Fragile X syndrome has a characteristic behavioural and physical phenotype. Clinical experience and case reports suggest that boys with premutations and intermediate alleles may have similar, but possibly milder, clinical features than those with the full mutation. We conducted detailed physical, psychiatric, psychological and speech and language evaluations on a clinical series of 10 boys, with either premutation or intermediate CGG triplet expansions. Wherever possible we measured the levels of FMR1 protein in participants' hair roots. Many participants demonstrated striking resemblance in their clinical picture, behavioural and physical, to individuals with the fragile X syndrome full mutation. However, protein expression was normal in all participants where it was assessed, despite large variation in CGG triplet repeats. We propose that the findings are unlikely to be attributable to ascertainment bias alone. Replication on larger independent samples is required to confirm our impression that fragile X premutations and intermediate alleles may be associated with important developmental disabilities and physical features.
Fragile-X syndrome is the most common genetically inherited cause of intellectual disability. People with this syndrome typically show a behavioural profile of abnormal social interactions which are similar in some ways to those seen in people with autism. The present study investigated whether cognitive processes which have been hypothesized to underlie social abnormalities associated with autism are also impaired in boys with fragile-X syndrome without autistic spectrum disorders. Eight boys with fragile-X syndrome and eight with intellectual disability of unknown aetiology, matched on receptive verbal ability, age and with no diagnosis of autism, were tested on a battery of theory of mind and executive function tasks. Significantly more boys with fragile-X syndrome failed the simplest theory of mind task. However, this could be attributed to overall level of ability rather than group membership. No differences were found between the groups on any other measures used. A proportion of both groups failed first- and second-order false belief tasks. The performance of both groups on the executive function measure was at the floor of the test. At low levels of overall ability, the performance of boys with fragile-X syndrome and boys with intellectual disability of unknown aetiology may be more similar than they are different The implication of this result for clinical interventions is discussed.
The purpose of this study was to increase simple toy play in profoundly mentally handicapped children by presenting them with specially designed toys. Twenty children (mean chronological age 14 years, mean mental age less than 1 year) were observed while playing with the special toys, which emitted stimuli (vibration, light, or sound) when appropriately operated. They were also observed with the toys when the stimuli were unavailable. There were large individual differences, but, in general, children interacted significantly more with the experimental toys than with the control toys and engaged in significantly less stereotyped behavior when the experimental toys were available. The implications for clinical and research work are discussed.
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