The Plp1 overexpressing mouse model (PLP-tg<sup>66/66</sup> ) develops a phenotype very similar to human PMD, with early and severe motor dysfunction and a dramatic decrease in lifespan.
Additionally, a single intracerebroventricular injection of MO-PLP into the brains of neonatal mice, carrying a deletion of an intronic splicing enhancer identified in a PMD patient that reduces the Plp1 spliced form, corrected alternative splicing at both RNA and protein levels in the CNS.
As only 10 - 30 % of patients with a Pelizaeus Merzbacher disease (PMD) phenotype carry mutations of the proteolipid protein (PLP) gene, we were interested if the degree and time-dependent progression of abnormal MRI and MRS findings would discriminate patients with mutations of the PLP gene (Pelizaeus Merzbacher disease, PMD) from patients without a defect of the PLP gene (Pelizaeus Merzbacher-like disease, PMLD).
Pelizaeus-Merzbacher disease (PMD) and a complicated form of familial spastic paraparesis (spastic paraplegia 2 [SPG2]) are X-linked development disorders of myelin formation caused by a mutation in the proteolipid protein (PLP) gene.Spastic paraplegia 2 is allelic to PMD.
Several naturally occurring and transgenic animal models with PLP gene mutations or deletions have contributed to our understanding of dysmyelination in PMD and the general knowledge of myelination and myelin repair.
A duplication of the whole PLP gene is the most common mutation and results usually in the milder classical phenotype, whereas point mutations in PLP gene often result in the rarer and more severe connatal form of PMD.
The fetus, in common with the proband, was identified as PMD-affected being a carrier of the PLP gene duplication, inherited from the mother, while the two aunts were non-carriers.
We conclude that the two cases are a rare type of dysmyelinating disorder with PMD phenotype of adult onset and could be caused by previously unrecognized abnormalities of the PLP gene or other genes.
Pelizaeus-Merzbacher disease (PMD) is an X-linked recessive disease caused by coding sequence mutations in the PLP gene, sub-microscopic duplications of variable sizes including the PLP gene or very rarely deletions of the PLP gene.
Different mutations in the same codon of the proteolipid protein gene, PLP, may help in correlating genotype with phenotype in Pelizaeus-Merzbacher disease/X-linked spastic paraplegia (PMD/SPG2).
Increased dosage of the proteolipid protein (Plp) gene causes CNS disease (Pelizaeus-Merzbacher disease [PMD]), which has many similarities to disorders of the PNS associated with duplication of the peripheral myelin protein-22 (PMP22) gene locus.
The myelin proteolipid protein (PLP) gene (i.e., the PLP/DM20 gene) has been of some interest because of its role in certain human demyelinating diseases, such as Pelizaeus-Merzbacher disease.
Pelizaeus-Merzbacher disease (PMD) is a dysmyelinating disorder of the central nervous system typically caused by duplications or missense mutations of the proteolipid protein (PLP) gene.
Duplications of the proteolipid protein (PLP) gene have been found in a proportion of patients, suggesting that, in addition to coding-region or splice-site mutations, overdosage of the gene can cause PMD.