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)

A case is reported with a syndrome characterized by mental retardation, choreoathetosis, high levels of uric acid and aggressive, selfmutilation behavior, diagnosed as Lesch-Nyhan's syndrome. The most important features are, its appearance confined only to males, the absence of abnormalities along the prenatal and newborn periods, as well as the progressive impairment in the clinical course of the patient. The presence of high blood levels of uric acid which was controlled with the administration of allopurinol, the anemia, treated with ferrous sulfate and the complete absence of the AGPRT enzyme, were the laboratory findings. The clinical, pathophysiological and biochemical aspects of the treatment were also reviewed, as well as the experiences and findings reported in other series. The authors stress the very low frequency of these cases, the importance of making the diagnosis and the exceptional and eccentricity of the features which are part of the syndrome, such as the bites.
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PMID:[Lesch-Nyhan syndrome. Report of a case]. 87 31

Similar movement disorders developed in two 8-year-old retarded children while they were receiving phenytoin. Seizures subsequent to a diphtheria-pertussis-tetanus immunization had developed in each child at 1 to 2 months of age. A static encephalopathy ensued, characterized by mental retardation, ataxia, spasticity, and a mixed seizure disorder. Intermittent dystonia and choreoathetosis developed insidiously while serum phenytoin concentrations were in the therapeutic range. Sustained dystonia and choreoatheosis developed 2 hours after an oral provocation with phenytoin. The baseline abnormalities on the electroencephalogram remained unchanged during the choreoathetosis. Recognizable metabolic abnormalities known to be associated with similar movement disorders were excluded. It was concluded from these studies that the movement disorder is secondary to phenytoin and can occur at therapeutic serum concentrations. Phenytoin is a central anticholinergic agent and a central stimulant of serotonin, and may induce movement disorders as a result of altering these neurotransmitters in the brain. The variable expression of these movement disorders may relate to the nature of the preexisting striatal insult.
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PMID:Phenytoin-induced dystonia and choreoathetosis in two retarded epileptic children. 94 1

Hypoxanthine-guanine phosphoribosyltransferase (HPRT, EC 2.4.2.8) is a purine salvage enzyme that catalyses the conversion of hypoxanthine and guanine to their respective mononucleotides. Partial deficiency of this enzyme can result in the overproduction of uric acid leading to a severe form of gout, whilst a virtual absence of HPRT activity causes the Lesch-Nyhan syndrome which is characterised by hyperuricaemia, mental retardation, choreoathetosis and compulsive self-mutilation. The HPRT-encoding gene is located on the X chromosome in the region q26-q27 and consists of nine exons and eight introns totalling 57 kb. This gene is transcribed to produce an mRNA of 1.6 kb, which contains a protein encoding region of 654 nucleotides. With the advent of increasingly refined techniques of molecular biology, it has been possible to study the HPRT gene of individuals with a deficiency in HPRT activity to determine the genetic basis of the enzyme deficiency. Many different mutations throughout the coding region have been described, but in the absence of precise information on the three-dimensional structure of the HPRT protein, it remains difficult to determine any consistent correlation between the structure and function of the enzyme.
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PMID:A review of the molecular basis of hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency. 148 31

Lesch--Nyhan syndrome is an X-linked disease caused by the deficiency of hypoxanthine phosphoribosyltransferase, an enzyme involved in the purine salvage pathways. It is characterized by severe gout, choreoathetosis, self-mutilatory behaviour and mental retardation. The derivation of mice genetically deficient in this enzyme may help to elucidate the pathogenesis of the neurological abnormality where previously models using drug administration to mimic the disorder have had to suffice.
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PMID:Mouse models of hypoxanthine phosphoribosyltransferase deficiency. 152 24

We report on an infant (born to consanguineous parents) with an unusual face, microphthalmia, cleft palate, dextrocardia, choreoathetosis, and mental retardation. This child has many traits in common with an infant recently described by Aughton [1990] as a probable new syndrome.
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PMID:Dextrocardia, microphthalmia, cleft palate, choreoathetosis, and mental retardation in an infant born to consanguineous parents. 160 28

We report on a 4 generation family of individuals with an X-linked form of mental retardation involving 9 affected males and 5 obligate carrier females. Key manifestations include severe mental retardation, early hypotonia with progression to spasticity and contractures, choreoathetosis, seizures, presence of a long, narrow face with coarse features, cystic enlargement of the fourth ventricle with cerebellar hypoplasia (Dandy-Walker malformation), and iron accumulation in the basal ganglia with neuroaxonal dystrophy similar to Hallervorden-Spatz disease. Of the 5 known heterozygotes, 3 are dull intellectually, and one of the 3 developed a "presenile dementia." At autopsy she had iron deposition and neuroaxonal dystrophy in the basal ganglia and atrophy of the cerebral cortex. Although the clinical findings among relatives are variable, we conclude that this is a distinct, previously unrecognized X-linked mental retardation syndrome.
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PMID:New X-linked mental retardation disorder with Dandy-Walker malformation, basal ganglia disease, and seizures. 201 58

