Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cysteine-S-sulfate is an abnormal metabolite discovered in the urine and blood of a patient with cysteine oxidase deficiency, a rare disorder of sulfur amino acid metabolism associated with brain damage and mental retardation. The molecular structure of cysteine-S-sulfate closely resembles that of glutamate and related acidic amino acids which have both neuroexcitatory and neurotoxic properties (excitotoxic amino acids). Here we demonstrate that cysteine-S-sulfate induces the glutamate type of neuropathology in the rat central nervous system when administered subcutaneously to infants or intracerebrally to adults. It is postulated that cysteine-S-sulfate may be the neurotoxic agent responsible for brain damage in sulfite oxidase deficiency. The possibility that other excitotoxic amino acids could play occult roles in other unexplained neuropathologic conditions is discussed.
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PMID:Cysteine-S-sulfate: brain damaging metabolite in sulfite oxidase deficiency. 112 50

There are many causes of lens dislocation in man. Amongst these are two inborn errors of sulfur amino acid metabolism, viz., homocystinuria and sulfite oxidase deficiency. To date nine patients have been found in whom a combined deficiency of sulfite oxidase and xanthine dehydrogenase was observed. This inherited disease is due to a defective synthesis of molybdenum cofactor, an essential component for the assembly of both enzymes. The main clinical symptoms of these patients were: facial dysmorphic features, severe feeding difficulties, mental retardation, abnormal muscle tone, severe seizures and myoclonia. Four out of nine patients had dislocated eye lenses. The main biochemical findings included hypouricemia, xanthinuria, an increased excretion of sulfite, thiosulfate, S-sulfocysteine, taurine and a decreased excretion of inorganic sulfate. The prognosis of the disease is poor; various attempts at treatment were not successful so far. Prenatal diagnosis by assay of sulfite oxidase in cultured amniotic fluid cells and by direct measurement of amniotic fluid S-sulfocysteine is possible.
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PMID:Absence of hepatic molybdenum cofactor. An inborn error of metabolism associated with lens dislocation. 387 98

An infant who died with neurological abnormalities, mental retardation, and dislocated ocular lenses excreted in his urine abnormally large amounts of S-sulfo-L-cysteine, sulfite, and thiosulfate and virtulally no inorganic sutlfate. The present report establishes the occurrence of an ezymatic defect in this infant. His liver, brain, and kidney specifically lacked sulfite oxidase activity. Deficiency of sulfite oxidase, which has not apparently been described in man, provides a reasonable explanation for the abnormalities in this infant.
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PMID:Sulfite oxidase deficiency in man: demonstration of the enzymatic defect. 602 18

A patient suffering from a combined deficiency of sulfite oxidase (sulfite dehydrogenase; sulfite:ferricytochrome c oxidoreductase, EC 1.8.2.1) and xanthine dehydrogenase (xanthine:NAD+ oxidoreductase, EC 1.2.1.37) is described. The patient displays severe neurological abnormalities, dislocated ocular lenses, and mental retardation. Urinary excretion of sulfite, thiosulfate, S-sulfocysteine, taurine, hypoxanthine, and xanthine is increased in this individual, while sulfate and urate levels are drastically reduced. The metabolic defect responsible for loss of both enzyme activities appears to be at the level of the molybdenum cofactor common to the two enzymes. Immunological examination of a biopsy sample of liver tissue revealed the presence of the xanthine dehydrogenase protein in near normal amounts. Sulfite oxidase apoprotein was not detected by a variety of immunological techniques. The plasma molybdenum concentration was normal; however, hepatic content of molybdenum and the storage pool of active molybdenum cofactor present in normal livers were below the limits of detection. Fibroblasts cultured from this patient failed to express sulfite oxidase protein or activity, whereas those from the parents and healthy brother of the patient expressed normal levels of this enzyme.
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PMID:Inborn errors of molybdenum metabolism: combined deficiencies of sulfite oxidase and xanthine dehydrogenase in a patient lacking the molybdenum cofactor. 699 82

