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 5 9/12-year-old Mexican female with argininemia presented at 4 years of age with severe growth retardation, microcephaly, mental retardation, loss of ability to walk, spasticity and epileptiform electroencephalogram. At follow-up, blood ammonia was elevated only twice out of 30 determinations. Blood arginine was 544 to 1,074 mumol/l (normal 61 to 173); cerebrospinal fluid arginine was 88 mumol/l (normal 6 to 29); and urinary arginine, citruline and argininosuccinic acid were consistently elevated. Arginase activities in tissues from the propositus were 0.01 mU/mg hemoglobin in erythrocytes (normal 29.8 to 96.1); 9 mU/mg protein in liver (normal 1,522 to 5,491); and 5 mU/mg protein in stratum corneum (normal 2,856 to 7,556). The demonstration of arginase deficiency in liver and stratum corneum suggests a generalized deficiency and helps to explain the elevation of blood arginine. Therapeutic trials of orally administered lysine to enhance dibasic amino acid competition and of enzyme replacement using erythrocyte transfusion did not result in significantly decreased blood arginine or clinical improvement.
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PMID:Arginase deficiency in multiple tissues in argininemia. 62 88

A 21-month-old girl with physical and mental retardation is described. She excreted an increased amount of lysine in urine but no excessive quantities of arginine, ornithine, or cystine. Serum level of lysine was found to be low but the levels of the other amino acids were within normal limits. The endogenous renal clearance rates of amino acids showed a marked high value of lysine and normal values of the other dibasic amino acids. Oral loading test of amino acids revealed an imparied absorption of lysine and normal absorption of arginine, ornithine, and cystine in the intestine. These results indicate a specific defect in transport of lysine in the intestine as well as in the renal tubule.
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PMID:Lysine malabsorption syndrome: a new type of transport defect. 124 85

Glutaric aciduria is a disorcer of lysine, tryptophan, and hydroxylysine metabolism characterized by intermittent metabolic acidemia, dystonia, athetosis and mental retardation. It is due to a recessively inherited deficiency of glutaryl-CoA dehydrogeanse, the enzyme(s) which catalyze the dehydrogenation of glutaryl-CoA to glutaconyl-CoA and decarboxylation of the latter to crotonyl-CoA. Abnormal quantities of glutaric, beta-hydroxyglutaric, and glutaconic acids are found in the urine of these patients. The nature of the movement disorder prompted study of the effects of the abnormally excreted metabolites on brain glutamate decarboxylase, an enzyme implicated in the pathogenesis of Huntington's chorea. Glutamate decarboxylase activity was examined in rat and rabbit brain acetone powders, stabilized with pyridoxal phosphate and glutathione. Glutarate, beta-hydroxyglutarate, and glutaconate were competitive inhibitors of this emzyme, Ki values being 1.3 X 10(-3) mol/l, 2.5 X 10(-4) mol/l, respectively. This inhibition may explain the neurological accompaniments of this syndrome.
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PMID:Inhibition of brain glutamate decarboxylase by glutarate, glutaconate, and beta-hydroxyglutarate: explanation of the symptoms in glutaric aciduria? 124 44

An unusual association of Bardet-Biedl syndrome with cystinuria was described in one patient. A 21-year-old male was admitted to hospital because of renal failure, severe deterioration of visual acuity, polydactyly, brachydactyly, and mental retardation. Laboratory investigations revealed a serum creatinine of 292 mumol/L (3.3 mg/dL) and a GFR of 25 mL/min per 1.73 m2. Quantitative ion exchange chromatography demonstrated an increased urinary excretion rate of cystine, lysine, arginine, and ornithine. The ophthalmologic examination showed a severe atypical retinal dystrophy. Visual acuity was severely deteriorated and the patient could only count the examining physician's fingers. The patient had been previously evaluated at the age of 7 years for polyuria, polydipsia, and growth failure. His workup at that time demonstrated nephrogenic diabetes insipidus, normal GFR, and a urinary amino acid pattern consistent with the cystinuric phenotype. There was mental retardation notwithstanding the normal ophthalmologic examination. Intravenous pyelography showed calyceal clubbing, calyceal cysts, and lobulated renal outlines of the fetal type. The patient was evaluated again at the age of 13 years for deterioration of visual acuity and the ophthalmologic examination showed an atypical retinal dystrophy, with sparse pigmentation, central and peripheral atrophy, attenuated vessels, and marked optic disk pallor. To our knowledge the association of Bardet-Biedl syndrome with cystinuria has never been reported. It is unlikely that cystinuria may have contributed to the kidney damage. The possibility that mental retardation has been induced or aggravated by cystinuria cannot be excluded.
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PMID:Bardet-Biedl syndrome and cystinuria. 146 12

