The hereditary demyelinating neuropathy Charcot-Marie-Tooth type 1A is caused by duplication or by point mutations of the PMP22 gene. Histopathological differences in these genotypes suggest distinct disease mechanisms. In the present investigation we demonstrate a pathologically altered cellular distribution of PMP22 in sural nerve biopsies of patients with PMP22 point mutations. In these patients, in contrast to findings in patients with PMP22 duplication, PMP22 partially accumulates in the Schwann cells instead of being inserted in the myelin sheath. These findings may explain the different histopathology and may suggest different mechanisms of pathogenesis in these genotypes.