Magnetic resonance imaging of a unique mutation in a family with Pelizaeus-Merzbacher disease.

Pelizaeus-Merzbacher disease (PMD) is a rare dysmyelination disorder, characterized by significant developmental delay, truncal hypotonia, spasticity, dysarthria, and nystagmus. Conventional magnetic resonance (MR) images demonstrate discordance of myelin maturation, while newer MR techniques, such as MR spectroscopy and diffusion tensor imaging, may be helpful in disease assessment. We report on a family of two young boys and their mother who share the same unusual 4-bp deletion of the PLP1 gene: c51_54 del TTCC, causing truncation of the PLP1 in exon 2. The brain MRI appearances in this unique deletion, using newer MR imaging, are described.