Social impairments in Rett syndrome: characteristics and relationship with clinical severity

• Published in: Journal of intellectual disability research 2012-03, Vol.56 (3), p.233-247
• Main Authors: Kaufmann, W. E., Tierney, E., Rohde, C. A., Suarez-Pedraza, M. C., Clarke, M. A., Salorio, C. F., Bibat, G., Bukelis, I., Naram, D., Lanham, D. C., Naidu, S.
• Format: Article
• Language: English
• Subjects: Adolescent; Adolescents; Age; Age Differences; Age Factors; Antisocial Behavior; Anxiety; Autism; Behavior Problems; Behavior Rating Scales; Behavioural problems; behavioural questionnaire; Biological and medical sciences; Child; Child clinical studies; Child, Preschool; Childhood; Children; Clinical management; clinical severity; Cohort Studies; Communication; Communication Problems; Data processing; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Developmental disorders; Disease management; Factor Analysis; Fear; Female; Females; Genetic Disorders; Genotype & phenotype; Hand; Humans; Infant; Infantile autism; Interaction; Interpersonal Competence; Interpersonal Relationship; Inventories; MeCP2 protein; Medical sciences; Mental retardation; Methyl-CpG binding protein; Methyl-CpG-Binding Protein 2 - classification; Methyl-CpG-Binding Protein 2 - genetics; Mutation; Mutation - genetics; Neurological disorders; Neurological Impairments; Neurology; Phenotype; Phenotypes; Physical Disabilities; Predictor Variables; Psychiatric Status Rating Scales; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Questionnaires; Regression (Psychology); Regression (Statistics); Regression analysis; Rett syndrome; Rett Syndrome - classification; Rett Syndrome - genetics; Rett Syndrome - physiopathology; Scores; Screening Tests; Severity; Severity (of Disability); Severity of Illness Index; Social Behavior; Social interactions; Social skills; Surveys and Questionnaires; Symptoms (Individual Disorders); T Test; Vineland Adaptive Behavior Scales
• ISSN: 0964-2633; 1365-2788
• DOI: 10.1111/j.1365-2788.2011.01404.x

Background  While behavioural abnormalities are fundamental features of Rett syndrome (RTT), few studies have examined the RTT behavioural phenotype. Most of these reports have focused on autistic features, linked to the early regressive phase of the disorder, and few studies have applied standardised behavioural measures. We used a battery of standardised measures of behaviour and functioning to test the following hypotheses: (1) autistic behaviour is prominent throughout childhood in RTT; (2) autistic features are more salient in individuals with milder presentation; (3) severity of autistic behaviour is associated with a wider range of behavioural problems; and (4) specific MECP2 mutations are linked to more severe autistic behaviour. Methods  Eighty MECP2 mutation‐positive girls with RTT (aged 1.6–14.9 years) were administered: (1) the Screen for Social Interaction (SSI), a measure of autistic behaviour suited for individuals with severe communication and motor impairment; (2) the Rett Syndrome Behaviour Questionnaire (RSBQ), covering a wide range of abnormal behaviours in RTT; (3) the Vineland Adaptive Behavior Scales (VABS); and (4) a modified version of the Rett Syndrome Severity Scale (RSSS). Regression analyses examined the predictive value of age and RSSS on autistic behaviour and other behavioural abnormalities. T‐tests further characterised the behavioural phenotype of individual MECP2 mutations. Results  While age had no significant effect on SSI or RSBQ total scores in RTT, VABS Socialization and Composite scores decreased over time. Clinical severity (i.e. RSSS) also increased with age. Surprisingly, SSI performance was not related to either RSSS or VABS Composite scores. Autistic behaviour was weakly linked with the RSBQ Hand behaviour factor scores, but not with the RSBQ Fear/Anxiety factor. Clinical (neurological) severity did not predict RSBQ scores, as evidenced by the analysis of individual MECP2 mutations (e.g. p.R106W, p.R270X and p.R294X). Conclusions  Our data suggest that in RTT, autistic behaviour persists after the period of regression. It also demonstrated that neurological and behavioural impairments, including autistic features, are relatively independent of one another. Consistent with previous reports of the RTT phenotype, individual MECP2 mutations demonstrate complex associations with autistic features. Evidence of persistent autistic behaviour throughout childhood, and of a link between hand function and social skills, h