Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0917816 (mental retardation)
 15,867 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The development of the fetal central nervous system can be effected by drugs. In this paper we review the neurological consequences of intrauterine exposure to alcohol, cocaine, opiates and marijuana. Ethanol causes the fetal alcohol syndrome: mental retardation, intrauterine and postnatal growth retardation, and peculiar dysmorphic features. Is pathogenesis has been explained on the basis of maternal nutritional deficiencies or due to abnormalities in the conversion of ethanol to aldehyde, or abnormalities in the metabolism of prostaglandins or retinoic acid, the neurotransmitter systems, the neuronal excitotoxic activity, the development of the white matter, the production of gangliosides, and/or genetic regulation cell-cell adhesion. Cocaine has been related to congenital malformations, neurologic abnormalities during the neonatal period and psychomotor and cognitive development deficits. Characteristic dysmorphic features and a higher incidence of the sudden infant death syndrome (SIDS) have also been described. The following mechanisms have been implicated in the pathogenesis: vascular effects, superoxide formation, chelation of calcium ion channels, and abnormalities in the production of glycosphingolipids, the synthesis of DNA, the functioning of neurotransmitter systems, the neuronal growth and differentiation, the neuronal excitotoxic activity and/or the expression of early immediate genes. Opiates produce intrauterine and postnatal growth retardation, neonatal abstinence syndrome, and deficits of the psychomotor and cognitive development. They also increase the incidence of SIDS. The pathogenesis has been related to abnormalities in the sensitivity of the locus ceruleus, the functioning of the neurotransmitter systems, and/or the expression of early immediate genes. Marijuana has been associated with intrauterine growth retardation, dysmorphic features, and abnormalities of the behavior during the neonatal period, the psychomotor and cognitive development, and the sleep. The pathogenesis is thought to be due to an action upon specific receptors, or upon the neurotransmitter systems, and/or to an increase in the production of carbon monoxide. The best treatment of the syndrome of intrauterine exposure to drugs in the prophylaxis. The identification of emotional and drug addiction problems in the mother can avoid disastrous consequences. The care of these children is complex and requires a good pediatric follow-up and an early intervention program while the mother on the parents continue with the drug addiction therapy. The coordinations of all the necessary services with the active participation of social workers, physicians, educators and teachers is crucial for a successful treatment.
 ...
PMID:[Intrauterine exposure to drugs]. 920 93

Calcium is an important second messenger that affects metabolic and physiological activities of developing and mature neurons. It has been reported that electrical activity is abnormal in cultured hippocampal and DRG neurons from the trisomy 16 (Ts16) mouse, a model for Down syndrome (trisomy 21-Ts21 in human). Whole-cell voltage-clamp, radiolabeled ligand binding techniques and mRNA measurements were used to study the effect of Ts16 on voltage-dependent calcium currents in cultured fetal hippocampal neurons from the Ts16 mouse. In neither Ts16 nor control diploid neurons were low-voltage-activated calcium currents detected. However, a high-voltage-activated (HVA) calcium current was identified and shown to be dihydropyridine sensitive. The density of this HVA calcium current was 80% greater in Ts16 neurons than in control. This difference correlated with a 70% increase in binding of radiolabeled dihydropyridine, PN200-110, a marker of L-type calcium channels. However, mRNA levels encoding the alpha1C and alpha1D subunits were unchanged in the Ts16 neurons. In contrast, mRNA level of the myo-inositol transporter, the gene for which is located on mouse chromosome 16, was elevated in Ts16 neurons due to a gene-dosage effect. Therefore, it is likely that posttranscriptional regulation of dihydropyridine-sensitive voltage-dependent calcium channels is abnormal in Ts16. As dihydropyridine sensitive HVA Ca channels are implicated in heterosynaptic long-term depression and long-term potentiation, the differences reported here, if also present in the Down syndrome brain, may contribute to mental retardation in that disorder.
 ...
PMID:Increased expression of voltage-activated calcium channels in cultured hippocampal neurons from mouse trisomy 16, a model for Down syndrome. 960 27

