PMP22 (Point Mutation)
CMT1E is caused by autosomal dominant mutations in the PMP22 gene. Where CMT1A is caused by a duplication of this same gene, CMT1E is caused by point mutations within the gene. A point mutation is a mutation within the gene rather than the gene being duplicated or deleted.
CMT1E symptom onset usually occurs by the time the CMTer is 2 years old, and CMT1E tends to be more severe than CMT1A. Many CMTers with 1E progress to needing mobility aids such as walkers and wheelchairs far sooner than their 1A counterparts.