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 13-year-old girl with Fahr disease (infantile form) was reported. Her parents were consanguineous. Her elder sister had mental retardation and spasticity of the lower limbs, and died at 23 years of age. The patient suffered from infantile spasms at 3 month. She was bed-ridden, nonverbal, microcephalic and blind. Cranial CT revealed massive calcifications in the basal ganglia, periventricular white matter, dentate nucleus and cerebellar white matter. EEG showed a suppression-burst pattern. At 13 years, she died of pneumonia and hyperammonemia. Microscopic examination of brain showed perivascular non-arteriosclerotic ferro-calcinosis. The periventricular granules are 1-4 mu or 12 mu in diameter. This pathological change was observed only in the central nervous system above midbrain. No calcifications were found in the pituitary and the vessels of pia mater. Also a reduced ornithine transcarbamylase activity was found in the liver, which was probably not related with cerebral calcifications. Infantile form of Fahr disease is rare and may be heterogeneous in etiology. However, clinical manifestations and pathological findings were similar to those in previous reports of Fahr disease in childhood. It is one of the disorders causing infantile spasms.
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PMID:[An autopsy case of Fahr disease (infantile form)]. 152 May 12

In a retrospective survey done from 1978-1988 in Japan, 32 male patients with ornithine transcarbamylase (OTC) deficiency were identified. We classified a neonatal and 2 late-onset groups, depending on clinical manifestations and the age at onset; group 1 (0-28 days; N = 10), group 2 (29 days-5 years; N = 13), and group 3 (greater than 5 years; N = 9). Compared to findings in the group 2 patients, there was a higher rate of mortality and a higher incidence of mental retardation in association with a great decrease in enzyme activity in group 1. In group 3, the mortality rate and enzyme activities were similar to those in group 1. However, patients in this group were asymptomatic prior to the first episode. Enzyme activities were measured mostly in autopsy samples. The serum citrulline levels (enzyme product) were highest in this group. Thus, the mutant enzymes were apparently labile with greater activities in vivo than in vitro. Treatments, including a protein-restricted diet, arginine supplementation, and sodium benzoate administration, resulted in a favorable prognosis for survivors with partial enzyme deficiency. We wish to emphasize that the incidence of late onset of this disease is higher than heretofore considered.
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PMID:Retrospective survey of urea cycle disorders: Part 1. Clinical and laboratory observations of thirty-two Japanese male patients with ornithine transcarbamylase deficiency. 201 37

Five male Japanese patients with complex glycerol kinase deficiency (CGKD) and their relatives were studied clinically, cytogenetically, and molecular-genetically. All patients had muscular dystrophy or muscle weakness, mental retardation, congenital adrenal hypoplasia, and glycerol kinase deficiency. High-resolution GTG-banded chromosomes showed a microdeletion in the Xp21 region in all four patients examined and in all five mothers. Southern hybridizations, after digestions by restriction endonucleases, with various cloned DNAs (D2, 99-6, B24, C7, L1-4, cDMD13-14, J66-HI, P20, J-Bir, ERT87-30, ERT87-15, ERT87-8, ERT87-1, XJ-1.1, 754, cx5.7, and OTC-1) that are located around Xp21 also showed a deletion in the genome of all patients and mothers. Although the deletion differed in size among patients, a segment commonly absent was located between the genomic sequences corresponding to L1-4 and cDMD13-14. This finding indicated that the gene coding for glycerol kinase (GK) is located within this segment. A comparison of the clinical manifestations of the present five patients and reported CGKD or Duchenne muscular dystrophy (DMD) patients with DNA deletion suggests the existence of a certain gene responsible for gonadotropin deficiency (GTD). The result of the present study and results of previous studies suggest that genes for ornithine transcarbamylase (OTC), DMD, and GK and putative genes responsible for congenital adrenal hypoplasia (AHC) and GTD are arranged from telomere to centromere as pter--GTD--AHC--GK--DMD--OTC--cen.
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PMID:Complex glycerol kinase deficiency: molecular-genetic, cytogenetic, and clinical studies of five Japanese patients. 285 74

Congenital ornithine transcarbamylase (OTC) deficiency in humans is associated with seizures and mental retardation. As part of a series of studies to delineate the neurochemical features of OTC deficiency, activities of choline acetyltransferase (ChAT) and acetylcholinesterase (AChE), respectively, were measured in brain regions of the congenitally hyperammonemic sparse-fur (spf) mouse, a mutant with an X-linked inherited defect of OTC. ChAT activities were reduced by 63% (P < 0.01) in cerebral cortex of spf mice compared with CD-1/Y controls. Activities of the GABA nerve terminal marker enzyme, glutamic acid decarboxylase, on the other hand, were within normal limits. Using an immunohistochemical technique with a monoclonal antibody to ChAT, a significant loss of ChAT-positive neurons was observed throughout the cerebral cortex, septal area and diagonal band of spf mice. These results suggest that a loss of forebrain cholinergic neurons is a feature of congenital OTC deficiency in these mutants. Possible pathogenetic mechanisms responsible for the cholinergic neuronal loss in congenital OTC deficiency include neurotoxic effects of ammonia and accumulation of quinolinic acid.
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PMID:Evidence for cholinergic neuronal loss in brain in congenital ornithine transcarbamylase deficiency. 781 42

