Do anomalies of handedness exist in children with Fragile-X syndrome?

Hand preference and skill were assessed in 27 children with Fragile-X syndrome, 30 children with Down's Syndrome, and 29 normal developing children. Three separate and specific anomalies of handedness that have been reported in other learning-disordered groups were examined: increased incidence of left-handedness; ambiguous or inconsistent handedness; and preference-skill discordance. The results revealed no difference between the subject groups in the distribution of left-handedness or ambiguous handedness. The main differences was the percentage of children who were discordant for hand preference and hand skill. In the Fragile-X group 37% preferred to use their right hand but demonstrated no overall difference in skilled performance between the hands. In contrast, only 13% of children with Down's Syndrome and 17% of normal controls showed this pattern of hand discordance. The results are discussed in the context of past research that has shown a similar dissociation of preference and skill in children with autism.