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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

Fragile X syndrome, an X-linked genetic disorder, is the third most common cause of mental retardation. The following is a case of a 6-year-old boy with fragile X syndrome and its characteristic cognitive and behavioral symptomatology, including attention deficit hyperactivity disorder. In addition, this child experienced initial insomnia and nocturnal enuresis, problems not previously reported with fragile X. Previous pharmacological treatment of the syndrome's behavioral difficulties and attention deficit has included stimulants, folic acid, and neuroleptics. This is the first report of the successful use of imipramine. Imipramine also improved the boy's insomnia and enuresis, whereas methylphenidate caused an overall worsening of his condition.
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PMID:Imipramine treatment of ADHD in a fragile X child. 193 2

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 two half-brothers with the FG syndrome which is an X-linked recessive multiple congenital anomalies/mental retardation (MCA/MR) syndrome. Both patients show postnatal short stature and an altogether characteristic face consisting of droopy appearance, macrocephaly, frontal upsweep, hypertelorism, full lower lip, retrognathia, and dysmorphic ears. Moreover, since early infancy both have a tendency towards constipation, their muscle tone is low and psychomotor development is moderately retarded. Minor expression of this syndrome in the patients' mother and her two mentally retarded brothers give additional support to the X-linked nature of the condition. On the basis of the pertinent literature, a concise description of this MCA/MR syndrome with variable expression is given. Diagnostic evaluation of dysmorphic male patients with psychomotor retardation should always consider the FG syndrome which has been known since 1974 but still is inadequately recognised in the German literature.
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PMID:[FG syndrome in 2 half brothers]. 196 Dec 7

X-linked recessive hydrocephalus (HSAS) occurs at a frequency of approximately 1 per 30,000 male births and consists of hydrocephalus, stenosis of the aqueduct of Sylvius, mental retardation, spastic paraparesis, and clasped thumbs. Prenatal diagnosis of affected males by ultrasonographic detection of hydrocephalus is unreliable because hydrocephalus may be absent antenatally. Furthermore, carrier detection in females is not possible because they are asymptomatic. Using four families segregating HSAS, we performed linkage analysis with a panel of X-linked probes that detect restriction fragment length polymorphisms. We report here that HSAS, in all tested families, is closely linked to marker loci mapping in Xq28 (DXS52, lod = 6.52 at theta of 0.03; F8, lod = 4.32 at theta of 0.00; DXS15, lod = 3.40 at theta of 0.00). These data assign HSAS to the gene-dense chromosomal band Xq28 and allow for both prenatal diagnosis and carrier detection by linkage analysis.
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PMID:Assignment of X-linked hydrocephalus to Xq28 by linkage analysis. 197 56

The most common genetic cause of mental retardation after Down's syndrome, the fragile X syndrome, is associated with the occurrence of a fragile site at Xq27.3. This X-linked disease is intriguing because transmission can occur through phenotypically normal males. Theories to explain this unusual phenomenon include genomic rearrangements and methylation changes associated with a local block of reactivation of the X chromosome. Using microdissected markers close to the fragile site, we have been able to test these hypotheses. We present evidence for the association of methylation with the expression of the disease. However, there is no simple relationship between the degree of methylation and either the level of expression of the fragile site or the severity of the clinical phenotype.
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PMID:Physical mapping across the fragile X: hypermethylation and clinical expression of the fragile X syndrome. 199 11

We have identified 39 X-linked conditions in which mental retardation seems to be the primary characteristic, although pathogenesis is unknown. These conditions can be subdivided into syndromal and non-syndromal, depending on the existence of a recognizable pattern of minor anomalies and/or malformations, or lack thereof. Seventeen genes have been regionally mapped onto the X chromosome. However, in 14 instances the data were derived from a single family and most lod scores were less than 3.0.
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PMID:XLMR genes: update 1990. 201 56

Photographs of normal and abnormal relatives with X-linked mental retardation (XLMR) and clinical data are combined in a Macintosh II computer system to provide an objective and versatile means of evaluating developmental abnormalities. The system includes a flatbed scanner for the entry of photographs and text, additional memory to enhance resolution of photographs, and several programs which facilitate searches for keywords. The primary advantages of the system include an easy interaction between descriptive words and photographs, and rapid comparison of whole faces and specific traits from many individuals. Information within families and between disorders can easily be compared in coded or uncoded fashion. Data from the 34 currently described syndromes emerging from the category of "non-specific XLMR" are being used to develop and test this approach. Neither standard photographs nor most computerized diagnostic systems permit this flexibility. Ultimately, this approach will provide a valuable diagnostic and teaching aid.
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PMID:Computerized approach to X-linked mental retardation syndromes. 201 57

We report on a 4 generation family of individuals with an X-linked form of mental retardation involving 9 affected males and 5 obligate carrier females. Key manifestations include severe mental retardation, early hypotonia with progression to spasticity and contractures, choreoathetosis, seizures, presence of a long, narrow face with coarse features, cystic enlargement of the fourth ventricle with cerebellar hypoplasia (Dandy-Walker malformation), and iron accumulation in the basal ganglia with neuroaxonal dystrophy similar to Hallervorden-Spatz disease. Of the 5 known heterozygotes, 3 are dull intellectually, and one of the 3 developed a "presenile dementia." At autopsy she had iron deposition and neuroaxonal dystrophy in the basal ganglia and atrophy of the cerebral cortex. Although the clinical findings among relatives are variable, we conclude that this is a distinct, previously unrecognized X-linked mental retardation syndrome.
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PMID:New X-linked mental retardation disorder with Dandy-Walker malformation, basal ganglia disease, and seizures. 201 58

We describe a family with two half-brothers affected with severe mental retardation. The phenotype in the affected individuals is characterized by apparent acromegaly, profound mental retardation, and hyperactivity. The mother has analogous but less severe facial anomalies and mild mental impairment. Screening for fra(X) (q) was negative in peripheral lymphocytes using methotrexate for fra(X) enhancement. The clinical findings in our patients are similar to those described by Fryns et al. [1986] in two patients with acquired lesions of the central nervous system. CT investigations in one of our patients showed areas of hyperdensity in the pontine region and a small subarachnoid cyst. The pedigree suggests X-linked inheritance. The association of apparent acromegaly, CNS anomalies, megalotestes, and mental retardation in this family supports the hypothesis that a distinct syndrome may exist with phenotype anomalies more severe than those characteristic for the Martin-Bell syndrome but without fragile X.
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PMID:Mental retardation, acromegalic face, and megalotestes in two half-brothers: a specific form of X-linked mental retardation without fra(X) (q)? 201 59


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