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)

We report the results of screening for molecular deletions in 164 boys with DMD and BMD and correlation of deletions with clinical features. A deletion was detected in 100 cases (61%) by Southern blot hybridization analysis with cDNA probes. Thirty-eight different deletions and two duplications were identified. All deletions except one (deletion of exons 48-53) found in males with DMD disrupted the translational reading frame of the gene; however, six deletions in boys with BMD were out of frame. The same deletion in different individuals was found to occur with or without mental impairment, and many different deletions were associated with mental retardation. We were able to ascertain a series of boys [from this study and a previous one (Hodgson S V, Hart K, Abbs S, et al. Correlation of clinical and deletion data in Duchenne and Becker muscular dystrophy. J Med Genet 1989; 26: 682-693)] without significant mental retardation who had deletions which, when combined, covered the whole region of the gene in which deletions are commonly found, and within which region individual deletions can be associated with mental retardation.
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PMID:Correlation of clinical and deletion data in Duchenne and Becker muscular dystrophy, with special reference to mental ability. 148 53

Cloned cDNA sequences representing exons from the Duchenne/Becker muscular dystrophy (DMD/BMD) gene were used for deletion screening in a population of 287 males males affected with DMD or BMD. The clinical phenotypes of affected boys were classified into three clinical severity groups based on the age at which ambulation was lost. Boys in group 1 had DMD, losing ambulation before their 13th birthday; those in group 2 had disease of intermediate severity, losing ambulation between the ages of 13 and 16 years; and boys in group 3 had BMD, being ambulant beyond 16 years. A fourth group consisted of patients too young to be classified. Clinical group allocation was made without previous knowledge of the DNA results. A gene deletion was found in 124 cases where the clinical severity group of the affected boy was known. The extent of the deletions was delineated using cDNA probes. There were 74 different deletions. Fifty-five of these were unique to individual patients, but the other 19 were found in at least two unrelated patients. The different clinical groups showed generally similar distributions of deletions, and the number of exon bands deleted (that is, deletion size) was independent of phenotype. Some specific deletion types, however, correlated with the clinical severity of the disease. Deletion of exons containing HindIII fragments 33 and 34 and 33 to 35 were associated with BMD and were not found in patients with DMD. Deletions 3 to 7 occurred in four patients with the intermediate phenotype and one patient with BMD. Other shared deletions were associated with DMD, although in four cases patients with disease of intermediate severity apparently shared the same deletion with boys with DMD. The range of phenotypes observed, and the overlap at the genetic level between severe and intermediate and mild and intermediate forms of dystrophy, emphasizes the essential continuity of the clinical spectrum of DMD/BMD. There were no characteristic deletions found in boys with mental retardation or short stature which differed from deletions in affected boys without these features.
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PMID:Correlation of clinical and deletion data in Duchenne and Becker muscular dystrophy. 258 68

We have studied 30 French patients with X-linked muscular dystrophy of the Duchenne (DMD) and Becker (BMD) types for intragenic deletions, using the cDNA probes of the DMD/BMD gene. Sixteen patients (53%) had molecular deletions in one or several of the 65 Hind III fragments containing exons detected with the DNA probes; in four deletion cases junction, fragments of altered size were seen. Fourteen (87%) of the deletions were detected using only two (1-2a and 8) and fifteen with 8+(2b-3) of the cDNA subclones. In our limited sample, BMD was caused by deletions in the 5' end of the gene, and in two instances of DMD, deletions of similar types resulted in diseases of similar severity. Of two patients with mental retardation, both had deletions comprised exons contained in probe 8, but other patients without mental retardation are also deleted with probe 8. We conclude that cDNA hybridization studies provide a powerful diagnostic tool in DMD and BMD families.
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PMID:Molecular deletion patterns in Duchenne muscular dystrophy patients. 261 Apr 87