Subcortical band heterotopia (SBH) and classical lissencephaly (LIS) result from deficient neuronal migration which causes mental retardation and epilepsy. A single LIS/SBH locus on Xq22.3-q24 was mapped by linkage analysis and physical mapping of the breakpoint in an X;2 translocation. A recently identified gene, doublecortin ( DCX ), is expressed in fetal brain and mutated in LIS/SBH patients. We have identified four novel missense mutations in the gene, one familial mutation with LIS in a male and SBH in the carrier females, one de novo mutation in an SBH female, and two mutations in sporadic SBH female patients. The DCX gene is found to be expressed exclusively at a very high level in the adult frontal lobe. We have also cloned the X-linked mouse doublecortin (Dcx) gene. It encodes isoforms of a highly hydrophilic 40 kDa protein, homologous to its human counterpart and containing several potential phosphorylation sites. Both human and mouse DCX proteins are homologous to a CNS protein containing a Ca2+/calmodulin kinase domain, suggesting that the DCX protein may belong to a novel class of intracellular proteins involved in neuronal migration through Ca2+-dependent signaling.
 ...
PMID:Human doublecortin (DCX) and the homologous gene in mouse encode a putative Ca2+-dependent signaling protein which is mutated in human X-linked neuronal migration defects. 966 76

Darier's disease (DD) is a rare, dominantly inherited disorder that affects the skin producing a variety of types of lesion. Close examination of lesional DD skin shows the presence of abnormal keratinization (epidermal differentiation) and acantholysis (loss of cohesion) of keratinocytes. A number of clinical studies have described the co-occurrence of various neurological and psychiatric symptoms with DD, including mood disorders, epilepsy, mental retardation and a slowly progressive encephalopathy. A single locus for DD has been mapped to chromosome 12q23-q24.1, and a variety of missense, nonsense, frameshift and splicing mutations in the ATP2A2 gene have been described recently in families with DD. This gene encodes the sarcoplasmic/endoplasmic reticulum calcium-pumping ATPase SERCA2, which has a central role in intra-cellular calcium signalling. In this study, we performed mutation analysis on ATP2A2 in 19 unrelated DD patients, of whom 10 had neuropsychiatric phenotypes. We identified and verified 17 novel mutations predicting conservative and non-conservative amino acid changes, potential premature translation terminations and potential altered splicing. Our findings confirm that mutations in ATP2A2 are associated with DD. In neuropsychiatric cases, there was a non-random clustering of mutations in the 3' end of the gene ( P = 0.01), and a predominance of the missense type (70% versus 38% in DD patients). This supports the hypothesis that the DD gene has pleiotropic effects in brain and that mutations in SERCA2 are implicated in the pathogenesis of neuropsychiatric disorders.
 ...
PMID:ATP2A2 mutations in Darier's disease and their relationship to neuropsychiatric phenotypes. 1044 25

A novel human gene, TRPC5, was cloned from the region of Xq23 that contains loci for nonsyndromic mental retardation (MRX47 and MRX35) and two genes, DCX and HPAK3, implicated in two X-linked disorders (LISX and MRX30). Within a single YAC, we have determined the order cen-HPAK3(5'-3')-DCX(3'-5')-DXS7012E-TRPC5(3'-5' )-ter. TRPC5 encodes a 974-residue novel human protein (111.5 kDa predicted mass) and displays 99% homology with mouse TRP5, (MGD-approved symbol Trrp5) a novel member of a family of receptor-activated Ca2+ channels. It contains eight transmembrane domains, including a putative pore region. A transcript larger than 9.5 kb is observed only in fetal and adult human brain, with a relatively higher level in the adult human cerebellum. We devised an efficient method, Incorporation PCR SSCP (IPS), for detection of gene alterations. Five single-nucleotide variations in the TRPC5 gene were identified in males with mental retardation. However, these were found to be polymorphic variants. Exclusive expression of the TRPC5 gene in developing and adult brain suggests a possible role during development and provides a candidate gene for instances of mental retardation and other developmental defects.
 ...
PMID:Molecular cloning and characterization of TRPC5 (HTRP5), the human homologue of a mouse brain receptor-activated capacitative Ca2+ entry channel. 1049 32

