Neurodevelopmental effects of X monosomy: A volumetric imaging study

Abstract

Thirty girls with Turner syndrome (TuS) were compared with 30 individually age-matched controls on volumetric brain measures derived from magnetic resonance imaging and on measures of psychological functioning. As expected, girls with TuS performed more poorly on visual-spatial and intellectual measures relative to controls, and were rated by their parents as having more significant problems in attention and social behaviors. Although no group differences in overall cerebral or subcortical volumes were observed, the regional distribution of gray and white matter differed across groups in both right and left parietal regions. Differences in total tissue volume ratios were seen for both right and left parietal areas, but differences in individual gray and white matter ratios were seen exclusively in the right parietal regions. In general, girls with TuS had a smaller proportion of tissue (gray and white) within the right and left parietal regions, and a larger proportion of tissue within the right inferior parietal-occipital region relative to girls in the control group. These data suggest a potentially important role for X chromosome genes and/or sex steroids in the development and specialization of brain structure and function.

Selective Alterations of White Matter Associated with Visuospatial and Sensorimotor Dysfunction in Turner Syndrome

“…The SLF is a prominent white matter structure that extends in an arc above the insula from the frontal lobe to fan out into the parietal, occipital, and temporal lobes. Abnormal white matter within visuospatial pathways of the SLF is potentially consistent with volumetric studies of the parieto-occipital region in TS (Murphy et al, 1993;Reiss et al, 1995;Brown et al, 2002Brown et al, , 2004Molko et al, 2003). Functional imaging studies have shown that regions located within this pathway contribute to visuospatial processing.…”

“…Complementing the findings of atypical cerebral functioning seen in fMRI studies, neuroanatomic studies of TS have consistently found decreased gray matter volume in the bilateral parietal lobes, parieto-occipital region, and subcortical gray matter (Murphy et al, 1993;Reiss et al, 1995;Brown et al, 2002;Good et al, 2003;Kesler et al, 2003;Molko et al, 2003), as well as increased volume of the superior temporal gyrus (STG) (Kesler et al, 2003), amygdala (Kesler et al, 2004a,b), and orbitofrontal cortex (Good et al, 2003). Recent volumetric MRI localized parietal lobe findings to the bilateral superior parietal lobule and postcentral gyrus (Brown et al, 2004).…”

Three Parietal Circuits for Number Processing

“…A positron emission tomography study of five adult women demonstrated a glucose hypometabolism in bilateral parietal and occipital regions (Clark, Klonoff, & Hadyen, 1990). Two anatomical MR studies, one with 18 and the other with 30 affected women, demonstrated bilateral reductions in parieto-occipital brain volume, together with other subcortical regions (Murphy et al, 1993; see also Reiss et al, 1993;Reiss, Mazzocco, Greenlaw, Freund, & Ross, 1995). Interestingly, the phenotype of Turner syndrome can differ depending on whether the remaining X chromosome is of paternal or maternal origin (Xm or Xp subtypes; Bishop, Canning, Elgar, Morris, Jacobs, & Skuse, 2000;Skuse, 2000;Skuse et al, 1997).…”

A cognitive characterization of dyscalculia in Turner syndrome

“…A positron emission tomography study of five adult women demonstrated a glucose hypometabolism in bilateral parietal and occipital regions (Clark, Klonoff, & Hadyen, 1990). Two anatomical MR studies also demonstrated bilateral reductions in parieto-occipital brain volume, together with several other cortical and subcortical regions (Murphy et al, 1993;Reiss et al, 1993;Reiss, Mazzocco, Greenlaw, Freund, & Ross, 1995).…”