Turner syndrome: Neuroimaging findings: Structural and functional

Department of Psychiatry, Research and Education Centre, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin 9, Ireland.
Developmental Disabilities Research Reviews (Impact Factor: 2.79). 01/2009; 15(4):279-83. DOI: 10.1002/ddrr.87
Source: PubMed

ABSTRACT Neuroimaging studies of Turner syndrome can advance our understanding of the X chromosome in brain development, and the modulatory influence of endocrine factors. There is increasing evidence from neuroimaging studies that TX individuals have significant differences in the anatomy, function, and metabolism of a number of brain regions; including the parietal lobe; cerebellum, amygdala, hippocampus; and basal ganglia; and perhaps differences in "connectivity" between frontal and parieto-occipital regions. Finally, there is preliminary evidence that genomic imprinting, sex hormones and growth hormone have significant modulatory effects on brain maturation in TS.

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    ABSTRACT: There is increasing evidence that genomic imprinting, a process by which certain genes are expressed in a parent-of-origin-specific manner, can influence neurogenetic and psychiatric manifestations. While some data suggest possible imprinting effects of the X chromosome on physical and cognitive characteristics in humans, there is no compelling evidence that X-linked imprinting affects brain morphology. To address this issue, we investigated regional cortical volume, thickness, and surface area in 27 healthy controls and 40 prepubescent girls with Turner syndrome (TS), a condition caused by the absence of one X chromosome. Of the young girls with TS, 23 inherited their X chromosome from their mother (X(m)) and 17 from their father (X(p)). Our results confirm the existence of significant differences in brain morphology between girls with TS and controls, and reveal the presence of a putative imprinting effect among the TS groups: girls with X(p) demonstrated thicker cortex than those with X(m) in the temporal regions bilaterally, while X(m) individuals showed bilateral enlargement of gray matter volume in the superior frontal regions compared with X(p). These data suggest the existence of imprinting effects of the X chromosome that influence both cortical thickness and volume during early brain development, and help to explain variability in cognitive and behavioral manifestations of TS with regard to the parental origin of the X chromosome.
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    ABSTRACT: Recently, there has been a wealth of research into structural and functional brain connectivity, and how they change over development. While we are far from a complete understanding, these studies have yielded important insights into human brain development. There isan evergrowing variety of methods for assessing connectivity, each with its own advantages. Here we review research on the development of structural and/or functional brain connectivity in both typically developing subjects and subjects with neurodevelopmental disorders. Space limitations preclude an exhaustive review of brain connectivity across all developmental disorders, so we reviewa representative selection of recent findingson brain connectivity in autism, Fragile X, 22q11.2 deletion syndrome, Williams syndrome, Turner syndrome, and ADHD. Major strides have been made in understandingthe developmental trajectory of the human connectome, offering insight intocharacteristic features of brain development and biological processesinvolved in developmental brain disorders. We also discuss some common themes, includinghemispheric specialization - or asymmetry - and sex differences. We conclude by discussing some promising future directions in connectomics, including the merger of imaging and genetics, and a deeper investigation of the relationships between structural and functional connectivity.
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    ABSTRACT: The aim of the study was to assess physical fitness of girls with Turner syndrome (TS) and to determine the relative contributions of age, body height, and body mass to performance in fitness tests. Girls with TS aged 10-18 years (n = 184), and age- and stature-matched healthy controls (n = 280) were studied with the use of the EUROFIT test battery. Girls with TS were significantly inferior to the control group in maintaining balance, standing broad jump, sit-ups, shuttle run, and endurance shuttle run (p < .001). No significant differences were found for plate tapping, but girls with TS were superior to their healthy mates (p < .001) in handgrip, sit-and-reach, and bent-arm hang. Unlike controls, body height in girls with TS had significant effects on handgrip strength (positive) and on plate tapping speed (negative), other contributions being relatively similar in both groups. It thus seems that the somatic specificity of girls with TS explains most differences in motor fitness. The identified motor deficiencies of girls with TS call for undertaking steps toward attracting those girls to motor activities.
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