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)

The observation of heritable fragile sites on human chromosomes prepared for lymphocyte cultures has been shown to depend on the type of tissue culture medium in which the lymphocytes are grown. The sites are observed at a much greater frequency when medium 199 is used than when RPMI 1640, Ham's F10, Eagle's (basal), and CMRL 1969 are used. One site on the X chromosome is of clinical significance in that it is a marker for X-linked mental retardation.
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PMID:Fragile sites on human chromosomes: demonstration of their dependence on the type of tissue culture medium. 87 51

Eight patients in three families had mental retardation, characteristic facies and hands, and skeletal changes; the clinical features suggested to us that they had a syndrome previously thought to represent two entities described by Lowry and associates and by Coffin and associates, respectively. New findings include skeletal, orodental, and dermatoglyphic abnormalities and histopathologic changes suggesting that the syndrome is a heritable disorder of connective tissue. Severe expression in males and transmission through mildly affected females suggest X-linked or sex-influenced autosomal dominant inheritance.
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PMID:The Coffin-Lowry syndrome: an inherited faciodigital mental retardation syndrome. 113 53

Two families are described with an X-linked form of mental retardation in whom the affected males were found to have bilateral enlargement of the testes. No conclusive evidence of any endocrinological disturbance was found.
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PMID:X-linked mental retardation associated with macro-orchidism. 124 Sep 71

A seven-generation pedigree of apparent X-linked, nonspecific mental retardation is reported. There are 19 known affected males who appear to have received the gene through normal mothers. Retardation, lack of fine motor coordination, hyperactivity and a speech defect are the characteristics of affected individuals studied.
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PMID:X-linked nonspecific mental retardation. Report of a large kindred. 124 70

Norrie disease is a human X-linked recessive disorder of unknown etiology characterized by congenital blindness, sensory neural deafness and mental retardation. This disease gene was previously linked to the DXS7 (L1.28) locus and the MAO genes in band Xp11.3. We report here fine physical mapping of the obligate region containing the Norrie disease gene (NDP) defined by a recombination and by the smallest submicroscopic chromosomal deletion associated with Norrie disease identified to date. Analysis, using in addition two overlapping YAC clones from this region, allowed orientation of the MAOA and MAOB genes in a 5'-3'-3'-5' configuration. A recombination event between a (GT)n polymorphism in intron 2 of the MAOB gene and the NDP locus, in a family previously reported to have a recombination between DXS7 and NDP, delineates a flanking marker telomeric to this disease gene. An anonymous DNA probe, dc12, present in one of the YACs and in a patient with a submicroscopic deletion which includes MAOA and MAOB but not L1.28, serves as a flanking marker centromeric to the disease gene. An Alu-PCR fragment from the right arm of the MAO YAC (YMAO.AluR) is not deleted in this patient and also delineates the centromeric extent of the obligate disease region. The apparent order of these loci is telomere ... DXS7-MAOA-MAOB-NDP-dc12-YMAO.AluR ... centromere. Together these data define the obligate region containing the NDP gene to a chromosomal segment less than 150 kb.
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PMID:The Norrie disease gene maps to a 150 kb region on chromosome Xp11.3. 130 Nov 61

Fragile X syndrome is the most frequent form of inherited mental retardation and segregates as an X-linked dominant with reduced penetrance. Recently, we have identified the FMR-1 gene at the fragile X locus. Two molecular differences of the FMR-1 gene have been found in fragile X patients: a size increase of an FMR-1 exon containing a CGG repeat and abnormal methylation of a CpG island 250 bp proximal to this repeat. Penetrant fragile X males who exhibit these changes typically show repression of FMR-1 transcription and the presumptive absence of FMR-1 protein is believed to contribute to the fragile X phenotype. It is unclear, however, if either or both molecular differences in FMR-1 gene is responsible for transcriptional silencing. We report here the prenatal diagnosis of a male fetus with fragile X syndrome by utilizing these molecular differences and show that while the expanded CGG-repeat mutation is observed in both the chorionic villi and fetus, the methylation of the CpG island is limited to the fetal DNA (as assessed by BssHII digestion). We further demonstrate that FMR-1 gene expression is repressed in the fetal tissue, as is characteristic of penetrant males, while the undermethylated chorionic villi expressed FMR-1. Since the genetic background of the tissues studied is identical, including the fragile X chromosome, these data indicate that the abnormal methylation of the FMR-1 CpG-island is responsible for the absence of FMR-1 transcription and suggests that the methylation may be acquired early in embryogenesis.
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PMID:DNA methylation represses FMR-1 transcription in fragile X syndrome. 130 13

