PLP1 and Spastic paraplegia type 2: In contrast to the Plp1 overexpressing mouse, the rumpshaker mouse (point mutation in the Plp1 gene; Ile186Thr), a model of the allelic disorder spastic paraplegia type 2, has only a mild neuroinflammatory response characterized by a slight increase in microglial abundance in white matter tracts where myelin is thinner than normal, but otherwise grossly normal in appearance.