Turner syndrome is a genetic disorder caused by the complete or partial absence 
of an X chromosome in affected women. Individuals with TS show characteristic 
difficulties with executive functions, visual-spatial and mathematical 
cognition, with relatively intact verbal skills, and congruent abnormalities in 
structural development of the posterior parietal cortex (PPC). The functionally 
heterogeneous PPC has recently been investigated using connectivity-based 
clustering methods, which sub-divide a given region into clusters of voxels 
showing similar structural or functional connectivity to other brain regions. In 
the present study, we extended this method to compare connectivity-based 
clustering between groups and investigate whether functional networks 
differentially recruit the PPC in TS. To this end, we parcellated the PPC into 
sub-regions based on temporal correlations with other regions of the brain. fMRI 
data were collected from 15 girls with TS and 14 typically developing (TD) 
girls, aged 7-14, while they performed a visual-spatial task. Temporal 
correlations between voxels in the PPC and a set of seed regions were 
calculated, and the PPC divided into clusters of voxels showing similar 
connectivity. It was found that in general the PPC parcellates similarly in TS 
and TD girls, but that regions in bilateral inferior parietal lobules, and 
posterior right superior parietal lobule, were reliably recruited by different 
networks in TS relative to TD participants. These regions showed weaker 
correlation in TS with a set of regions involved in visual processing. These 
results suggest that abnormal development of visuospatial functional networks in 
TS may relate to the well documented cognitive difficulties in this disorder.