CACNA1A and pathologic nystagmus: CACNA1A mutations have also been associated with severe neurodevelopmental syndromes including early-onset epilepsy (Early Infantile Epileptic Encephalopathy 42) and other neurocognitive (intellectual impairment, learning disabilities) and neurological symptoms, such as ataxia, nystagmus, hypotonia (Damaj et al., 2015; Epi4K Consortium, 2016; Epperson et al., 2018; Jiang X. et al., 2019).