Incomplete penetrance could be attributed to the unique presentation, which was unmasked only by vincristine administration.12 In spite of the standard dosing, aggressive neurotoxic symptom development within a period of days could suggest an increased sensitivity to vincristine in a preexisting CMT1A disease.13 A late-onset CMT disease were reported previously with early growth response 2 (EGR2), myelin protein zero (MPZ) mutations of other CMT types but never reported in the PMP22 gene.14 Vincristine suppresses the microtubules during cell cycle, blocking the metaphase stage of mitosis. This evidence concerns the gene MPZ and Charcot-Marie-Tooth disease.