Structural Imaging in Turner Syndrome.

In contrast to the well-described somatic effects associated with Turner syndrome, less is known about the neurobiology underlying the cognitive and behavioral features.

Neuroanatomical differences show that compared to controls, females with Turner syndrome have:

• Smaller region-to-whole brain proportions bilaterally for the parietal lobe
• Decreased hippocampus, lenticular nucleus, and thalamus
• Increased size of the 4th ventricle
• Decreasede cerebellar vermis and pons
• Increased bilateral ventricular volume
• Decreased corpus callosum (genu)
• Increased superior temporal gyrus (STG)

Given the neuropsychological findings and the limited imaging studies, we aim to explore structural differences in females with Turner syndrome relative to controls in the parietal and frontal lobes, particularly in the right hemisphere. In addition, we hope to further explain how these differences are associated with cognitive and behavioral findings. If you are interested in learning more about image processing procedures used in the Stanford Psychiatry Neuroimaging Laboratory, see the Tools page.

We are also studying genomic imprinting effects in Turner syndrome. Imprinting is a mechanism of gene regulation that causes differential gene expression. Specifically, whether or not an imprinted gene is expressed depends on its parental origin. Thus far, we have demonstrated that individuals with Turner syndrome who inherit the X chromosome from their mother (Xm) have significantly increased cerebellar gray matter and decreased occipital white matter compared to controls. Additionally, individuals with Xm may have significantly increased superior temporal gyrus volumes compared to those whose X chromosome was inherited from the father (Xp) and compared to controls.

We aim to explore structural differences in females with Turner syndrome relative to controls and relative to subjects with other genetic and developmental disorders. Our current research is particularly focused on the parietal and frontal lobes,superior temporal gyrus (STG), amygdala/hippocampus, and cerebellum. Using a newly evolving technique known as Diffusion Tensor Imaging, (DTI), we are also exploring neural connectivity. In addition, we hope to further explain how neuroanatomical differences are associated with cognitive and behavioral findings.