Selective cerebral volume reduction in Rett syndrome: a multiple-approach MR imaging study

Area of Science:

• Neuroscience
• Genetics
• Medical Imaging

Background:

• Rett syndrome (RTT) is a neurodevelopmental disorder.
• Previous studies noted volumetric abnormalities but predated MECP2 gene identification.
• MECP2 mutations are found in most RTT cases.

Purpose of the Study:

• Characterize regional brain volume changes in MECP2-mutated RTT.
• Correlate neuroanatomy with clinical severity in RTT.
• Investigate specific brain regions affected in RTT.

Main Methods:

• Utilized MR imaging (spoiled gradient-recalled acquisition).
• Employed complementary semiautomated Talairach- and voxel-based approaches.
• Analyzed 23 girls with MECP2 mutations/RTT and 25 controls, including discordant twins.

Main Results:

• Observed absolute volumetric reductions throughout the brain in RTT.
• Found selective gray matter decreases in the dorsal parietal lobe and white matter reductions.
• More severe RTT phenotypes correlated with greater anterior frontal lobe volume reduction.

Conclusions:

• Selective dorsal parietal gray matter reduction and occipital cortex preservation are key RTT neuroanatomic features.
• Anterior frontal lobe reduction correlates with RTT clinical severity.
• Affected regions may underlie RTT's core functional deficits.