Lesch-Nyhan syndrome is a rare X-linked recessive disorder of purine metabolism associated with a virtually complete deficiency of the enzyme hypoxanthine-guanine phosphoribosyl-transferase (HPRT). The disease is characterized by hyperuricemia, self-multilation, choreoathetosis, spasticity, and mental retardation. The abnormalities of purine metabolism are present at birth and may lead to uric acid crystalluria and stone formation early in life. Radiographic findings described in Lesch-Nyhan syndrome include faintly radio-opaque stones on abdominal radiographs or, if renal disease is present, small kidneys with poor function on intravenous urogram. Radiolucent stones are usually composed of uric acid; however, several cases of xanthine and hypoxanthine-containing calculi in Lesch-Nyhan patients receiving allopurinl therapy have also been described. Oxypurine is the collective name for the compounds hypoxanthine, xanthine, and uric acid, and all may be radiolucent. We report a case of Lesch-Nyhan syndrome with presumed renal parenchymal oxypurine deposition demonstrated readily by ultrasonography but not detected on standard radiographs or intravenous urograms.
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PMID:Renal oxypurine deposition in Lesch-Nyhan syndrome: sonographic evaluation. 267 3

Severe deficiency of hypoxanthine phosphoribosyltransferase (HPRT) in man results in the Lesch-Nyhan syndrome, an X-linked neurological disorder characterized by mental retardation, choreoathetosis and a compulsive tendency towards self-mutilation. Although the HPRT gene is normally constitutively expressed in all tissues at low levels, expression is elevated approximately fourfold in several regions of the central nervous system, particularly in the basal ganglia. The relationships between HPRT deficiency, tissue-specific alterations of nucleotide metabolism and the neuropathology of the Lesch-Nyhan syndrome remain unclear. Here we have microinjected recombinant molecules containing human HPRT (hHPRT) complementary DNA, the mouse metallothionein-I (MT-I) promoter and the 3'-untranslated portion of the human growth hormone (hGH) gene into mouse embryos to produce transgenic animals that express hHPRT on induction by cadmium. The hHPRT cDNA in these experiments contained 88 base pairs (bp) of 5'-untranslated and 190 bp of 3'-untranslated sequences, and the full-length coding sequence. We studied the in vivo expression of this MT-hHPRT fusion gene and observed preferential hHPRT expression in tissues of the central nervous system (CNS). This study suggests that sequences within the hHPRT transcript (cDNA) influence CNS expression via increased synthesis or stability of messenger RNA.
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PMID:Expression of human HPRT in the central nervous system of transgenic mice. 299 15

Ten cases of Lesch-Nyhan syndrome have been followed for 3-19 years (mean, 11 years and four months). Criteria of Lesch-Nyhan syndrome were restricted to the following: complete absence of hypoxanthine-guanine phosphoribosyltransferase (HPRT) in hemolysate and fibroblast, spasticity, choreoathetosis, mental retardation, self-mutilation, and occurrence in males. Two patients have died of pneumonia and two died suddenly. However, autopsies produced no positive findings. Hyperuricemia has been controlled by benzbromarone in nine patients. One patient did not take any medical treatment and died suddenly when he was 19 years old, but showed no gouty signs. Patients with Lesch-Nyhan syndrome indicated no change or aggravation of choreoathetosis or spasticity. Self-mutilation was difficult to control by any treatment with continuing effect. After the age of ten, self-mutilation declined in seven cases, and in one patient disappeared completely. Mental delay was remarkable and suspected developmental age (DA) was 7 months - four years and 10 months (chronological age, 7 years and five months - 19 years and 6 months). Mean DQ score was 15.6. Physical development was severely delayed, and weight age was 28.9-46.4%, mean 37.4% of chronological age. Future investigations will evolve clarification of CNS signs and its treatment, and etiological research of sudden death.
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PMID:Long-term follow-up of ten patients with Lesch-Nyhan syndrome. 376 72

A sex-linked familial neurological disease consisting of cerebral palsy, mental retardation, choreoathetosis, and compulsive aggressive behavior is associated with a loss of an enzyme that participates in purine metabolism, namely, hypoxanthine-guanine phosphoribosyltransferase. The production of excessive uric acid in this disorder implies that the enzyme is involved in the normal regulation of purine biosynthesis. This is the first example of a relation between a specific enzyme defect and abnormal compulsive behavior. It is also the first enzyme defect in purine metabolism demonstrated in a neurological disease.
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PMID:Enzyme defect associated with a sex-linked human neurological disorder and excessive purine synthesis. 602 Feb 92


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