THE NATURE OF THE SPATIAL DEFICIT IN YOUNG FEMALES WITH FRAGILE-X-SYNDROME - A NEUROPSYCHOLOGICAL AND MOLECULAR PERSPECTIVE

Spatial performance in a group of young Fragile-X syndrome females wit h FMR-1 full mutation was compared to two control groups of mainstream schoolchildren. Performance was assessed across a wide range of spati al tasks including visuo-spatial, visuo-construction, visuo-motor, vis uo-perception and spatial-memory. A spatial deficit emerged only on th ose tasks which comprised a visuo-constructive component, with the Fra gile-X group performing worse overall. All other tasks were performed at a comparable level across the three groups. Molecular analysis of t he lymphocyte DNA found minimal evidence for a correlation between exp ansion size and spatial performance. In addition, there was no evidenc e for a correlation between the proportion of active to inactive unmet hylated FMR-1 genes (activation ratio) and spatial performance. These results conflict with recent reports of a correlation between activati on ratio and intellectual functioning. (C) 1998 Elsevier Science Ltd. All rights reserved.