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 total of 162 Duchenne (DMD) patients and two girls with a DMD phenotype were analysed for deletions in the central region of the dystrophin gene in order to determine if there was a correlation between mental retardation (MR) and the pattern of deletion. Approximately 43% of the patients studied had deletions with two dystrophin cDNAs, cf23a and cf56a, and among 148 patients who were mentally assessed, 50% were mentally retarded. The average IQ in the group of patients with DNA deletions did not differ significantly from those patients with no detectable deletions. However, six unrelated DMD boys with MR showed an identical pattern of deletion. Our observations in the group of patients who had detected DNA deletions suggest that exon 52 of the dystrophin gene may be functionally significant in the manifestation of MR: 70% (19/27) of patients with a deletion of this exon were mentally retarded, whereas only 38% (15/39) of MR patients had deletions not involving exon 52. This difference was statistically significant.
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PMID:Apparent association of mental retardation and specific patterns of deletions screened with probes cf56a and cf23a in Duchenne muscular dystrophy. 187 22

A Hispanic girl with Lowe oculocerebrorenal syndrome (OCRL), an X-linked recessive condition characterized by cataracts, glaucoma, mental retardation, and proteinuria, is reported. A balanced X;20 chromosomal translocation with the X chromosome breakpoint at q26.1 was found with high-resolution trypsin-Giemsa banding. Somatic cell hybridization was used to separate the X chromosome derivative and the chromosome 20 derivative in order to position, with respect to the translocation breakpoint, several DNA loci that are linked to the Lowe syndrome locus (Xq24-q26). DXS10 and DXS53 were found to be distal to the breakpoint, whereas DXS37 and DXS42 were located proximal to it. These studies suggest that the OCRL locus lies in the region between these probes. The translocation chromosome originated from an unaffected male without a visible translocation, indicating that the most likely cause of OCRL in this patient is the de novo translocation that disrupted the OCRL locus.
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PMID:Lowe oculocerebrorenal syndrome in a female with a balanced X;20 translocation: mapping of the X chromosome breakpoint. 189 26

The gene for von Recklinghausen neurofibromatosis (NF1) is on proximal 17q; the location of the gene for achondroplasia (ACH) is unknown. We have begun a molecular analysis of a patient with mental retardation, NF1 and ACH, a clinical presentation suggestive of a contiguous gene syndrome. In addition, this individual has a 47,XYY chromosome constitution. To define a possible chromosome 17 deletion, we investigated the copy number of DNA sequences linked to NF1 with conventional and pulsed-field gel electrophoresis (PFGE). We found no evidence for a deletion on chromosome 17. These results make it unlikely that this patient harbors a single deletion in the NF1 region causing both NF1 and ACH and suggest different mechanisms for the de novo occurrence of 2 autosomal dominant disorders in this individual.
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PMID:Molecular analysis of a patient with neurofibromatosis 1 and achondroplasia. 190 91

Laser microdissection has been used to dissect material from the X-chromosome region involved in fragile-X-linked mental retardation. After dissection, single chromosome slices corresponding to this fragile site were subjected to DNA amplification using either a vector ligation method (to provide known anchor sequences) or primer oligonucleotides corresponding to the ubiquitous Alu sequences. Amplified material was then cloned or, alternately, used to screen a gridded cosmid library. Eight cosmid clones identified in this way were regionally mapped using a panel of hybrid cell lines and shown to originate from a narrow interval centered on the fragile X site. Two clones are included in the approximately 6-cM interval defined by probes RNI (DXS369, 5 cM proximal) and VK21 (DXS 296, 1-2 cM distal) and which includes the fragile site, and at least one clone contains sequences conserved across species suggestive of a gene. This method combines the focused approach of microdissection and the convenience of obtaining cosmid (rather than small-insert) clones; it may be useful for studies of other defined chromosomal regions.
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PMID:Laser microdissection of the fragile X region: identification of cosmid clones and of conserved sequences in this region. 191 12

The Fra(X) syndrome is the most common inherited cause of mental retardation. It is associated with an unusual form of X-linked inheritance where both men and women can be carriers. The "X-inactivation imprinting model" proposed by Laird et al currently offers one explanation of the unusual genetics. Recognition of clinical features and accurate cytogenetic diagnosis is important because of the prevalence of this disorder and the necessity and demand for genetic counseling. A combination of fra(X) cytogenetic studies and DNA-based linkage analysis for carrier detection and prenatal diagnosis is currently in use and is undergoing development and improvement.
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PMID:The fragile X syndrome--clinical overview. 194 6