We report cystinuria and symptoms of cerebellar atrophy in a 45-year-old man. His parents were first cousins, and many members of his family had stones of urinary tract or gait impairment. Neurological examination disclosed cerebellar signs resembling those of spinocerebellar degeneration. Urinalysis disclosed high cystine, lysine, ornitine and arginine output. Cystine was 1153.8 micro mol/day (normal range, 22-170); lysine, 3443.9 (normal range, 44-1000); ornitine, 283.8 (normal range, 7-40); and arginine, 154.0 (normal range, 9-50). Neurological complications reported to be associated with cystinuria include mental retardation, muscular dystrophy, hypotonia and dwarfism, mongolism, paroxysmal dyskinesia, myopathy, migraine, spastic paraplegia, multiple sclerosis, subacute combined degeneration and cranial polyneuropathy. Cerebellar signs have been reported in only two cases, and to our knowledge, this is the first case of cystinuria with cerebellar atrophy ever reported. Some common metabolic errors may have caused both disorders, although they also may have developed independently.
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PMID:[Cystinuria with symptoms of cerebellar atrophy--a case report]. 189 74

In a male infant with macrocephaly and dystonic cerebral palsy glutaric aciduria type I was detected by analysis of urine for organic acids. Glutaric aciduria type I is an inherited metabolic disorder of organic acids due to a defect of glutaryl-CoA-dehydrogenase in the intermediate metabolic step of lysine and tryptophan degradation. In the urine glutaric acid is usually accompanied by 3-hydroxy-glutaric acid in abnormal quantities. The enzyme defect in our patient was proved in cultured fibroblasts. In the cerebral computer tomography marked atrophy of bilateral frontotemporal regions could be demonstrated. The amount of urinary glutarat excretion decreased after protein but especially after lysine and tryptophan restriction in the diet. The administration of carnitine improved carnitine levels in blood and urine. Although the progression of neurological impairment could be stopped, dystonia and dyskinesis remained nearly unaltered. In spite of severe motor retardation, recognition and vocalisation were established. In the two year old patient mental retardation is relatively mild comparing with motor retardation. The administration of 100 or 200 mg Riboflavin/day was stopped, as it did not alter clinical symptoms or excretion of glutarat. Baclofen, an analogue of gamma-amino-butyric acid, was orally given (2 mg/kg/day) and improved dystonia, but did not influence organic aciduria. The neurological manifestations may be due in part to inhibition of neuronal glutamat decarboxylase by glutaric acid with decreased gamma-amino-butyric acid biosynthesis. The characteristic clinical symptoms with macrocephaly and dystonia and the very typical pattern of organic acids in urine are a challenge for rapid diagnosis and therapy.
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PMID:[Macrocephaly and dystonic cerebral palsy in a child with type I glutaric aciduria]. 194 71

We describe the molecular characterization of two mutations responsible for galactosemia, an inherited disorder of galatose metabolism that causes jaundice, cataracts, and mental retardation in humans. The coding region of galactose-1-phosphate uridylyltransferase (GALT; UDPglucose:alpha-D-galactose-1-phosphate uridylyltransferase, EC 2.7.7.12) was amplified by the polymerase chain reaction from total cDNA of a classic galactosemic individual and was characterized by direct sequencing of the products. Two missense mutations were identified: (i) replacement of valine-44 by methionine and (ii) replacement of methionine-142 by lysine. These mutations led to a drastic reduction in GALT activity when individual mutant cDNAs were overexpressed in a mammalian cell system, although full-length protein is synthesized in this assay. The two galactosemia mutations account for 3 of the 15 galactosemia alleles analyzed. These results suggest that galactosemia is caused by a variety of mutations, which might be responsible for the observed clinical heterogeneity of this disorder. We also present the molecular characterization of two GALT polymorphisms: (i) replacement of leucine-62 by methionine and (ii) replacement of asparagine-314 by aspartate. It appears that galactosemia mutations tend to occur in regions that are highly conserved throughout evolution while the polymorphisms change variable residues.
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PMID:Molecular basis of galactosemia: mutations and polymorphisms in the gene encoding human galactose-1-phosphate uridylyltransferase. 201 74

