Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028738 (nystagmus)
 7,431 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glutamic acid decarboxylase (GAD) is the enzyme that catalyzes the conversion of glutamic acid to the neurotransmitter gamma-amino butyric acid. Antibodies against GAD (anti-GAD-Ab) are associated with an array of autoimmune-related neurological conditions, such as stiff-person syndrome, cerebellar ataxia, epilepsy and limbic encephalitis. The clinical spectrum of ataxia associated with anti-GAD-Ab comprises slowly progressive cerebellar ataxia syndrome evolving in months or years, associated with cerebellar atrophy on brain MRI. There are few reports of patients with ataxia associated with anti-GAD-Ab presenting with abnormal ocular movements, such as downbeat nystagmus (DBN).We present two patients with ataxia associated with anti-GAD-Ab from a large series of ataxic subjects who presented with cerebellar ataxia combined with spontaneous DBN. All patients underwent a thorough neurological evaluation with the use of ataxia scales, brain MRI scans, cerebrospinal fluid examination, 18FDG-PET/CT scans, laboratory work-up with on coneural and immune encephalitis antibodies, serum and cerebrospinal fluid levels of anti-GAD-Ab, and the antibody specificity index to measure the intrathecal synthesis of anti-GAD-Ab. All patients were treated with cycles of intravenous immunoglobulin and had mild/partial ataxia improvement and no improvement of DBN. The finding of DBN may work as a diagnostic clue in the context of adult-onset non-hereditary ataxias.
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PMID:Spontaneous downbeat nystagmus as a clue for the diagnosis of ataxia associated with anti-GAD antibodies. 2667 Oct 81

Paucity in gamma-amino butyric acid (GABA) due to blockage in the action of glutamic acid decarboxylase (GAD), as seen in the syndrome of anti-GAD antibody, causes adult onset cerebellar ataxia, muscle rigidity, and episodic spasms. Downbeat nystagmus, saccadic dysmetria, impaired ocular pursuit, and impaired cancelation of vestibular ocular reflex are typical ocular motor deficits in patients with syndrome of anti-GAD antibody. We describe opsoclonus, in addition to downbeat nystagmus, in a patient with increased titers of anti-GAD antibody. Paucity in GABA leading to disinhibition to Purkinje target neurons at deep cerebellar and vestibular nuclei might have caused downbeat nystagmus in our patient. Anti-GAD antibody can also increase levels of glutamate the precursor of GABA and the substrate for the action of GAD. We propose that opsoclonus might be due to increased levels of glutamate and subsequent hyperexcitability of excitatory and inhibitory burst neurons leading to reverberation in their reciprocally innervating circuit.
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PMID:Opsoclonus in a patient with increased titers of anti-GAD antibody provides proof for the conductance-based model of saccadic oscillations. 2694 42