Calcium is an important second messenger in eukaryotic cells. Many of the effects of calcium are mediated via its interaction with calmodulin and the subsequent activation of Ca(2+)/calmodulin-dependent (CaM) kinases. CaM kinases are involved in a wide variety of cellular processes including muscle contraction, neurotransmitter release, cell cycle control, and transcriptional regulation. While CaMKII has been implicated in learning and memory, the biological role of the other multifunctional CaM kinases, CaMKI and CaMKIV, is largely unknown. In the course of a degenerate RT-PCR protein kinase screen, we identified a novel serine/threonine kinase, Pnck. In this report, we describe the cloning, chromosomal localization, and expression of Pnck, which encodes a 38-kDa protein kinase whose catalytic domain shares 45-70% identity with members of the CaM kinase family. The gene for Pnck localizes to mouse chromosome X, in a region of conserved synteny with human chromosome Xq28 that is associated with multiple distinct mental retardation syndromes. Pnck is upregulated during intermediate and late stages of murine fetal development with highest levels of expression in developing brain, bone, and gut. Pnck is also expressed in a tissue-specific manner in adult mice with highest levels of expression detected in brain, uterus, ovary, and testis. Interestingly, Pnck expression in these tissues is restricted to particular compartments and appears to be further restricted to subsets of cells within those compartments. The chromosomal localization of Pnck, along with its tissue-specific and restricted pattern of spatial expression during development, suggests that Pnck may be involved in a variety of developmental processes including development of the central nervous system.
 ...
PMID:Cloning, characterization, and chromosomal localization of Pnck, a Ca(2+)/calmodulin-dependent protein kinase. 1067 39

Duchenne muscular dystrophy (DMD) and the allelic disorder Becker muscular dystrophy (BMD) are common X-linked recessive neuromuscular disorders that are associated with a spectrum of genetically based developmental cognitive and behavioral disabilities. Seven promoters scattered throughout the huge DMD/BMD gene locus normally code for distinct isoforms of the gene product, dystrophin, that exhibit nervous system developmental, regional and cell-type specificity. Dystrophin is a complex plasmalemmal-cytoskeletal linker protein that possesses multiple functional domains, autosomal and X-linked homologs and associated binding proteins that form multiunit signaling complexes whose composition is unique to each cellular and developmental context. Through additional interactions with a variety of proteins of the extracellular matrix, plasma membrane, cytoskeleton and distinct intracellular compartments, brain dystrophin acquires the capability to participate in the modulatory actions of a large number of cellular signaling pathways. During neural development, dystrophin is expressed within the neural tube and selected areas of the embryonic and postnatal neuraxis, and may regulate distinct aspects of neurogenesis, neuronal migration and cellular differentiation. By contrast, in the mature brain, dystrophin is preferentially expressed by specific regional neuronal subpopulations within proximal somadendritic microdomains associated with synaptic terminal membranes. Increasing experimental evidence suggests that in adult life, dystrophin normally modulates synaptic terminal integrity, distinct forms of synaptic plasticity and regional cellular signal integration. At a systems level, dystrophin may regulate essential components of an integrated sensorimotor attentional network. Dystrophin deficiency in DMD/BMD patients and in the mdx mouse model appears to impair intracellular calcium homeostasis and to disrupt multiple protein-protein interactions that normally promote information transfer and signal integration from the extracellular environment to the nucleus within regulated microdomains. In DMD/BMD, the individual profiles of cognitive and behavioral deficits, mental retardation and other phenotypic variations appear to depend on complex profiles of transcriptional regulation associated with individual dystrophin mutations that result in the corresponding presence or absence of individual brain dystrophin isoforms that normally exhibit developmental, regional and cell-type-specific expression and functional regulation. This composite experimental model will allow fine-level mapping of cognitive-neurogenetic associations that encompass the interrelationships between molecular, cellular and systems levels of signal integration, and will further our understanding of complex gene-environmental interactions and the pathogenetic basis of developmental disorders associated with mental retardation.
 ...
PMID:Brain dystrophin, neurogenetics and mental retardation. 1075 78

