CMT2DD is caused by autosomal dominant mutations in the ATP1A1 gene. CMT2DD predominately affects the lower limbs.
CMT2DD symptoms can start to occur anywhere between early childhood and late adulthood. CMTers who have CMT2DD tend to have a more severe disease course when symptoms star to occur in early childhood. However, symptoms, progression, and severity can be widely variable, and even within the same family.
CMTers who have CMT2DD usually experience lower leg/ankle/foot weakness and atrophy that leads to pes cavus (high arches) hammer toes, and ankle instability. A CMTer who has CMT2DD will usually experience weakness and atrophy of the intrinsic hand muscles, leading to loss of dexterity, grip strength and contractures (clawed hands). Sensory loss can be highly variable.