Of the approximately 170 families with X-linked muscular dystrophy of the Duchenne (DMD) and Becker (BMD) type in Finland, we have studied 90 unrelated patients for intragenic deletions by using the cDNA probes described by Koenig et al. Forty-five patients (50%) had molecular deletions of one or several of the 65 exon-containing HindIII fragments. In six deletion cases junction fragments of altered size were seen. Thirty-eight (84%) of the 45 deletions were detected using only two (1-2a and 8) of the six cDNA subclones. Using a wheelchair age of 12 years to distinguish between DMD and BMD, we found that the proportions of patients with deletions were similar. Deletions were equally common in familial and sporadic disease. BMD was more commonly caused by deletions in the 5' end of the gene than was DMD. In at least three instances deletions of similar type resulted in diseases of similar severity. Of 14 patients with mental retardation seven had deletions; six of these comprised exons contained in probe 8. We conclude that cDNA hybridization studies provide a powerful diagnostic tool in DMD and BMD and that they promise to produce better insights into molecular-clinical correlations.
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PMID:Gene deletions in X-linked muscular dystrophy. 292 94

Approximately one-third of the mutations responsible for Duchenne muscular dytrophy (DMD) do not involve gross rearrangements of the dystrophin gene. Methods for intensive mutation screening have recently been applied to this immense gene, which resulted in the identification of a number of point mutations in DMD patients, mostly translation-terminating mutations. A number of data raised the possibility that the C-terminal region of dystrophin might be involved in some cases of mental retardation associated with DMD. Using single-strand conformation analysis of products amplified by polymerase chain reaction (PCR-SSCA) to screen the terminal domains of the dystrophin gene (exons 60-79) of 20 unrelated patients with DMD or BMD, we detected two novel point mutations in two mentally retarded DMD patients: a 1-bp deletion in exon 70 (10334delC) and a 5' splice donor site alteration in intron 69 (10294 + 1G-->T). Both mutations should result in a premature translation termination of dystrophin. The possible effects on the reading frame were analyzed by the study of reverse transcripts amplified from peripheral blood lymphocytes mRNA and by the protein truncation test.
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PMID:Protein truncation test: analysis of two novel point mutations at the carboxy-terminus of the human dystrophin gene associated with mental retardation. 758 96

Duchenne and Becker muscular dystrophies (DMD/BMD) are caused by mutations in the human dystrophin gene. About two-thirds of DMD/BMD patients exhibit gross rearrangements in the gene whereas the mutations in the remaining one third are thought to be point mutations or minor structural lesions. By means of various progressive PCR-based techniques hitherto a number of point mutations has been described that in most cases should cause premature translational termination. These data indicate a particular functional importance for the C-terminal region of dystrophin and consequently for its gene products Dp 71 and Dp 116. To screen for microheterogeneities in this gene region we applied PCR-SSCP analysis to exons 60-79 of twenty-six DMD/BMD patients without detectable deletions. The study identified seven point mutations and one intron polymorphism. Six point mutations, found in DMD patients, should cause premature translational termination. One point mutation, identified in a BMD patient, results in an amino acid exchange. Five of the DMD patients bearing a point mutation are mentally retarded suggesting that a disruption of the translational reading frame in the C-terminal region is associated with this clinical finding in DMD cases. Therefore our data raise the possibility, that Dp 71 and/or Dp 116, the C-terminal translational products of dystrophin, may be causally involved in cases of mental retardation that are associated with DMD.
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PMID:Point mutations at the carboxy terminus of the human dystrophin gene: implications for an association with mental retardation in DMD patients. 828 Nov 50

