Turner syndrome (TS) results from partial or complete X-monosomy and is characterized by deficits in visuospatial functioning as well as social cognition and memory. Neuroimaging studies have demonstrated volumetric differences in the parietal region of females with TS compared to controls. The present study examined amygdala and hippocampus morphology in an attempt to further understand the neural correlates of psychosocial and memory functioning in TS. Thirty females with TS age 7.6-33.3 years (mean = 14.7 ± 6.4) and 29 age-matched controls (mean age = 14.8 ± 5.9; range = 6.4-32.7) were scanned using high resolution MRI. Volumetric analyses of the MRI scans included whole brain segmentation and manual delineation of the amygdala and hippocampus. Compared to controls, participants with TS demonstrated significantly larger left amygdala gray matter volumes, irrespective of total cerebral tissue and age. Participants with TS also showed disproportionately reduced right hippocampal volumes, involving both gray and white matter. Amygdala and hippocampal volumes appear to be impacted by X-monosomy. Aberrant morphology in these regions may be related to the social cognition and memory deficits often experienced by individuals with TS. Further investigations of changes in medial temporal morphology associated with TS are warranted.

These findings suggest that X-monosomy and X-linked imprinting negatively affect STG development, possibly by disrupting neural pruning mechanisms.

Turner syndrome (TS) results from the absence of an X chromosome in females. This genetic condition is associated with specific cognitive deficits and variations in brain volumes. The goal of this study was to use high-resolution magnetic resonance imaging (MRI) to determine morphological variations in TS and to investigate the effects of parental origin of the X chromosome on brain development in TS. MRI brain scans were acquired from 26 girls with TS and 26 age- and gender-matched controls. Seventeen of the TS subjects had a maternally inherited X chromosome (Xm), and nine of the subjects had a paternally inherited X chromosome (Xp). Rater-blind morphometric analyses were conducted to compare tissue volume differences between girls with TS and controls. Three-way analyses were used to compare subgroups and controls. Subjects with TS demonstrated bilateral decreases in parietal gray and occipital white matter accompanied by increased cerebellar gray matter. Subjects with Xm showed decreased occipital white matter and increased cerebellar gray matter compared to controls. No differences were found in comparisons between subjects with Xp and controls or between subjects with Xm and Xp. Results suggest that X monosomy affects posterior cerebral and cerebellar anatomy in TS. While differences between comparisons of Xm and Xp to controls might suggest an imprinting effect, no significant differences were found when the two subgroups were directly compared to each other. Further investigation into the possible role of genomic imprinting is therefore warranted.

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Genetic or environmental factors other than abnormal X-inactivation must be involved in causing monozygous multiple gestation or CTS. Despite prenatal diagnosis, shared myocardium or cardiac anomalies in CTS often determine the prognosis.