Rett syndrome is a neurological disorder mainly affecting females which although present from birth, may remain undetected until around one year of age. Many people with Rett syndrome have a mutation on the MECP2 gene on the X chromosome.

The authors of this study were interested in describing the Rett syndrome behavioural phenotype by using standardised behavioural measures. They used a variety of standardised measures to check whether autistic behaviour was prominent throughout childhood, whether autistic features were more significant in those who presented with milder signs and symptoms; whether the severity of the autistic behaviour was associated with other behavioural problems and whether there were any specific MECP2 mutations linked to more severe autistic behaviour.

The researchers worked with 80 girls who were diagnosed with Rett syndrome and tested positive for the MECP2 mutation, aged between aged 1.6–14.9 years old.

They administered the standardised measurement tests:

i. Screen for Social Interaction (SSI) which measures autistic behaviour
ii. Rett Syndrome Behaviour Questionnaire (RSBQ) which covers abnormal behaviours in the syndrome
iii. Vineland Adaptive Behavior Scales (VABS)
iv. modified Rett Syndrome Severity Scale (RSSS).

They also carried out regression analyses and T-tests.

They found that age had no significant effect on SSI or RSBQ total scores. The Vineland scale scores for socialization and the Composite scores however decreased over time. They also found that the clinical severity as measured by the severity scale increased with age. Performance in SSI was not found to be related to the scores in the severity scale or the Vineland composite scores. They found that autistic behaviour was weakly linked with the behaviour questionnaire hand behaviour factor scores, but not with the fear/anxiety factor in the same scale.

The authors conclude that from their study, autistic behaviour in Rett syndrome appeared to persist after the period of regression. Their data also suggested that neurological and behavioural impairments were independent of one another. They conclude that individual MECP2 mutations demonstrate complex associations with autistic features. They suggest that:

Evidence of persistent autistic behaviour throughout childhood, and of a link between hand function and social skills, has important implications not only for research on the RTT behavioural phenotype, but also for the clinical management of the disorder.”

Social impairments in Rett syndrome: characteristics and relationship with clinical severity, Kaufmann W et al., in Journal of Intellectual Disability Research, 56: 233–247.