GLUT1 deficiency syndrome 1: A neurologic disorder showing wide phenotypic variability. The most severe 'classic' phenotype comprises infantile-onset epileptic encephalopathy associated with delayed development, acquired microcephaly, motor incoordination, and spasticity. Onset of seizures, usually characterized by apneic episodes, staring spells, and episodic eye movements, occurs within the first 4 months of life. Other paroxysmal findings include intermittent ataxia, confusion, lethargy, sleep disturbance, and headache. Varying degrees of cognitive impairment can occur, ranging from learning disabilities to severe mental retardation.
GLUT1 deficiency syndrome 2: A clinically variable disorder characterized primarily by onset in childhood of paroxysmal exercise-induced dyskinesia. The dyskinesia involves transient abnormal involuntary movements, such as dystonia and choreoathetosis, induced by exercise or exertion, and affecting the exercised limbs. Some patients may also have epilepsy, most commonly childhood absence epilepsy. Mild mental retardation may also occur. In some patients involuntary exertion-induced dystonic, choreoathetotic, and ballistic movements may be associated with macrocytic hemolytic anemia.
Epilepsy, idiopathic generalized 12: A disorder characterized by recurring generalized seizures in the absence of detectable brain lesions and/or metabolic abnormalities. Generalized seizures arise diffusely and simultaneously from both hemispheres of the brain. Seizure types include juvenile myoclonic seizures, absence seizures, and generalized tonic-clonic seizures. In some EIG12 patients seizures may remit with age.
Dystonia 9: An autosomal dominant neurologic disorder characterized by childhood onset of paroxysmal choreoathetosis and progressive spastic paraplegia. Most patients show some degree of cognitive impairment. Other variable features may include seizures, migraine headaches, and ataxia.
Stomatin-deficient cryohydrocytosis with neurologic defects: A rare form of stomatocytosis characterized by episodic hemolytic anemia, cold-induced red cells cation leak, erratic hyperkalemia, neonatal hyperbilirubinemia, hepatosplenomegaly, cataracts, seizures, mental retardation, and movement disorder.