Cerebral hypoxia in the fetus and newborn results in neonatal morbidity and mortality as well as long-term sequelae such as mental retardation, seizure disorders, and cerebral palsy. In the developing brain, determinants of susceptibility to hypoxia should include the lipid composition of the brain cell membrane, the rate of lipid peroxidation, the presence of antioxidant defenses, and the development and modulation of excitatory amino acid neurotransmitter receptors such as the N-methyl-D-aspartate (NMDA) receptor, the intracellular Ca2+, and the intranuclear Ca(2+)-dependent mechanisms. In addition to the developmental status of these cellular components, the response of these potential mechanisms to hypoxia determines the fate of the hypoxic brain cell in the developing brain. Using electron spin resonance spectroscopy of alpha-phenyl-N-tert-butyl-nitrone spin adducts, studies from our laboratory demonstrated that tissue hypoxia results in increased free radical generation in the cortex of fetal guinea pigs and newborn piglets. Pretreatment with MgSO4 significantly decreased the hypoxia-induced increase in free radical generation in the term fetal brain. We also showed that brain tissue hypoxia modifies the NMDA receptor ion-channel recognition and modulatory sites. Furthermore, a higher increase in NMDA receptor agonist-dependent Ca2+ in synaptosomes was demonstrated. The increase in intracellular Ca2+ may activate several enzymatic pathways such as phospholipase A2 and metabolism of archidonic acid by cyclooxygenase and lipoxygenase, conversion of xanthine dehydrogenase to xanthine oxidase by proteases, and activation of nitric oxide synthase. Using inhibitors of each of these enzymes such as cyclooxygenase (indomethacin), lipoxygenase (nordihydroguaiaretic acid), xanthine oxidase (allopurinol), and nitric oxide synthase (N-nitro-L-arginine), studies have shown that these enzyme reactions result in oxygen free radical generation, membrane peroxidation, and cell membrane dysfunction in the hypoxic brain. Specifically, generation of nitric oxide free radicals during hypoxia may lead to nitration and nitrosylation of specific membrane proteins and receptors, resulting in dysfunction of receptors and enzymes. We conclude that hypoxia-induced modification of the NMDA receptor leading to increased intracellular Ca2+ results in free radical generation and cell injury. We suggest that during hypoxia the increased intracellular Ca2+ may lead to increased intranuclear Ca2+ concentration and alter nuclear events including transcription of specific apoptotic genes and activation of endonucleases, resulting in programmed cell death.
 ...
PMID:Mechanisms of perinatal cerebral injury in fetus and newborn. 1081 2

The article presents data concerning pseudohypoparathyroidism (PH TP). It is an unusual disease, which is characterized by the resistance of bones and kidney to PTH, followed by hypocalcaemia, hyperphospha-taemia, glandulary hypertrophy and hypersecretion of PTH. Patients with PTHT clinically manifest tetany seizures, soft tissue calcifications and many congenital malformations. The disease has a genetic etiology, it is connected with chromosome X and more often found in women. Clinical symptoms may be different and depend on genetic defect or its selectivity with reference to the tissues. At present we can distinguish three types of PHPT and pseudo-pseudo-HPT. The disease usually appears in the infancy. Early diagnosis and vitamin D3 or calcium treatment seem to be the most important for patient's condition. Too late treatment threatens with brain calcification followed by neurological defects and mental retardation. The long-lasting effect of PTH in bones can lead to their destruction, if bone receptors are completely sensitive.
 ...
PMID:[Pseudohypoparathyroidism]. 1090 70

Disorders of neuronal migration in cerebral cortex are associated with neurological impairments, including mental retardation and epilepsy. Their causes and pathophysiology remain largely unknown, however. In patients with Zellweger disease, a lethal panperoxisomal disorder, and in mice lacking the Pxr1 import receptor for peroxisomal matrix proteins, the absence of peroxisomes leads to abnormal neuronal migration. Analysis of Pxr1-/- mice revealed that the migration defect was caused by altered N-methyl-D-aspartate (NMDA) glutamate receptor-mediated calcium mobilization. This NMDA receptor dysfunction was linked to a deficit in platelet-activating factor, a phenomenon related to peroxisome impairment. These findings confirm NMDA receptor involvement in neuronal migration and suggest a link between peroxisome metabolism and NMDA receptor efficacy.
 ...
PMID:Neuronal migration disorder in Zellweger mice is secondary to glutamate receptor dysfunction. 1097 40


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>