark of CMT2 is muscle weakness, especially in the lower limbs. This weakness is often accompanied by muscle cramps, especially after exercise, and a reduced ability to feel pain or changes in temperature.
What sets CMT2 apart is its slower progression. Unlike CMT1, where the demyelination rapidly impacts nerve signal conduction, the axonal damage in CMT2 means the progression rate is comparatively reduced. This often offers patients more time to adjust and seek out effective interventions, though it doesn’t make the journey any less challenging. (2)
