This study seeks to systematically evaluate both microstructural (myelin content via MTR) and macrostructural features (nerve cross‐sectional area, or CSA, and shape) of the sciatic nerve within a cohort of patients with PMP22‐related diseases (CMT1A and HNPP) and healthy control subjects. The gene discussed is PMP22; the disease is hereditary neuropathy with liability to pressure palsies.