SLC2A1 and biotinidase deficiency: For example, myoclonic seizures are seen in pyridoxine-dependent epilepsy, pyridoxal phosphate-responsive epilepsy, mitochondrial disorders, and glycine encephalopathy; infantile spasms are seen in serine biosynthesis defects, mitochondrial disorders, untreated phenylketonuria, and biotinidase deficiency; and generalized tonic-clonic seizures are seen in GLUT-1 deficiency, mitochondrial diseases, creatine deficiency syndromes, and biotinidase deficiency.