PMP22 and Charcot-Marie-Tooth disease: Of the patients with demyelinating CMT, 76% (57/75) carried a genetic mutation, with the most frequent genetic causes being PMP22 duplication (44%, 33/75), PMP22 point mutation (10.7%, 8/75) and GDAP1 mutation (5.3%, 4/75), accounting for 60% of all demyelinating CMT patients with an identified mutation.