Cognitive impairment occurs in one-third of patients with Duchenne muscular dystrophy, a lethal X-linked, recessive disease caused by mutations in the dystrophin gene which is expressed in both brain and muscle, the two transcripts having alternative first exons. Previous reports have indicated that the 'brain-type' dystrophin transcript predominates in brain. Using in situ hybridisation with antisense oligonucleotides, expression of four distinct mRNAs in specific brain areas is demonstrated here; the 14 kb muscle-type and brain-type transcripts were found to coexist in cortical and hippocampal neurons and two new transcripts have been identified in dentate gyrus and cerebellar Purkinje neurons, respectively. The latter has a novel first exon which was isolated and sequenced from mouse and human, and which would encode a protein with a different amino-terminus from the known muscle- and brain-type isoforms. Mapping in human located this exon in a large intron between the muscle-type promoter and second exon of the dystrophin gene. This finding of four alternative transcripts regulated by different promoters in brain reveals a new complexity to dystrophin expression that may have important insights for mental retardation mechanisms.
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PMID:Expression of four alternative dystrophin transcripts in brain regions regulated by different promoters. 130 51

X-Linked Mental Retardation constitutes an important pathologic entity in genetics. The overall significance, history and background of the concept of X-Linked mental retardation is reviewed with a special mention to the cases referenced under the term non-specific X-Linked mental retardation. The concept of lod-score has brought some improvement in the clinical delineation of the X-Linked mental retardation syndromes with some recent reports of suggestive linkage studies. The fragile-X syndrome is discussed with a special focus on reports of X-linked mental retardation with X chromosomal deletions or duplications. Linkage and molecular studies are reported viewing genetic approaches based on restriction fragment length polymorphisms. DNA probes spanning the length of the X and Y chromosomes which may prove critical to the development of diagnostic tests are referred. Computer assistance for a compilation of clinical findings in the X-linked mental retardation syndromes is specified as a diagnostic review and assistance program to check on the various entities. A joint collaborative investigation is reported to ascertain families with X-linked mental retardation in order to develop direct and linkage studies for the diagnosis of there disorders.
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PMID:[Various genetic aspects of X-linked mental retardation]. 134 94

Linkage analysis was performed in a family with nonspecific X-linked mental retardation (MRX). Affected individuals had no clinical characteristics other than mental retardation. Linkage was detected to the marker loci DXS477, DXS465, DXS52, DXS15 and F8C with maximum lod scores of 1.70, 1.32, 2.52, 1.70, and 1.09, respectively (theta = 0.0). The results strongly indicate that the gene for mental retardation in the family studied maps close to DXS52.
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PMID:Linkage to Xq28 in a family with nonspecific X-linked mental retardation. 136 58

The P-20 intragenic marker was used to test for restriction fragment length polymorphisms in unrelated Chinese patients with Duchenne or Becker muscular dystrophy or X-linked mental retardation. In addition to polymorphism at the 6.0/3.5 kb MspI allelic site, we found an independent and high frequency of polymorphism at the 2.2/1.8 kb site. This differs from results found with other populations.
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PMID:Significantly higher frequency of the MspI 2.2 kb allele of the Duchenne muscular dystrophy intragenic probe P-20 in the Chinese population. 138 93


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