Slower pace in early walking onset is related to communication, motor skills, and adaptive function in autistic toddlers.

The onset of walking is a major developmental milestone in early childhood and is critical to the development of language and social communication. Delays in walking have been described in individuals with ASD. Yet, less is known about the quality of early gait development in toddlers with ASD and the relationship to motor skills, social communication, and language. Quantitative measures of locomotion can improve our ability to evaluate subtle and specific motor differences in toddlers with ASD and their relationship to other developmental domains. We used quantitative gait analysis to evaluate locomotion in toddlers with ASD (n = 51) and compared these data to a reference chronological aged (CA) and mental aged (MA) matched typically developing (TD) cohort (n = 45). We also examined the relationship of quantitative gait metrics to developmental measures among toddlers with ASD. We found that although toddlers with ASD achieved a typical age range of walking onset, they exhibited a pattern of slower pace compared to the TD cohort when matched by CA and MA. We also found that slower measures of pace were associated with lower developmental scores of communication, motor skills, and adaptive function. Our findings improve characterization of locomotion in toddlers with ASD and the relationship of motor skills to other developmental domains.

The Neurodevelopmental and Motor Phenotype of SCA21 (ATX-TMEM240).

Spinocerebellar ataxia type 21 (SCA21/ATX-TMEM240) is a rare form of cerebellar ataxia that commonly presents with motor, cognitive, and behavioral impairments. Although these features have been identified as part of the clinical manifestations of SCA21, the neurodevelopmental disorders associated with SCA21 have not been well studied or described. Here we present extensive phenotypic data for 3 subjects from an SCA21 family in the United States. Genetic testing demonstrated the c.196 G>A (p.Gly66Arg) variant to be a second recurrent mutation associated with the disorder. Standardized developmental assessment revealed significant deficits in cognition, adaptive function, motor skills, and social communication with 2 of the subjects having diagnoses of autism spectrum disorder, which has never been described in SCA21. Quantitative gait analysis showed markedly abnormal spatiotemporal gait variables indicative of poor gait control and cerebellar as well as noncerebellar dysfunction. Clinical evaluation also highlighted a striking variability in clinical symptoms, with greater ataxia correlating with greater severity of neurodevelopmental disorder diagnoses. Notably, neurodevelopmental outcomes have improved with intervention over time. Taken together, this case series identifies that the manifestation of neurodevelopmental disorders is a key feature of SCA21 and may precede the presence of motor abnormalities. Furthermore, the coexistence of ataxia and neurodevelopmental disorders in these subjects suggests a role for spinocerebellar pathways in both outcomes. The findings in this study highlight the importance of evaluation of neurodevelopmental concerns in the context of progressive motor abnormalities and the need for timely intervention to ultimately improve quality of life for individuals with SCA21.