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)

Hartnup disease is an inborn abnormality of renal and intestinal transport involving the neutral amino acids. Intermittent pellagra-like rash, attacks of cerebellar ataxia and psychiatric disturbance are characteristic symptoms of this disease. We described here a patient with adult-onset Hartnup disease who presented unique neuropsychiatric symptoms but no dermatologic symptoms, and reported features of amino acids transport in this patient and his family. The patient, a man aged 37 years, was referred to us because of lasting daytime bruxism. He is the second child of healthy parents who are first cousin; his elder brother who has been mentally retarded became bed-ridden and died at 32 years of age. His younger brother is completely healthy. Although the patient's development in infancy has been slightly retarded, he completed compulsory 9-year education. At 29 years of age, he experienced episodes of diplopia, ataxic gait and insomnia, and at 33 years of age, of transient stupor. There had been no history of photosensitivity or dermatitis. On neurological examination, there were trunkal ataxia, increased muscular tone and decreased mental activity besides bruxism. These symptoms remained unchanged despite of several medications including trihexyphenidyl, diazepam, halloperidol, tiapride and sulpiride. Two months later, the patient became stuporous; bruxism and hypertonicity became exaggerated. Myerson's sign, sucking reflex and grasp reflex in both hand appeared. There was no dermal lesion. A cranial computed tomography revealed a small calcification in the right frontal subcortical region and a single photon emission tomography indicated possible bifrontal hypoperfusion. Electroencephalograms demonstrated non-specific slowing. Somatosensory evoked potentials and nerve conduction velocities were normal. There were constant indicanuria and amino-aciduria.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Adult-onset Hartnup disease presenting with neuropsychiatric symptoms but without skin lesions]. 258 82

A 6-month-old girl developed intermittent dystonic posture of the legs and eczematous dermatitis without ataxia. Qualitative and quantitative urine amino acid testing confirmed the diagnosis of Hartnup disease. Cranial computed tomography, electroencephalogram, electromyogram/nerve conduction study, posterior tibial somatosensory evoked potentials, 24-hour electroencephalographic telemetry, and metrizamide myelogram were normal. Spinal fluid hydroxy-indoleacetic acid concentration was less than or equal to 2 S.D. of normal; oral tryptophan loading (70 mg/kg) resulted in a two-fold rise in cerebrospinal fluid 5-hydroxy-indoleacetic acid concentration. Tryptophan administered alone or with nicotinic acid failed to improve the dystonia; however, trihexyphenidyl (1-2 mg/kg/day) dramatically improved it. Hartnup disease should be considered in children with unexplained dystonia.
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PMID:Intermittent dystonia in Hartnup disease. 271 44

A 14-year-old boy of Arabic origin presented with a pellagra-like rash and neurological manifestations including ataxia, dysarthria, nystagmus, and coma. There was a striking response to oral nicotinamide. The laboratory findings were not typical of Hartnup disease: aminoaciduris and indicanuria were absent and there was no evidence of tryptophan malabsorption. Tryptophan loading did not induce tryptophanuria nor did it increase excretion of xanthurenic or kynurenic acids. These findings support the possibility of a block in tryptophan degradation. The family history suggests a genetically-determined disorder.
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PMID:Familial pellagra-like skin rash with neurological manifestations. 645 Dec 1

Hartnup disorder is caused by an inborn error of neutral amino acid transport in the kidneys and intestines. It is characterized by pellagra-like rash, ataxia, and psychotic behavior. Elevated urinary neutral amino acids are the first indicator of the disorder. SLC6A19 was identified as the causative gene in autosomal-recessive Hartnup disorder, which encodes the amino acid transporter B(0)AT1, mediating neutral amino acid transport from the luminal compartment to the intracellular space. Here, we report on a Korean boy aged 8 years and 5 months with Hartnup disorder, as confirmed by SLC6A19 gene analysis. He manifested seizures, attention-deficit hyperactivity disorder, and mental retardation without pellagra or ataxia. Multiple neutral amino acids were increased in his urine, and genetic analysis of SLC6A19 revealed compound heterozygous mutations, c.908C>T (p.Ser303Leu) and c.1787_1788insG (p.Thr596fsX73), both of which are novel. A novel SLC6A19 gene mutation was associated with late-onset seizures in a Korean patient with Hartnup disorder.
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PMID:Novel mutation in SLC6A19 causing late-onset seizures in Hartnup disorder. 2039 95

Mutations in the main intestinal and kidney luminal neutral amino acid transporter B(0)AT1 (Slc6a19) lead to Hartnup disorder, a condition that is characterized by neutral aminoaciduria and in some cases pellagra-like symptoms. These latter symptoms caused by low-niacin are thought to result from defective intestinal absorption of its precursor L-tryptophan. Since Ace2 is necessary for intestinal B(0)AT1 expression, we tested the impact of intestinal B(0)AT1 absence in ace2 null mice. Their weight gain following weaning was decreased, and Na(+)-dependent uptake of B(0)AT1 substrates measured in everted intestinal rings was defective. Additionally, high-affinity Na(+)-dependent transport of L-proline, presumably via SIT1 (Slc6a20), was absent, whereas glucose uptake via SGLT1 (Slc5a1) was not affected. Measurements of small intestine luminal amino acid content following gavage showed that more L-tryptophan than other B(0)AT1 substrates reach the ileum in wild-type mice, which is in line with its known lower apparent affinity. In ace2 null mice, the absorption defect was confirmed by a severalfold increase of L-tryptophan and of other neutral amino acids reaching the ileum lumen. Furthermore, plasma and muscle levels of glycine and L-tryptophan were significantly decreased in ace2 null mice, with other neutral amino acids displaying a similar trend. A low-protein/low-niacin diet challenge led to differential changes in plasma amino acid levels in both wild-type and ace2 null mice, but only in ace2 null mice to a stop in weight gain. Despite the combination of low-niacin with a low-protein diet, plasma niacin concentrations remained normal in ace2 null mice and no pellagra symptoms, such as photosensitive skin rash or ataxia, were observed. In summary, mice lacking Ace2-dependent intestinal amino acid transport display no total niacin deficiency nor clear pellagra symptoms, even under a low-protein and low-niacin diet, despite gross amino acid homeostasis alterations.
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PMID:Defective intestinal amino acid absorption in Ace2 null mice. 2279 May 97

The approach to the child with ataxia requires a detailed history and careful general and neurological examination as well as selected blood work and brain imaging and increasingly available genetic testing for inherited ataxias that usually have an episodic or progressive presentation. The differential of acute and recurring ataxia covered in this chapter includes intoxication (e.g., antiepileptics, lead, alcohol), postinfectious cerebellitis, hemorrhage, ischemic stroke, tumor (posterior fossa or cerebellum), brainstem encephalitis, occult neuroblastoma, Miller Fisher syndrome, conversion reaction, multiple sclerosis, epileptic pseudoataxia, vasculitis (e.g., Kawasaki), metabolic etiologies (e.g., maple syrup urine disease, pyruvate dehydrogenase deficiency, ornithine transcarbamylase deficiency, biotinidase deficiency, Hartnup disease, and argininosuccinic aciduria), migraine, migraine equivalents (benign paroxysmal positional vertigo), autosomal dominant episodic ataxias (with seven types currently identified), and hypothyroidism. Cooperation with therapists and providers from other specialties including ophthalmology and genetics and metabolism is essential to caring for these children and their families.
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PMID:Ataxia. 2362 31