Spatial cognition in males with Fragile-X syndrome: evidence for a neuropsychological phenotype.

Spatial performance in a group of young Fragile-X syndrome males with FMR-1 full mutation was compared to a learning disabled control group comprising young Down's syndrome males and two control groups of mainstream schoolchildren. Performance was assessed across a wide range of spatial tasks including visuo-construction, visuo-spatial memory, visuo-motor, and visuo-perception. The findings indicate a task-specific rather than global deficit in spatial performance in Fragile-X males with visuo-constructive and visuo-motor skills most vulnerable. Molecular analysis of the lymphocyte DNA found minimal evidence for a correlation between CGG expansion size and spatial performance, although tasks with a visuo-perceptual component correlated negatively with expansion size indicating that the further away the number of repeats are from the 200 threshold the poorer the performance.