Structural Magnetic Resonance Imaging of Fragile X Syndrome.

Overview

Fragile X syndrome, the most common heritable cause of neuropsychiatric disability, is caused by a mutation of the FMR1 gene. Preliminary findings from imaging studies in our lab suggest an association between the FMR1 mutation and abnormalities of particular neuroanatomical regions.

Individuals with fragile X demonstrate morphological abnormalities of the cerebellar vermis, fourth and lateral ventricles, hippocampus, amygdala, and caudate nucleus. Putative dysfunction of these same brain regions in affected individuals is supported by findings in neurobehavioral studies and molecular genetic research investigating regional differences in activity of the FMR1 gene in the developing and mature mammalian brain, particularly increased expression in the hippocampus.

Current imaging research is designed to increase our knowledge of brain structure and function in fragile X syndrome. Our long-term goal is to use this information to help guide the design of more effective treatments for this disorder.

Structural Imaging

Materials and methods

The morphometric methods utilized in structural image processing and analysis in the Stanford Psychiatry Neuroimaging Laboratory (SPNL) incorporate semi- or fully automated procedures using our image processing program, BrainImage. Processing and segmentation of 3D-SPGR datasets is comprised of a set of semi-automated procedures that have been validated in our laboratory.

Regions of the hippocampus and amygdala delineated on MRI images.

The regions of interest generated from our image processing methods include volumes of: total brain, frontal lobe, parietal lobe, temporal lobe, occipital lobe, cerebellum, brainstem, ventricular volume, hippocampus, amygdala, parahippocampal gyrus and superior temporal gyrus. Segmented white matter, gray matter, and CSF image volumes are also measured for these areas.

More than 70 subjects with the full FMR1 mutation have been recruited by our lab for structural scanning. Concurrent functional (fMRI), behavioral, and hormonal data on these subjects also is gathered when possible. Image processing and analyses of this current data is ongoing.

More information on research

Several papers concerning structural imaging of fragile X syndrome are listed in selected fragile X syndrome publications.