Molybdenum is found in most foods, with legumes, dairy products, and meats being the richest sources. This metal is considered essential because it is part of a complex called molybdenum cofactor that is required for the three mammalian enzymes xanthine oxidase (XO), aldehyde oxidase (AO), and sulfite oxidase (SO). XO participates in the metabolism of purines, AO catalyzes the conversion of aldehydes to acids, and SO is involved in the metabolism of sulfur-containing amino acids. Molybdenum deficiency is not found in free-living humans, but deficiency is reported in a patient receiving prolonged total parenteral nutrition with clinical signs characterized by tachycardia, headache, mental disturbances, and coma. The biochemical abnormalities in this acquired molybdenum deficiency include very low levels of uric acid in serum and urine (low XO activity) and low inorganic sulfate levels in urine (low SO activity). Inborn errors of isolated deficiencies of XO, SO, and molybdenum cofactor are described. Although XO deficiency is relatively benign, patients with isolated deficiencies of SO or molybdenum cofactor exhibit mental retardation, neurologic problems, and ocular lens dislocation. These abnormalities seem to be caused by the toxicity of sulfite and/or inadequate amounts of inorganic sulfate available for the formation of sulfated compounds present in the brain. XO and AO may also participate in the inactivation of some toxic substances, inasmuch as studies suggest that molybdenum deficiency is a factor in the higher incidence of esophageal cancer in populations consuming food grown in molybdenum-poor soil.
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PMID:Molybdenum: an essential trace element. 830 61

Molybdenum cofactor deficiency (MoCoD) is a fatal disorder manifesting, shortly after birth, with profound neurological abnormalities, mental retardation, and severe seizures unresponsive to any therapy. The disease is a monogenic, autosomal recessive disorder, and the existence of at least two complementation groups suggests genetic heterogeneity. In humans, MoCoD leads to the combined deficient activities of sulfite oxidase, xanthine dehydrogenase, and aldehyde oxidase. By using homozygosity mapping and two consanguineous affected kindreds of Israeli-Arab origin, including five patients, we demonstrated linkage of a MoCoD gene to an 8-cM region on chromosome 6p21.3, between markers D6S1641 and D6S1672. Linkage analysis generated the highest combined LOD-score value, 3.6, at a recombination fraction of 0, with marker D6S1575. These results now can be used to perform prenatal diagnosis with microsatellite markers. They also provide the only tool for carrier detection of this fatal disorder.
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PMID:Localization of a gene for molybdenum cofactor deficiency, on the short arm of chromosome 6, by homozygosity mapping. 963 14

Isolated sulfite oxidase deficiency is a rare autosomal recessive disease, characterized by severe neurological abnormalities, seizures, mental retardation, and dislocation of the ocular lenses, that often leads to death in infancy. There is a special demand for prenatal diagnosis, since no effective treatment is available for isolated sulfite oxidase deficiency. Until now, the cDNA sequence of the sulfite oxidase (SUOX) gene has been available, but the genomic sequence of the SUOX gene has not been published. In this study, we have performed a DNA-based diagnosis of isolated sulfite oxidase deficiency in a Chinese patient. To do so, we designed oligonucleotide primers for amplification of the predicted exons and intron-exon boundaries of the SUOX gene obtained from the completed draft version of the human genome. Using overlapping PCR products, we confirmed the flanking intronic sequences of the coding exons and that the entire 466-residue mature peptide is encoded by the last exon of the gene. We then performed mutation detection using denaturing high-performance liquid chromatography (DHPLC). The DHPLC chromatogram of exon 2b showed the presence of heteroduplex peaks only after mixing of the mutant DNA with the wild-type DNA, indicating the presence of a homozygous mutation. Direct DNA sequencing showed a homozygous base substitution at codon 160, changing the codon from CGG to CAG, which changes the amino acid from arginine to glutamine, i.e., R160Q. The DNA-based diagnosis of isolated sulfite oxidase deficiency will enable us to make an accurate determination of carrier status and to perform prenatal diagnosis of this disease. The availability of the genomic sequences of human genes from the completed draft human genome sequence will simplify the development of molecular genetic diagnoses of human diseases from peripheral blood DNA.
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PMID:DNA-based diagnosis of isolated sulfite oxidase deficiency by denaturing high-performance liquid chromatography. 1182 68