Behavioral characteristics of individuals with Rett syndrome in Korea: A cross-sectional study

Rett syndrome (RTT) is a severe neurodevelopmental disorder caused by mutations in the MECP2 gene and characterized by developmental regression and stereotypic hand movements. We aimed to assess behavioral profiles in Korean individuals with RTT using caregiver-completed behavioral questionnaires. In this cross-sectional study, caregivers of 66 individuals with RTT completed the Korean version of the Rett Syndrome Behaviour Questionnaire (K-RSBQ, 45 items) and the Childhood Autism Rating Scale (CARS, 15 items). Descriptive statistics were used to summarize K-RSBQ total and subscale scores and CARS score distributions. Correlations between age and behavioral domains were also examined. This study represents a secondary analysis of anonymized survey data from a prior Korean RSBQ validation cohort. All 66 participants were female (mean age 12.89 ± 6.20 years; median 11.95, interquartile range 7.56-16.54). The median K-RSBQ total score was 41.5 (interquartile range 32.75-51.75). The hand behavior domain showed the highest score (8.71 ± 2.50 of 12), while nighttime behaviors and walking/standing showed lower scores. No K-RSBQ domain was significantly correlated with age. Several behavioral domains showed moderate inter-domain correlations, whereas hand behaviors appeared relatively independent. Among 58 participants who completed the CARS, 24 (41.4%) had scores in the severe autism range. Korean individuals with RTT demonstrated behavioral profiles characterized by prominent stereotypic hand movements and relatively stable behavioral patterns across age groups. These findings support the use of standardized caregiver-reported tools for characterizing behavioral phenotypes in RTT.