GRID2 and Nystagmus: Given that the ionotropic glutamate receptors are expressed selectively in the cerebellar Purkinje cells [17] and homozygous and compound heterozygous partial deletions of the GRID2 gene (exons 4 and 2) have been identified to cause nystagmus, hypotonia with developmental delay in gross motor skills, encephalopathy with cerebellar ataxia, oculomotor apraxia, and pyramidal tract involvement, the SARS-CoV-2 infection appears to be a second hit that elicited the observed phenotypes.