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)

Urine specimens from 1778 mentally retarded patients and 420 age and sex matched non-retarded controls selected from a general practice have been analysed for non-amino organic acids by a quantitative extraction and gas chromatographic method. The compounds were identified by combined gas chromatography and mass spectrometry. Approximately 5% of the patients had an abnormal organic aciduria. The frequency of abnormalities was slightly higher (about 7%) in a group of 248 severely subnormal children, but not in cases with a family history of mental retardation, retarded sibs, or whose parents were consanguineous. The most frequently observed abnormalities were phenylalanine metabolites in cases of phenylketonuria (about 1%), increased excretion of benzoic acid (about 1%), and increased excretion of 2-oxoglutaric acid with or without raised urinary citric-acid levels (about 1%). The biochemical and clinical significance of these findings is being further investigated.
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PMID:Abnormal organic acidurias in mentally retarded patients. 4 15

We describe three further children with the DOOR syndrome (deafness, onycho-osteodystrophy and mental retardation). A severe seizure disorder and characteristic facial appearance are part of the syndrome. Fourteen similar cases including the present patients are now on record. Autosomal recessive inheritance is likely. An increased level of 2-oxoglutarate in both plasma and urine has been found in our three patients. It is suggested there may be an inherited metabolic defect in this malformation syndrome.
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PMID:DOOR syndrome (deafness, onycho-osteodystrophy, and mental retardation): elevated plasma and urinary 2-oxoglutarate in three unrelated patients. 381 64

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

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

DOOR syndrome (deafness, onychodystrophy, osteodystrophy, and mental retardation) is a rarely described disorder with less than 35 reports in the literature. The hallmarks of the syndrome, represented in the DOOR acronym, include sensorineural hearing loss, hypoplastic or absent nails on the hands and feet, small or absent distal phalanges of the hands and feet, and mental retardation. The purpose of our communication is to report on an additional patient with DOOR syndrome, delineate common as well as less frequent manifestations of DOOR syndrome, bring attention to the under appreciated facial features in DOOR syndrome, document the natural history of this disorder, and propose a suggested workup of those suspected of DOOR syndrome. DOOR syndrome is associated with characteristic, coarse facial features with large nose with wide nasal bridge, bulbous tip and anteverted nares, a long prominent philtrum and downturned corners of the mouth. The natural history is one of a deteriorative course, with progressive neurological manifestations including sensorineural deafness, seizures from infancy, optic atrophy, and a peripheral polyneuropathy. The majority of patients with DOOR syndrome have elevated levels of 2-oxoglutarate in the urine and plasma. In this report, we present a newborn with manifestations consistent with DOOR syndrome and a progressive clinical course. A comprehensive literature review reveals 32 patients with DOOR syndrome. In conclusion, DOOR syndrome is a neurometabolic disorder with recognizable facial features and a progressive natural history.
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PMID:DOOR syndrome: clinical report, literature review and discussion of natural history. 1799 65

Mutations of human PHF8 cluster within its JmjC encoding exons and are linked to mental retardation (MR) and a cleft lip/palate phenotype. Sequence comparisons, employing structural insights, suggest that PHF8 contains the double stranded beta-helix fold and ferrous iron binding residues that are present in 2-oxoglutarate-dependent oxygenases. We report that recombinant PHF8 is an Fe(II) and 2-oxoglutarate-dependent N(epsilon)-methyl lysine demethylase, which acts on histone substrates. PHF8 is selective in vitro for N(epsilon)-di- and mono-methylated lysine residues and does not accept trimethyl substrates. Clinically observed mutations to the PHF8 gene cluster in exons encoding for the double stranded beta-helix fold and will therefore disrupt catalytic activity. The PHF8 missense mutation c.836C>T is associated with mild MR, mild dysmorphic features, and either unilateral or bilateral cleft lip and cleft palate in two male siblings. This mutant encodes a F279S variant of PHF8 that modifies a conserved hydrophobic region; assays with both peptides and intact histones reveal this variant to be catalytically inactive. The dependence of PHF8 activity on oxygen availability is interesting because the occurrence of fetal cleft lip has been demonstrated to increase with maternal hypoxia in mouse studies. Cleft lip and other congenital anomalies are also linked indirectly to maternal hypoxia in humans, including from maternal smoking and maternal anti-hypertensive treatment. Our results will enable further studies aimed at defining the molecular links between developmental changes in histone methylation status, congenital disorders and MR.
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PMID:PHF8, a gene associated with cleft lip/palate and mental retardation, encodes for an Nepsilon-dimethyl lysine demethylase. 1984 42

Crystallographic analysis of the catalytic domain of PHD finger protein 8 (PHF8), an N(epsilon)-methyl lysine histone demethylase associated with mental retardation and cleft lip/palate, reveals a double-stranded beta-helix fold with conserved Fe(II) and cosubstrate binding sites typical of the 2-oxoglutarate dependent oxygenases. The PHF8 active site is highly conserved with those of the FBXL10/11demethylases, which are also selective for the di-/mono-methylated lysine states, but differs from that of the JMJD2 demethylases which are selective for tri-/di-methylated states. The results rationalize the lack of activity for the clinically observed F279S PHF8 variant and they will help to identify inhibitors selective for specific N(epsilon)-methyl lysine demethylase subfamilies.
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PMID:Crystal structure of the PHF8 Jumonji domain, an Nepsilon-methyl lysine demethylase. 2006 92

Dynamic regulation of histone methylation/demethylation plays an important role during development. Mutations and truncations in human plant homeodomain (PHD) finger protein 8 (PHF8) are associated with X-linked mental retardation and facial anomalies, such as a long face, broad nasal tip, cleft lip/cleft palate and large hands, yet its molecular function and structural basis remain unclear. Here, we report the crystal structures of the catalytic core of PHF8 with or without alpha-ketoglutarate (alpha-KG) at high resolution. Biochemical and structural studies reveal that PHF8 is a novel histone demethylase specific for di- and mono-methylated histone H3 lysine 9 (H3K9me2/1), but not for H3K9me3. Our analyses also reveal how human PHF8 discriminates between methylation states and achieves sequence specificity for methylated H3K9. The in vitro demethylation assay also showed that the F279S mutant observed in clinical patients possesses no demethylation activity, suggesting that loss of enzymatic activity is crucial for pathogenesis of PHF8 patients. Taken together, these results will shed light on the molecular mechanism underlying PHF8-associated developmental and neurological diseases.
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PMID:Structural insights into a novel histone demethylase PHF8. 2010 Dec 66