Fig 2. Concordance of Talairach and voxel-based findings in the prefrontal GM in more severe versus less severe RTT subjects. Girls with less severe clinical presentation, according to gait abnormality criterion, showed relative preservation of prefrontal GM volumes, corresponding roughly with Brodmann areas 10/46. A, Top left depicts Talairach-derived data, whereas bottom left shows VBM-derived data. B, Boxplots (percentiles) of Talairach-based prefrontal GM volumes illustrate that girls with less severe clinical presentation show volumes intermediate between control subjects and those with more severe phenotype.