Congenital deficiencies of the urea cycle enzyme ornithine transcarbamylase (OTC) result in chronic hyperammonemia and severe neurological dysfunction including seizures and mental retardation. As part of a series of studies to elucidate the pathophysiologic mechanisms responsible for the CNS consequences of OTC deficiency, concentrations of ammonia-related and neurotransmitter amino acids were measured as their o-phthalaldehyde derivatives using high performance liquid chromatography with fluorescence detection in regions of the brains of sparse-fur (spf) mice, a mutant with an X-linked inherited defect of OTC. Compared to CD-1/Y controls, the brains of spf/Y mutant mice contained significant alterations of several amino acids. A generalized, up to 2-fold, increase of brain glutamine was observed, consistent with the exposure of these brains to increased concentrations of ammonia. Significant increases of brain alanine were also observed and, together with previous reports of increased concentrations of alpha-ketoglutarate, are consistent with ammonia-induced inhibition of alpha-ketoglutarate dehydrogenase in the brains of spf/Y mice. Increased brain content of the excitatory amino acid aspartate could be responsible for the seizures frequently encountered in congenital OTC deficiency.
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PMID:Regional amino acid neurotransmitter changes in brains of spf/Y mice with congenital ornithine transcarbamylase deficiency. 791 68

Xp21 microdeletion syndrome is associated with variable size Xp21 deletions that usually include the glycerol kinase locus. The clinical phenotypes we studied in this chromosome region include: Xpter - Aland Island eye disease (AIED) -adrenal hypoplasia (AH) -glycerol kinase (GKD) -Duchenne muscular dystrophy (DMD) -retinitis pigmentosa (RP) -ornithine transcarbamylase (OTC) -centromere. In a compilation of 18 individuals in 14 families with the AH, GKD, and DMD loci deleted, 17 were male and all were developmentally delayed. In contrast, we report mentally retarded female carriers in two Xp21 deletion syndrome families with DMD, GKD, and AH in affected males. In the first family with normal karyotypes, a submicroscopic deletion was associated with DMD in the retarded male and with retardation in carrier females. In the second family an X chromosome with a cytogenetically deleted Xp21 distal to the OTC and RP genes segregated in the affected male and retarded female carriers. DNA analysis at the DMD locus verified the cytogenetic findings. This report of mental retardation in otherwise asymptomatic female carriers of Xp21 deletion classifies one form of mental retardation in females.
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PMID:Mental retardation locus in Xp21 chromosome microdeletion. 835 5

The reproductive effects of metabolic disorders in women can be divided into four categories. The first of these is infertility. Galactosemia with its complication of ovarian failure is the disorder in this category. This complication may be prenatal in origin but whether this is so and its cause are unknown. The second category includes pregnancy effects of maternal metabolic disorders. The urea cycle disorder ornithine transcarbamylase (OTC) deficiency, maternal maple syrup urine disease and maternal homocystinuria are in this category. In the first two disorders, postpartum life-threatening illness due to metabolic crisis has occurred. Maternal homocystinuria is associated with a high risk for postpartum thromboembolic complications. The third category is the pregnancy effect of a fetal metabolic disorder. Pregnancies in which the fetus had long-chain hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) have been complicated by the life-threatening (HELLP) syndrome during the third trimester. Rapid recovery of the mothers followed delivery, on occasion by emergency cesarean section. The fourth category is the fetal effects (teratogenicity) from a maternal metabolic disorder. The best-known example of this is maternal phenylketonuria (PKU), which produces microcephaly, mental retardation, congenital heart disease and intrauterine growth retardation. Treatment with a low phenylalanine diet begun before conception or no later than the earliest weeks of the first trimester markedly reduces the risk to the fetus and can result in normal offspring. Other examples of teratogenicity may include maternal homocystinuria and maternal hypothyroidism.
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PMID:Reproductive effects of maternal metabolic disorders: implications for pediatrics and obstetrics. 882 3

