To investigate whether the fission and fusion balance was altered in the PMD model, we measured levels of the main proteins involved in this process: dynamin related protein 1 (DRP1), fission protein 1 (Fis1), optic atrophy 1 protein (OPA1), mitofusin‐1 (MFN1) and mitofusin‐2 (MFN2), in the spinal cords of PLP‐tg66/66 mice. This evidence concerns the gene FIS1 and Pelizeaus-Merzbacher spectrum disorder.