ASNS and pathologic nystagmus: ASNS is a disease gene associated with asparagine synthetase deficiency (MIM: 615,574) and is a phenotype match for the proband, who presented with Lennox-Gastaut syndrome, infantile spasms, microcephaly, hypotonia, nystagmus, optic nerve hypoplasia, partial agenesis of the corpus callosum, and delayed myelination.