Cognition in SCA21 reflects developmental and adult onset cerebellar cognitive affective syndrome: Table 1

Sir,We read with interest the article by Delplanque et al. (2014) entitled: ‘TMEM240 mutations cause spinocerebellar ataxia type 21 with mental retardation and severe cognitive impairment’. The striking feature of the clinical presentation was not only the cerebellar ataxia and cerebellar volume loss on imaging, but also the cognitive and neurobehavioural impairments that were pervasive, and—in the younger onset cases—severe enough to warrant the designation of severe mental retardation. The neuropsychological examinations of the SCA21 kindreds disclosed moderate impairments in attention, executive function, short-term, working and episodic memory abilities and, marked impairments in action planning, abstract reasoning, language and visuospatial functions. The authors also report neuropsychiatric phenomena including impulsivity, aggression and apathy etc.Despite the centrality of the cognitive and neurobehavioural features in this report of the genetic basis and clinical manifestations of SCA21, the authors do not reflect on the importance of their observations for our understanding of the wider role of the cerebellum beyond motor control, of which this case series represents …