Sensory impairment and head circumference in Fragile X syndrome, Down syndrome and Idiopathic intellectual disability

Abstract

This study attempted to replicate reports of associations of enlarged head circumference and sensory problems with boys with fragile X syndrome. Eighteen boys with fragile X syndrome were compared with 42 boys of similar age and developmental ability but negative on testing for fragile X syndrome (''idiopathic intellectual disability'') and 45 boys with Down syndrome. Boys with Down syndrome had significantly more sensory problems than both other groups. Head circumferences of boys with fragile X syndrome and with idiopathic intellectual disability were both slightly larger than expected for age with similar means and distributions. Boys with Down syndrome had smaller heads than expected for age. This relatively small series suggests that a large head circumference may not always be diagnostically helpful especially in comparing boys with fragile X syndrome with others who have non-specific intellectual disability, and can not be relied upon as a consistent feature.