Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004134 (ataxia)
 15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Wernicke's encephalopathy is a syndrome characterized by ataxia, ophthalmoplegia, and confusion with thiamine deficiency. We reported on two Japanese brothers with a newly discovered recessively inherited syndrome similar to Wernicke's encephalopathy that developed in the second decade of life; this syndrome was manifested clinically as thiamine-responsive diplopia, ataxia and confusion without serum thiamine deficiency. The patients had complex partial seizure. The administration of high-dose thiamine improved these symptoms. MRI of the brain showed high-intensity signals in the bilateral medial thalamus and periaqueductal region on fluid-attenuated inversion recovery images; these signals were characteristic of findings in Wernicke's encephalopathy. There was no history of chronic alcoholism. The clinical and images features resembling Wernicke's encephalopathy in these patients suggested that the syndrome was caused by a genetic disorder of thiamine metabolism. Genomic analysis of SLC10A3 encoding human thiamine transporter 2 revealed that the patients were compound heterozygotes for the K44E and E320Q mutations. Gene-expression analyses of mammalian culture cells showed that intracellular thiamine uptake activities were decreased significantly. High expression of SLC19A3 RNA in the thalamus may explain the selective thalamic lesions on MRI. The identification of this syndrome proves insight into the thiamine metabolism associated with Wernicke's encephalopathy in humans.
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PMID:[Familial Wernicke's-like encephalopathy]. 2192 71

Thiamine, in the form of thiamine pyrophosphate, is a cofactor for a number of enzymes which play important roles in energy metabolism. Although dietary thiamine deficiency states have long been recognised, it is only relatively recently that inherited defects in thiamine uptake, activation and the attachment of the active cofactor to target enzymes have been described, and the underlying genetic defects identified. Thiamine is transported into cells by two carriers, THTR1 and THTR2, and deficiency of these results in thiamine-responsive megaloblastic anaemia and biotin-responsive basal ganglia disease respectively. Defective synthesis of thiamine pyrophosphate has been found in a small number of patients with episodic ataxia, delayed development and dystonia, while impaired transport of thiamine pyrophosphate into the mitochondrion is associated with Amish lethal microcephaly in most cases. In addition to defects in thiamine uptake and metabolism, patients with pyruvate dehydrogenase deficiency and maple syrup urine disease have been described who have a significant clinical and/or biochemical response to thiamine supplementation. In these patients, an intrinsic structural defect in the target enzymes reduces binding of the cofactor and this can be overcome at high concentrations. In most cases, the clinical and biochemical abnormalities in these conditions are relatively non-specific, and the range of recognised presentations is increasing rapidly at present as new patients are identified, often by genome sequencing. These conditions highlight the value of a trial of thiamine supplementation in patients whose clinical presentation falls within the spectrum of documented cases.
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PMID:Defects of thiamine transport and metabolism. 2478 39