Selective Cerebral Volume Reduction in Rett Syndrome: A Multiple-Approach MR Imaging Study

Abstract

BACKGROUND AND PURPOSE:Previous studies have examined volumetric abnormalities in Rett syndrome (RTT), using MR imaging and focusing on selective changes. However, these studies preceded the identification of MECP2 as the gene mutated in most RTT cases. We studied regional brain volume changes as noted by MR imaging in girls with RTT who had mutations in the MECP2 gene and more or less severe clinical outcomes to further characterize the neuroanatomy of RTT and its correlations with clinical severity.

Behavioral and Neuroanatomical Phenotypes in Mouse Models of Autism

“…Brain metabolism was examined with magnetic resonance spectroscopy, detecting several metabolic differences in the Mecp2 KO mice. This overall reduction in brain size is a common finding in the human Rett syndrome phenotype; similarly, the decreased thickness of the corpus callosum and motor cortex are also commonly found in human Rett [117][118][119]. However, the authors do note that the neuroanatomy of the Mecp2 KO mouse does have some differences compared with human patients.…”

A common MECP2 haplotype associates with reduced cortical surface area in humans in two independent populations

“…While the association is widespread, there do appear to be regions of increased MECP2 association. Based on mouse and human MECP2 mutation studies, we expected to see reductions in frontal and motor cortex size, and we do indeed observe this (6,9,12,17). Studies of females with Rett syndrome generally show occipital cortex preservation and dorsal-parietal cortical volume reduction (9), and we do not observe this.…”

“…While rare mutations in several genes result in reduced brain size, common polymorphisms in these genes have shown little or no replicated association with brain structure measures (4,5). We examined the association of brain structure measures with variants in and around the gene MECP2, chosen because of its role as a determinant of brain morphology in both humans and mice (6)(7)(8)(9). Located on Xq28, MECP2 encodes the methyl CpG binding protein 2, and mutations in this gene cause Rett syndrome (10), and are associated with other neurodevelopmental disorders including autism (11), mental retardation (12), and mild learning disabilities (13).…”

Generalized <i>α</i>-Entropy Based Medical Image Segmentation

“…Especially, algorithms for the delineation of anatomical structures and other regions of interest are a key component in assisting and automating specific radiological tasks. These algorithms, named image segmentation algorithms, play a fundamental role in many medical imaging applications such as the quantification of tissue volumes [3,4], diagnosis [5], localization of pathology [6,7], study of anatomical structure [8,9], treatment planning [10], partial volume correction of functional imaging data [11], and computer integrated surgery [12][13][14]. Techniques for carrying out segmentations vary broadly depending on some factors such as specific application, imaging modality, etc.…”