Brain N-acetylaspartate is elevated in Pelizaeus-Merzbacher disease with PLP1 duplication

Area of Science:

• Neuroscience
• Biochemistry
• Genetics

Background:

• Pelizaeus-Merzbacher disease (PMD) is a rare, inherited neurological disorder.
• It is characterized by the underdevelopment or absence of myelin in the central nervous system.
• PLP1 gene duplications are a common cause of PMD.

Purpose of the Study:

• To investigate brain metabolite alterations in PMD patients with PLP1 duplications.
• To utilize quantitative proton magnetic resonance spectroscopy (MRS) for precise metabolite measurement.
• To explore the underlying disease mechanisms of PMD.

Main Methods:

• Quantitative proton MRS was performed on five male Japanese patients with PMD and PLP1 duplications.
• Localized spectra were acquired from the posterior centrum semiovale.
• Absolute metabolite concentrations were calculated using the LCModel.

Main Results:

• Patients with PMD showed significantly increased absolute concentrations of N-acetylaspartate (NAA) (+16%), creatine (Cr) (+43%), and myoinositol (MI) (+31%) compared to controls.
• No significant difference in choline concentration was observed.
• These findings were detected using absolute quantitation, unlike previous relative methods.

Conclusions:

• Elevated NAA suggests potential axonal involvement secondary to dysmyelination or an increased oligodendrocyte progenitor cell population.
• Increased Cr and MI concentrations may indicate reactive astrocytic gliosis.
• Absolute quantitation of brain metabolites is crucial for understanding the mechanisms of dysmyelinating disorders like PMD.