As a toxic metabolic byproduct in mammals, excess ammonia is converted into urea by a series of five enzymatic reactions in the liver that constitute the urea cycle. A portion of this cycle takes place in the mitochondria, while the remainder is cytosolic. Liver arginase (L-arginine ureahydrolase, A1) is the fifth enzyme of the cycle, catalyzing the hydrolysis of arginine to ornithine and urea within the cytosol. Patients deficient in this enzyme exhibit hyperargininemia with episodic hyperammonemia and long-term effects of mental retardation and spasticity. However, the hyperammonemic effects are not so catastrophic in arginase deficiency as compared to other urea cycle defects. Earlier studies have suggested that this is due to the mitigating effect of a second isozyme of arginase (AII) expressed predominantly in the kidney and localized within the mitochondria. In order to explore the curious dual evolution of these two isozymes, and the ways in which the intriguing, aspects of AII physiology might be exploited for gene replacement therapy of AI deficiency, the cloned cDNA for human AI was inserted into an expression vector downstream from the mitochondrial targeting leader sequence for the mitochondrial enzyme ornithine transcarbamylase and transfected into a variety of recipient cell types. AI expression in the target cells was confirmed by northern blot analysis, and competition and immunoprecipitation studies showed successful translocation of the exogenous AI enzyme into the transfected cell mitochondria. Stability studies demonstrated that the translocated enzyme had a longer half-life than either native cytosolic AI or mitochondrial AII. Incubation of the transfected cells with increasing amounts of arginine produced enhanced levels of mitochondrial AI activity, a substrate-induced effect that we have previously seen with native AII but never AI. Along with exploring the basic biological questions of regulation and subcellular localization in this unique dual-enzyme system, these results suggest that the mitochondrial matrix space may be a preferred site for delivery of enzymes in gene replacement therapy.
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PMID:Delivery of cytosolic liver arginase into the mitochondrial matrix space: a possible novel site for gene replacement therapy. 913 Oct 18

Congenital ornithine transcarbamylase (OTC) deficiency is the most common inborn error of urea cycle enzymes in humans. A large percentage of survivors of neonatal OTC deficiency suffer severe developmental disorders, including seizures, mental retardation and cerebral palsy. Neuropathological studies reveal ventricular enlargement, cerebral atrophy and delayed myelination, as well as Alzheimer type II astrocytosis. Using the sparse-fur (spf) mouse model of congenital OTC deficiency, studies of central cholinergic integrity revealed a developmental delay in choline acetyltransferase activity and of high-affinity [3H]-choline uptake in several brain structures. Subsequent studies of muscarinic cholinergic binding site distribution showed a widespread loss of M1 sites, consistent with cholinergic cell loss. These alterations are similar to those reported in Alzheimer's disease, suggesting that the severe cognitive dysfunction in congenital OTC deficiency may at least partly result from a muscarinic cholinergic lesion. Possible mechanisms involved in the pathogenesis of cholinergic cell loss in congenital OTC deficiency include ammonia-induced inhibition of pyruvate and alpha-oxoglutarate oxidation, resulting in decreased synthesis of acetyl CoA and a cerebral energy deficit, as well as NMDA receptor-mediated excitotoxicity. Treatment of spf mice with acetyl-L-carnitine (ALCAR) results in partial recovery of the developmental choline acetyltransferase deficit, suggesting a potential therapeutic benefit of ALCAR in congenital OTC deficiency. Other therapies currently used include ammonia-lowering strategies (using sodium benzoate or sodium phenylacetate) and, in severe cases, liver transplantation.
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PMID:Evidence for a central cholinergic deficit in congenital ornithine transcarbamylase deficiency. 977 87

Congenital ornithine transcarbamylase (OTC) deficiency in humans results in failure to thrive, hypotonia, seizures and mental retardation. Neuropathologic evaluation reveals significant cerebral cortical atrophy, delayed myelination and Alzheimer type II astrocytosis. Using an animal model of congenital OTC deficiency, the sparse fur (spf) mouse, studies reveal convincing evidence of a loss of forebrain cholinergic neurons in this condition. Evidence includes (i) reduced activities of the cholinergic nerve terminal enzyme choline acetyltransferase (ChAT), (ii) a 25% loss of ChAT immunostaining, (iii) reduced high affinity transport of [3H]choline by cortical synaptosomes and (iv) a selective reduction in densities of presynaptic muscarinic M2 binding sites, in spf mouse brain compared to controls. A partial correction of the cholinergic deficit was observed following treatment with acetyl-L-carnitine. Possible mechanisms responsible for cholinergic neuronal loss in congenital OTC deficiency include decreased synthesis of the ChAT substrate acetyl CoA, impaired cerebral energy metabolism and NMDA receptor-mediated excitotoxicity. Loss of forebrain cholinergic neurons is consistent with the severe cognitive impairment characteristic of congenital OTC deficiency.
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PMID:Evidence for forebrain cholinergic neuronal loss in congenital ornithine transcarbamylase deficiency. 1088 42


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