CMT2U is caused by autosomal dominant mutations in the MARS1 gene.
CMT2U is exceedingly rare and is considered a late adult-onset type of CMT. CMTers who have CMT2U can have symptoms start as late as their mid to late 60s. CMTers who have CMT2U will usually experience equal weakness, atrophy, and sensory loss in the upper and lower distal (points farthest away from the center of the body) and proximal (points closest to the center of the body) limbs. CMT2U disease progression is usually slow.