PLP1 and Spastic paraplegia type 2: Mutations in the PLP1 gene are responsible for a wide range of X-linked white matter disorders, collectively termed PLP1-related disorders, which together represent a continuum of neurological features, that characterize conditions ranging from Pelizaeus-Merzbacher disease (PMD, MIM# 312080) with severe CNS involvement to the milder spastic paraplegia type 2 (SPG2, MIM# 312920) [1-3].