Duchenne and Becker muscular dystrophies (DMD and BMD, respectively) are the most common inherited muscular diseases and caused by mutations in the dystrophin gene. Half to two-thirds of DMD and BMD patients carry deletions (usually of several kilobases of genomic DNA). The clinical progression in DMD and BMD patients with deletions can be predicted in 92% of cases based on whether the deletion maintains or disrupts the translational reading frame (frame-shift hypothesis). However, some exceptional cases have been reported; BMD cases whose dystrophin gene exons 3 to 7 were deleted (out-of-frame), more severe case whose dystrophin gene deletion maintains reading frame but includes N-terminal region, and so on. Splicing mutation is one kind of mutations of dystrophin gene, and usually induced by small mutation of exon-intron boundary sequence. However, intraexonal small mutation also induces exon skipping, due to disruption of exon recognition sequence, which is intraexonal sequence and necessary for splicing of the upstream intron. For molecular diagnosis of DMD/BMD it is important to analyze not only in genomic DNA level, but also in mRNA, protein, and clinical levels. And the relationship between molecular abnormality and clinical phenotype should be examined, especially when extramuscular symptoms (heart failure and mental retardation) are prominent.
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PMID:[Molecular genetics and problems found in genetic diagnosis of Duchenne Becker muscular dystrophy]. 943 21

Duchenne/Becker muscular dystrophies (DMD/BMD) are the most common inherited muscular disease and caused by mutations in the dystrophin gene. A half to two-thirds of DMD and BMD patients carry deletions (usually of several kilobases of genomic DNA). The clinical progression in DMD and BMD patients with deletions can be predicted in 92% of cases based on whether the deletion maintains or disrupts the translational reading frame (frame-shift hypothesis). However, some exceptional cases have been reported in which some posttranscriptional modifications were suggested, such as alternative splicing and reinitiation of translation. Splicing mutation is one kind of mutations of dystrophin gene, and usually induced by a small mutation of exon-intron boundary sequence. However, intraexonal small mutation also induces exon skipping, due to disruption of an exon recognition sequence, which is an intraexonal sequence and necessary for splicing of the upstream intron. Carrier diagnosis is one of the important clinical application of genetic diagnosis. In the case of DMD/BMD with deletions of the dystrophin gene, carrier diagnosis is difficult because of the existence of normal X chromosome. In these cases a linkage analysis is useful, and in some cases non-carriers can be directly diagnosed on the basis of microsattelite polymorphism detected in deleted region of patient. For the molecular diagnosis of DMD/BMD it is important to analyze not only at the genomic DNA level, but also at the mRNA, protein, and clinical levels. And the relationship between the molecular abnormality and clinical phenotype should be examined, especially extramuscular symptoms such as heart failure and mental retardation.
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PMID:[Genetic diagnosis of Duchenne/Becker muscular dystrophy; clinical application and problems]. 954 79

The distal part of the human dystrophin gene is characterised by particular features and seems to play an important functional role. Additionally in recent years several data have implicated minor mutations in this gene region in some patients with mental retardation (MR). In order to screen for pathogenic mutations at the distal part of the human dystrophin gene we have used single-strand conformation analysis of products amplified by polymerase chain reaction (PCR-SSCA) in 35 unrelated male Greek DMD/BMD patients with no detectable deletions. Seven patients also had severe mental retardation. Direct sequencing of samples demonstrating a shift of SSCA mobility revealed six different and pathogenic minor changes, five in DMD and one in a BMD patient. Four of the mutations were found in DMD patients with severe MR. Three of these mutations were localised in exon 66, which presents an interesting similarity with part of the 3' end of the genome of eastern equine encephalomyelitis virus (EEEV). The present data from Greek DMD/BMD patients give further information about the phenotypic effects consequent on mutations in exons at the distal part of the human dystrophin gene.
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PMID:Screening for minor changes in the distal part of the human dystrophin gene in Greek DMD/BMD patients. 1019 1

The clinical and molecular features of 25 Duchenne (DMD), two intermediate (D/BMD) and three Becker (BMD) muscular dystrophy patients from 26 unrelated families were evaluated. Early psychomotor development was normal in patients with D/BMD and BMD. Learning to walk independently after 15 months of age was a risk sign of DMD in nine (36%) patients. Abnormality in crawling was seen in 13 (54%) patients with DMD. These boys demonstrated initial symptoms earlier than those who learned to crawl normally. Mental retardation was established in five (20%) patients with DMD. Deletions in the dystrophin gene were found in 11 families (48%). They were accumulated (9/11, 82%) in the distal region of the gene.
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PMID:Duchenne and Becker muscular dystrophies: an Estonian experience. 1039 46


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