X-linked hydrocephalus is a genetic form of hydrocephalus that frequently occurs in females. It is characterized by ventricular dilatation, mental retardation, deformity of the thumb and spastic paraparesis. Recently, 23 different mutations of the gene for the neural cell adhesion molecule, L1CAM, located at chromosome region Xq28, have been reported, 16 of which were detected in families with X-linked hydrocephalus. We sequenced the coding region of the L1CAM gene of patients from two different families with X-linked hydrocephalus and found a novel mutation at nucleotide residue 1963 in one family. This mutation from adenine to guanine results in an amino acid change from lysine to glutamic acid at residue 655 of the L1CAM protein, which belongs to the fibronectin type III domain. We report another method of the rapid identification of the mutation based on the polymerase chain reaction. This mutation was not detected among 70 X chromosomes from a healthy population. Ours is the first report demonstrating this gene mutation in X-linked hydrocephalus in an Asian population. Our findings further emphasize the evolving genotypic heterogeneity in X-linked hydrocephalus.
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PMID:A new mutation of the L1CAM gene in an X-linked hydrocephalus family. 911 41

A human disorder caused by mutation in nonmuscle actin has not been reported. We report here a variant of nonmuscle actin in a female patient with recurrent infections, photosensitivity, and mental retardation. She also had abnormalities in neutrophil chemotaxis, superoxide production, and membrane potential response. Two-dimensional PAGE analysis of proteins from neutrophils and other cell types from this patient demonstrated a unique protein spot migrating at 42 kDa with pI shifted slightly to neutral relative to normal beta- and gamma-actin. Digestion peptide mapping and Western blotting showed this spot to be an abnormal actin. A full-length cDNA library was constructed by using mRNA from patient's cells and cDNA encoding the mutant beta-actin molecule was identified by an in vitro translation method. Sequencing of the clones demonstrated a G-1174 to A substitution, predicting a glutamic acid-364 to lysine substitution in beta-actin and eliminating a HinfI DNase restriction site found in normal beta-actin sequence. By HinfI digestion and by sequencing, the mutation in one allele of patient's genomic DNA was confirmed. Though no defect in cell-free polymerization of actin was detected, this defect lies in a domain important for binding to profilin and other actin-regulatory molecules. In fact, the mutant actin bound to profilin less efficiently than normal actin did. Heterozygous expression of mutant beta-actin in neutrophils and other cells of this patient may act in a dominant-negative fashion to adversely affect cellular activities dependent on the function of nonmuscle actin.
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PMID:A heterozygous mutation of beta-actin associated with neutrophil dysfunction and recurrent infection. 1041 37

Lysinuric protein intolerance (LPI) results in low serum L-arginine, hyperammonemia, mental retardation, thrombocytopenia, and an increased frequency of bowel movements. Our objective was to evaluate the effects of low serum L-arginine, the essential substrate for reactions catalyzed by nitric oxide synthetase (NOS), on the serum nitric oxide (NO) level and coagulation activity in a patient with LPI. A 37-year-old Japanese man who presented with abdominal pain and subnormal fasting levels of serum L-arginine and L-lysine was found to have LPI. The result of oral administration of diamino acids was an increased in urine and a decrease in serum, thus confirming the diagnosis. A decrease in the platelet count and an increase in the plasma levels of thrombin-antithrombin III complex (TAT) and fibrin degradation products (FDPs) indicated the presence of subclinical intravascular coagulation. Serum levels of NO derivatives and L-arginine were determined after intravenous administration of L-arginine. The effects of intravenous L-arginine or transdermal nitroglycerin on the plasma level of TAT were also investigated. Serum levels of NO derivatives were significantly reduced in the LPI patient versus the healthy control group (n = 5). Intravenous administration of L-arginine increased the serum level of NO derivatives and the platelet count and reduced plasma TAT and FDP levels. The plasma level of TAT was also reduced by transdermal nitroglycerin. A decrease in the serum level of L-arginine in patients with LPI appears to result in a decrease in NO production. The improvement in plasma TAT levels produced by administration of intravenous L-arginine or transdermal nitroglycerin suggests that intravascular coagulation is exacerbated by the decrease of NO production in patients with LPI.
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PMID:Reduced nitric oxide production by L-arginine deficiency in lysinuric protein intolerance exacerbates intravascular coagulation. 1048 53


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