Longitudinal Evaluation of the Stability of Hand Function in Rett Syndrome

Abstract

To investigate the longitudinal stability of hand function in Rett syndrome and to analyze further the relationships between stability of hand function and genotype, age, and walking ability. Longitudinal video data of functional abilities of individuals with genetically confirmed Rett syndrome were collected by families of individuals registered with the Australian Rett Syndrome Database. A total of 120 individuals provided 290 recordings from which 170 observation pairs were available for comparison. The Rett Syndrome Hand Function Scale was used to classify a level of hand function observed in each video on a range from unable to grasp, pick up, and hold objects to skillful manipulation of large and small objects. Approximately one-third of the population lost some hand function over time. Younger children (<6years) rather than adults were at greater risk of deterioration in hand function. Clinical severity, as indicated by walking ability or genotype, played a lesser role. There was no identified pattern between genotype and the stability of hand function skills. Rather, mutations associated with milder (p.Arg133Cys, p.Arg294∗) and greater (p.Arg106Trp, p.Thr158Met) clinical severity were both associated with greater risks of decline. Genotype was a lesser predictor of loss of hand function beyond the early regression period, and younger children were particularly vulnerable to further loss of hand function compared with adults.