Pelizaeus-Merzbacher disease (PMD; MIM#312080) is a rare X-linked leukodystrophy presenting with motor developmental delay associated with spasticity and nystagmus.
The common manifestations of the disease in patients with PLP1 mutations or duplications in this study were nystagmus in early infancy, dysmyelination revealed by magnetic resonance imaging (MRI), and auditory brain response abnormalities.
A patient who developed nystagmus at 16 months and progressive spastic ataxia at 18 months was found to have a 19-base pair (bp) deletion of a G-rich region near the 5' end of intron 3 of the PLP gene.