CACNA2D2 and Ataxia: In CACNA2D2, rare biallelic loss-of-function variation has been reported in individuals with DEE, corpus callosum hypoplasia, cerebellar atrophy and ataxia.9,10 The two unrelated patients reported here show considerable clinical overlap with individuals carrying homozygous CACNA2D2 loss-of-function variants, such as global developmental delay and/or intellectual disability, epilepsy and hypoplasia of the corpus callosum.