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 boy with mental retardation developed idiopathic cardiomyopathy and glycogen storage myopathy, but with normal lysosomal enzyme activities, consistent with a syndrome of lysosomal glycogen storage disease with normal acid maltase coined by Danon et al (1981). He was in good health except for WPW syndrome diagnosed at 7 years of age. He had heart murmur with abnormal ECG, elevated serum GOT, GPT, LDH, CK and aldolase levels. An echocardiogram showed obstructive hypertrophic cardiomyopathy. Lysosomal enzyme activities including acid alpha-glucosidase in fibroblasts were within normal limits. In the biopsied biceps brachii muscle, there was a mild variation in fiber size. An approximately 10 percent of myofibers had tiny vacuoles which contained periodic acid Schiff positive granules and were slightly high in acid phosphatase activity. The vacuoles were encircled by membranes with high neuron specific enolase (NSE) and acethylcholin-esterase (AchE) activities. On electron microscopy, numerous autophagic vacuoles scavenging glycogen granules were recognized as seen in acid maltase deficiency. Because the vacuolar membranes were high in NSE and AchE activities, lysosomal membrane formation from the cell membrane may be defective. When one has a patient with mild to moderate mental retardation, idiopathic hypertrophic cardiomyopathy and high serum CK level, muscle biopsy must be performed to rule out the present disorder.
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PMID:[A patient with lysosomal glycogen storage disease with normal acid maltase]. 839 37

Apoptosis is the mechanism by which cells are programmed to die under a wide range of physiological and developmental stimuli. Accumulating evidence indicates that enhanced apoptosis (programmed cell death) in Down syndrome (DS) may play a role in mental retardation and precocious neurodegeneration of the Alzheimer-type. In this regard, alteration of several apoptosis related proteins have been reported in adult DS brain. Fetal DS neurons exhibited increased reactive oxygen species leading to early apoptosis, however, expression of apoptosis related proteins in fetal DS, has never been considered. To address this issue, we investigated the expression of proteins involved in apoptosis including Fas (CD95, APO-1), caspase-3, Bcl-2 and annexins in the cerebral cortex of control and DS fetal brain by western blot and two dimensional electrophoresis. Here, we report that no detectable changes were obtained in fetal DS brain in the expression of Fas, caspase-3, Bcl-2 and Annexins (I, II, V, and VI) compared to controls. In parallel experiment, we also examined the expression of neuron specific enolase (NSE), a neuronal marker found to be decreased in adult DS brain, to see if there is any neuronal loss and no difference was observed between the two groups. Protein expression did not correlate with age. The unchanged levels of Fas, Bcl-2 and annexins together with unaltered caspase-3 expression, a predominant caspase that executes apoptosis in the developing nervous system, suggest that enhanced apoptosis may not be apparent in fetal DS brain as demonstrated for adult DS brain.
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PMID:Unaltered expression of Fas (CD95/APO-1), caspase-3, Bcl-2 and annexins in brains of fetal Down syndrome: evidence against increased apoptosis. 1177 40

Trisomy 21, Down Syndrome, is the most common genetic cause of human mental retardation and results from non-disjunction of chromosome 21. Several reports have been linking folate metabolism to DS and indeed, chromosome 21 even encodes for a specific folate carrier. The availability of brain tissue along with the advent of proteomics enabled us to identify and quantify C1-tetrahydrofolate synthase (THF-S), a key element in folate metabolism in brain along with other enzymes involved in C1-metabolism. Brains of controls and DS subjects at the 18th-19th week of gestation were homogenised and separated on 2 dimensional gel electrophoresis with subsequent in-gel digestion and mass spectrometrical identification and quantification with specific software. THF-S was represented by three spots, possibly representing isoforms or posttranslational modifications. Two spots were significantly, about twofold, increased in fetal DS brain: Controls [means +/- SD: (spot 1) 2.55 +/- 0.69; (spot 3) 1.39 +/- 0.86] vs. Down syndrome [means +/- SD: (spot 1) 4.25 +/- 1.63; (spot 3) 4.43 +/- 2.13]. These results were reproducible when THF-S levels were normalised versus the housekeeping protein actin and neuron specific enolase to compensate cell or neuronal loss. C1-metabolism related enzymes ribose-phosphate pyrophosphokinase I, inositol monophosphate dehydrogenase, guanidine monophosphate synthease and S-adenosylmethionine synthase, gamma form, were comparable between groups. Overexpression of this key enzyme in fetal DS brain at the early second trimester may indicate abnormal folate metabolism and may reflect folate deficiency. This may be of pathomechanistic relevance and thus extends and confirms the involvement of folate metabolism in trisomy 21.
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PMID:Overexpression of C1-tetrahydrofolate synthase in fetal Down syndrome brain. 1506 41

Down Syndrome (DS, trisomy 21) is the most common genetic cause of mental retardation. The completed sequencing of genes encoded on chromosome 21 provides excellent basic information, however the molecular mechanisms leading to the phenotype of DS remain to be elucidated. Although overexpression of chromosome 21 encoded genes has been documented information at the protein expression level is mandatory as it is the proteins that carry out function. We therefore decided to evaluated expression level of seven proteins whose genes are encoded on chromosome 21: DSCR4, DSCR5, DSCR6; KIR4.2, GIRK2, KCNE1 and KCNE2 in fetal cortex brain of DS and controls at the early second trimester of pregnancy by Western blotting. beta-actin and neuron specific enolase (NSE) were used to normalise cell loss and neuronal loss. DSCR5 (PIG-P), a component of glycosylphosphatidylinositol- N-acetylglucosaminyltransferase (GPI-GnT), was overexpressed about twofold, even when levels were normalised with NSE. DSCR6 was overexpressed in addition but when normalised versus NSE, levels were comparable to controls. DSCR4 was not detectable in fetal brain. Potassium channels KIR4.2 and GIRK2 were comparable between DS and controls, whereas KCNE1 and KCNE2 were not detectable. Quantification of these proteins encoded on chromosome 21 revealed that not all gene products of the DS critical region are overexpressed in DS brain early in life, indicating that the DS phenotype cannot be simply explained by the gene dosage effect hypothesis. Overexpression of PIG-P (DSCR5) may lead to or represent impaired glycosylphosphatidylinositol- N-acetylglucosaminyltransferase mediated posttranslational modifications and subsequent anchoring of proteins to the plasma membrane.
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PMID:Protein levels of genes encoded on chromosome 21 in fetal Down Syndrome brain (Part V): overexpression of phosphatidyl-inositol-glycan class P protein (DSCR5). 1522 5