PLP1 and Pelizeaus-Merzbacher spectrum disorder: Furthermore, the intra-axonal mitochondrial density is significantly increased in demyelinated axons of plp1-overexpressing mice, demonstrating profound energy uncoupling with attempts at compensation by the neuron in this model of the Pelizaeus-Merzbacher disease, a human inherited leukodystrophy that exhibit hypomyelination and subsequent neurodegeneration [63].