We report on a family with three males with MASA syndrome (mental retardation, aphasia, shuffling gait, and adducted thumbs). One patient demonstrated spastic paraplegia and psychomotor retardation but no adducted thumbs. The described family underlines the clinical variability in MASA syndrome. DNA studies confirm linkage to DNA markers of the Xq28 region. Analysis of published cases with hereditary spastic paraplegia (HSP), where linkage studies have been carried out, emphasizes the clinical variability in MASA syndrome and other types of HSP, thus making a definite diagnosis in single cases often impossible.
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PMID:MASA syndrome: clinical variability and linkage analysis. 195 49

L-methylmalonyl-CoA mutase (MCM; E.C. 5,4,99,2) is the apoenzyme for catalyzing the isomerization of L-methylmalonyl-CoA to succinyl-CoA. Genetic deficiency of MCM leads to the accumulation of precursors and abnormal metabolites of L-methylmalonyl-CoA. This can be associated with fulminant metabolic acidosis, widespread secondary aberrations in systemic metabolic homeostasis, mental retardation, or even neonatal death. This disorder is termed methylmalonic acidemia (MMA). This report, describes the use of an authentic, full-length cloned human cDNA probe, MCM26, kindly provided by Dr. Fred Ledley, for Southern blot analysis of genomic DNA. The pattern of EcoRI, Sac I and Hind III restriction endonuclease sites is reported from 14 unrelated control individuals of Chinese background. A Southern blot by EcoRI to the MCM26b probe reveals invariant bands of 4.1, 3.8, and 2.2 kb respectively. By EcoRI to the MCM26c probe, 7.2 kb is invariant. By HindIII to the MCM26c probe, invariant bands are 4.8 and 2.7 kb respectively. By SacI to the MCMb probe, invariant bands are 17, 8.0, 6.0, 3.6 and 1.8 kb respectively, while the polymorphic band is at 5.6kb. When combined with more diverse samples and additional polymorphisms, this restriction fragment length polymorphism may be useful for genetic diagnostic and linkage studies of MCM in MMA.
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PMID:Restriction fragment length polymorphisms at the methylmalonyl CoA mutase locus in normal Chinese. 197 11

We studied 10 members of a 4 generation Missouri kindred with a dominant mental retardation syndrome with increasing severity in males. The 21 year-old propositus presented with severe mental retardation, microcephaly, asymmetric face, exotropia, hypogonadism, joint hypermobility, rocker bottom feet, and 10 low digital arches. Two brothers and a male cousin had similar features. The mother, sister, niece, maternal aunt, female cousin, and grandmother were examined and each had 8 to 10 low digital arches. Five of the women had exotropia and one had pes cavus feet. Chromosome analysis for fragile X in multiple relatives was normal. To determine the likelihood that this was an X-linked syndrome. DNA from relatives was hybridized to probes which detect 13 different loci spanning the X-chromosome. A peak LOD score of 2.78 at theta equal to 0.0 was calculated for the syndrome locus and DXYS1 (pDP34). The more distal Xq loci showed increasing recombination with the syndrome locus. These results are consistent with location for this syndrome near Xq21.31, the chromosomal locus for DXYSI.
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PMID:Unique X-linked mental retardation syndrome with fingertip arches and contractures linked to Xq21.31. 201 61

Linkage analysis was carried out in a large four-generation German family segregating for non-specific X-linked mental retardation. Affected males have moderate intellectual handicap. Speech delay, deviant behaviour, and hyperactivity have also been reported. Head circumference and testicular volumes are normal. Cytogenetic analysis failed to show evidence for fragile site or structural abnormality of the X chromosome. None of the obligatory carriers shows any clinical symptoms. Close linkage without recombination (lod scores 1.74 to 2.05) has been found between the disease locus (MRX1) and the polymorphic DNA loci DXS7 (Xp11.4-p11.3), MAOA (Xp11.3-p11.23), DXS255 (Xp11.22), and DXS159 (Xq12) suggesting that the gene responsible for the disease in this family maps in the pericentromeric region of the X chromosome. Linkage data obtained with the flanking marker loci OTC (Xp21.1) and DXS95 (Xq21.2-q21.3) also were compatible with this localization of the MRX1 gene. Close linkage to loci from Xp22, Xq22, Xq24-25, or Xq28 could be excluded.
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PMID:Gene for non-specific X-linked mental retardation maps in the pericentromeric region. 201 62

Diagnosis of carriers of the fragile-X mental retardation gene is hampered by the paucity of tightly linked DNA markers. Recently, 2 new DNA markers RN1 (DXS369) and U6.2 (DXS304) have become available. Both markers are tightly linked to the fragile-X locus, but their location relative to the fragile site was not known with certainty. We have tested these new markers in a multipoint linkage analysis of 26 fragile-X families typed for DXS105 as a proximal marker and DXS52 as a distal marker. Our results establish the order DXS105-DXS369-fra(X)-DXS304-DXS52, which is in agreement with physical mapping results.
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PMID:Multipoint linkage analysis of DXS369 and DXS304 in fragile X families. 201 75


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