Rett syndrome: Novel correlations linking >96% genotype, disease severity, and seizures

Abstract

BACKGROUND: Rett Syndrome (RTT), an incurable neurodevelopmental disorder associated in >96% with the X-linked gene, MECP2 includes seizures, among its most difficult issues, impacting many features and increasing morbidity and mortality. Linking these seizures with clinical severity in RTT is critical for estimating risk and guiding therapy. OBJECTIVE: Our primary purpose was to identify associations between type and frequency of seizures, disease severity, and specific MECP2 mutations to address the hypothesis that seizure frequency correlates with specific mutations and directly impacts clinical severity. METHODS: Mutation, seizure type and frequency, and clinical severity assessed by the Clinical Severity Scale (CSS) were extracted from the 5211 Natural History Study of Rett Syndrome and Related Disorders [1]. This involved observations from 222 Persons with classic or variant RTT and MECP2 mutation positive non-Rett diagnoses. Descriptive analyses were assessed utilizing SPSS software. Mutations include R106W, R133C, R168X, R294X, R306C, other point mutations, and early truncations. RESULTS: Greater frequency of generalized seizures and seizures of any type were associated with R106W mutations; R168X mutations had the highest disease severity, and R133C mutations had the lowest disease severity. CONCLUSION: Important correlations exist across several common MECP2 mutations, including the novel association between generalized seizure frequency and mild CSS.