Intellectual functioning of children with Turner syndrome: a comparison of behavioural phenotypes.

This study reports the results of 19 girls with Turner syndrome (TS), aged between nine and 12 years, in relation to intellectual profile and genotypic variation. The results were consistent with the notion that the behavioural phenotype of mixed TS involving predominantly mosaic karyotypes is less deviant from the normal pattern than that of pure 45XO. The results for the pure TS girls were consistent with an exaggeration of a normal sex difference, but for mixed TS girls this effect was task-dependent. There was no evidence of generalised deficiency or immaturity, and the task-specific effects support modularity in the development of components of cognitive skill and spatial ability. They also support a specific overall intellectual profile in TS, but with considerable inter-individual variation in its expression.