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)

Trisomy 21 (Ts21) is the most common live-born human aneuploidy; it results in a constellation of features known as Down's syndrome (DS). Ts21 is the most frequent cause of congenital heart defects and the leading genetic cause of mental retardation. To investigate the gene dosage effects of an extra copy of human chromosome 21 (Chr 21) on various phenotypes, we used microcell-mediated chromosome transfer to create embryonic stem (ES) cells containing Chr 21. ES cell lines retaining Chr 21 as an independent chromosome were used to produce chimeric mice with a substantial contribution from Chr 21-containing cells. Fluorescence in situ hybridization and PCR-based DNA analysis revealed that Chr 21 was substationally intact but had sustained a small deletion. The freely segregating Chr 21 was lost during development in some tissues, resulting in a panel of chimeric mice with various mosaicism as regards retention of the Chr 21. These chimeric mice showed a high correlation between retention of Chr 21 in the brain and impairment in learning or emotional behavior by open-field, contextual fear conditioning and forced swim tests. Hypoplastic thymus and cardiac defects, i.e. double outlet right ventricle and riding aorta, were observed in a considerable number of chimeric mouse fetuses with a high contribution of Chr 21. These chimeric mice mimic a wide variety of phenotypic traits of DS, revealing the utility of mice containing Chr 21 as unique models for DS and for the identification of genes responsible for DS.
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PMID:Mice containing a human chromosome 21 model behavioral impairment and cardiac anomalies of Down's syndrome. 1137 9

Plasmolipin is a membrane protein and belongs to the tetraspan molecule (4TM) family, an expanding group of myelin proteins many of which could be linked to human hereditary demyelinating neuropathies. We have cloned and sequenced the mouse plasmolipin gene, revealing the common organization of the 4TM gene group with four exons and a large first intron. Western blot analysis with an antibody raised against the C-terminal intracellular part of the protein showed that plasmolipin is expressed not only in the nervous system and kidney, but also in a number of other tissues such as thymus, testis, lung, and thyroid gland. By means of radiation hybrid mapping and FISH analysis, we could localize the human plasmolipin gene to Chromosome 16q13 within the putative region of the Bardet-Biedl syndrome type 2 (BBS2) gene locus. BBS2 is a clinically and genetically heterogeneous group of disorders resulting in rod-cone dystrophy, obesity, postaxial polydactyly, renal dysfunction, and mental retardation, which were very recently associated with a novel gene designated BBS2. With respect to intrafamiliar variations in the manifestation of BBS, we suggest that plasmolipin might be either another candidate gene or a modifier of the BBS2 phenotype.
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PMID:Plasmolipin: genomic structure, chromosomal localization, protein expression pattern, and putative association with Bardet-Biedl syndrome. 1170 81

Down syndrome (DS) is the congenital birth defect responsible for the greatest number of individuals with mental retardation. It arises due to trisomy of human chromosome 21 (HSA21) or part thereof. To date there have been limited studies of HSA21 gene expression in trisomy 21 conceptuses. In this study we investigate the expression of the HSA21 antioxidant gene, Cu/Zn-superoxide dismutase-1 (SOD1) in various organs of control and DS aborted conceptuses. We show that SOD1 mRNA levels are elevated in DS brain, lung, heart and thymus. DS livers show decreased SOD1 mRNA expression compared with controls. Since non-HSA21 antioxidant genes are reported to be concomitantly upregulated in certain DS tissues, we examined the expression of glutathione peroxidase-1 (GPX1) in control and DS fetal organs. Interestingly, GPX1 expression was unchanged in the majority of DS organs and decreased in DS livers. We examined the SOD1 to GPX1 mRNA ratio in individual organs, as both enzymes form part of the body's defense against oxidative stress, and because a disproportionate increase of SOD1 to GPX1 results in noxious hydroxyl radical damage. All organs investigated show an approximately 2-fold increase in the SOD1 to GPX1 mRNA ratio. We propose that it is the altered antioxidant ratio that contributes to certain aspects of the DS phenotype.
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PMID:An altered antioxidant balance occurs in Down syndrome fetal organs: implications for the "gene dosage effect" hypothesis. 1506 40

X-linked cyclin-dependent kinase-like 5 (CDKL5 or STK9) has recently been implicated in atypical Rett and X-linked West syndromes, severe neurological disorders associated with mental retardation, loss of communication and motor skills and infantile spasms and seizures in predominantly females. Besides CDKL5, these disease phenotypes are also linked to mutations in the MECP2 and ARX genes. Here, we have expressed and characterized CDKL5 and its mutant forms. CDKL5 is a 118 kDa protein that is widely distributed in all tissues, with highest levels in brain, thymus and testes. Whole mount embryo staining reveals CDKL5 to be ubiquitous. Within cells, CDKL5 is localized primarily in the nucleus. Removal of the C-terminal domain increases CDKL5 expression, enhances autophosphorylation activity and causes perinuclear localization, indicating that the C-terminus regulates CDKL5 function. Although we detect MeCP2 but not ARX binding to CDKL5, our results suggest that neither of these proteins are direct substrates of the CDKL5 kinase. Finally, the CDKL5 mutations associated with the disease phenotype cause loss of kinase activity as assessed by autophosphorylation. These results suggest that inactivation of the CDKL5 kinase can lead to severe neurodevelopmental disorders.
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PMID:CDKL5/Stk9 kinase inactivation is associated with neuronal developmental disorders. 1633 Apr 82

22q11 deletion syndrome (22q11DS) is a chromosomal disorder that results in variable multisystem abnormalities, including conotruncal cardiac malformations, aplasia or hypoplasia of the thymus and/or parathyroid glands, immunodeficiency, dysmorphic facial features, and cleft palate and other nasopharyngeal and dental anomalies. Individuals with 22q11DS also exhibit cognitive and behavioral difficulties, including delayed motor and speech-language development, mental retardation, low academic achievement, impaired spatial reasoning, poor attentional and executive functioning, attention-deficit hyperactivity disorder, autism spectrum disorders, mood disorders, and/or schizophrenia spectrum disorders. Interventions should be designed based on the results of periodic developmental and neuropsychological assessments and psychiatric screening. Future research should focus on understanding deletion-related gene-environment interactions and their effects on developmental and behavioral outcomes, identifying neurodegenerative processes in 22q11DS, and developing preventive models of behavioral and psychopharmacologic treatment.
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PMID:A review of neurocognitive and behavioral profiles associated with 22q11 deletion syndrome: implications for clinical evaluation and treatment. 1738 27

22q11.2 microdeletion which involves DiGeorge syndrome, velo-cardiofacial syndrome and conotruncal anomaly face syndrome occurs as a result of a deletion in the short segment of the long arm of the 22th chromosome. Patients with this syndrome have a wide clinical spectrum including learning difficulty, dysmorphic face, cardiac anomalies, hypocalcemia, hypoparathyroidism, cleft palate, thymus anomalies, immune failure and speech and feeding problems. The number of clinical characteristics which have been reported to be related with this syndrome is higher than 180. All anomalies may not be present in all patients. In this article, a 12-year old female patient who was found to have 22q11.2 microdeletion with mild mental retardation and dysmorphic face and who presented to our hospital because of convulsion and a 13-year old male patient who was found to have 22q11.2 microdeletion with hypocalcemia, hypoparathyroidism, dysmorphic face and mental retardation and who presented to our hospital because of convulsion (it was learned from his history that he was being followed up in another center because of autism) were presented.
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PMID:22q11.2 microdeletion in two adolescent patients who presented with convulsion. 2607 35


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