RecruitingA Prospective Natural History and Outcome Measure Discovery Study of Charcot-Marie-Tooth Disease, Type 4JThis is a multicenter, longitudinal, prospective observational natural history study of subjects with a molecularly confirmed diagnosis of CMT4J. The study will enroll 20 subjects of any age into a uniform protocol for follow-up and evaluations. Subject visits will occur every 12 months + 4 weeks for up to 2 years.