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

Nomenclature guidelines are proposed for non-specific and for syndromal forms of X-linked mental retardation. Non-specific mental retardations (MRX) are given unique symbols for each family (MRX1, MRX2, MRX3 ...). Syndromal mental retardations (MRXS) which do not as yet have specific symbols are given unique interim symbols for each syndrome (MRXS1, MRXS2, MRXS3 ...). The prerequisite for assignment of serial MRX and MRXS gene symbols is a minimum lod score (or multipoint lod score) of +2 between the MR locus and one or more X chromosome markers. Prior approval of availability for proposed gene symbols must be obtained from the Nomenclature Committee of the Human Gene Mapping Workshops.
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PMID:Nomenclature guidelines for X-linked mental retardation. 160 16

Prenatal diagnosis was requested by an obligate carrier of a new syndrome of X-linked mental retardation. There was close linkage between the disease gene and the hypervariable VNTR marker DXS255 with a lod score of 4.82 at o = 0 (90% support interval 0.00-0.12). When the request for prenatal diagnosis was made, additional family members were examined, resulting in an amended lod score of 6.71 at o = 0.0 (90% support interval 0.00-0.09). There were no informative flanking markers at the time of the request for prenatal diagnosis; hence it proceeded by 2 point linkage analysis. The fetus was female with a carrier risk in the interval of 91-100%. Given the limitations of the mapping data available for this disorder at the time of the request, the options of accepting or rejecting this as a case for prenatal diagnosis were carefully considered. Whilst prenatal diagnosis based on fetal sexing would be sufficient to prevent the birth of an affected child, the magnitude of the known two-point lod score between DXS255 and the disease gene provided a means for diagnosis with an accuracy between 91 and 100%.
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PMID:Use of linkage data obtained in single families: prenatal diagnosis of a new X-linked mental retardation syndrome. 160 20

Here we describe the clinical and neurological findings in 2 brothers with MASA syndrome and the changes in phenotypic and neurological findings during the prepubertal period. MASA syndrome seems to be an X-linked mental retardation syndrome with progressively appearing manifestations and neurological signs, making clinical diagnosis before age 4 years difficult.
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PMID:MASA syndrome: delineation of the clinical spectrum at prepubertal age. 160 18

Up to now, we have identified 77 X-linked conditions in which mental retardation is the primary or a major component manifestation. These conditions were subdivided into 2 categories, designated respectively "X-linked mental retardation syndromes" and "Non-specific X-linked mental retardation". Forty genes have been regionally mapped onto the X chromosome. However, in several 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 1992. 160 15

Mental retardation unassociated with the Fragile X syndrome accounts for up to 60% of patients with X-linked mental retardation. In this investigation, we report on a family with mild non-specific X-linked mental retardation (MRX) without other apparent phenotypic abnormalities. Linkage analysis on 27 relatives using 18 polymorphic markers spanning the X-chromosome demonstrated close linkage to DXYS1 with a peak LOD score of 2.14 at a theta of 0. Numerous families with various types of MRX have now been studied by other investigators using molecular genetic techniques. In addition to the family described in this report, a number of these have demonstrated linkage to the DXYS1 locus. These data suggest that a gene for mental retardation may exist in the region of DXYS1. Alternatively, this area of the X-chromosome may harbor multiple different but closely linked genes which cause the various types of MRX.
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PMID:Linkage of nonspecific X-linked mental retardation to Xq21.31. 160 23

A previously unreported X-linked MCA/MR syndrome is described in 4 members of a large family. Phenotypic manifestations include mental retardation, microcephaly, failure to thrive, severe congenital hypotonia, characteristic face, hypogenitalism, pachygyria. This appears to be an X-linked dominant trait with decreased penetrance and expressivity in carrier females.
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PMID:New XLMR syndrome with characteristic face, hypogenitalism, congenital hypotonia and pachygyria. 160 25

We report on 4 generations in a family with 3 living males, 3 males who died in infancy, and 3 females with neurologic impairment and agenesis of the corpus callosum (ACC). Manifestations in the surviving males include severe acquired micrencephaly, mental retardation, limb contractures, scoliosis, tapered digits with hyperconvex nails, a characteristic face with large eyes, prominent supraorbital ridges, synophris, optic atrophy, broad alveolar ridges and seizures. Urologic anomalies include renal dysplasia, cryptorchidism, and hypospadias. Two affected females were less severely impaired and continued to be socially responsive as adults, but had spastic quadriplegia and seizures. One obligate heterozygote was retarded with emotional problems while another obligate carrier female and her daughter were clinically normal. Pedigree analysis suggested X-linked inheritance with variable expression in females. These findings are inconsistent with the well-described X-linked conditions with ACC including FG syndrome and Aicairdi syndrome. ACC has not been described in Coffin-Lowry syndrome, a condition with similar clinical findings, which also demonstrates marked variability of expression in carrier females. In order to assist in carrier determination, brain imaging studies and DNA linkage analysis of the affected relatives was performed. We found a spectrum of agenesis of the corpus callosum with the most severe manifestations in the most severely affected males. DNA analysis using a series of X-linked probes suggests linkage with a LOD score of 1.26 at theta = 0 to a region between p 11.3 and p 21.3.
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PMID:New X-linked syndrome with seizures, acquired micrencephaly, and agenesis of the corpus callosum. 846 65

A family in which 6 males have X-linked mental retardation has been studied with polymorphic DNA probes. The males differ from unaffected males only in impaired intellect and in smaller head size. The gene that causes mental retardation in the family appears to be located in band Xq21 on the basis of linkage with 3 markers: DXS250, DXS345 and DXS3 (theta max = 0.00; Zmax = 1.6). A multipoint lod score of 2.36 was obtain with no recombination relative to DXS326 in Xq21. This family is considered to have nonspecific X-linked mental retardation and has been given the designation MRX8.
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PMID:MRX8: an X-linked mental retardation condition with linkage to Xq21. 160 27

We report on a family with X-linked mental retardation (XLMR) and severe spastic paraplegia. Appearance is normal but there is severe involvement of the lower limbs (affected relatives never walked), with minimal involvement of the upper limbs and unusual MRI findings including macrogyria, white matter hypoplasia, lack of myelination and a markedly increased paramagnetic signal suggestive of iron deposition. Linkage studies documented possible linkage, with no recombination, between the disease locus and DXS424. A 7-point linkage analysis yielded a maximum LOD score of 1.9, (theta = 0.00) for three loci spanning Xq22-q25. The combination of the unusual clinical and MRI findings and the tentative localization to a region different than other XLMR syndromes with spastic paraplegia, provide good evidence that this is a new XLMR syndrome.
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PMID:Spastic paraplegia with iron deposits in the basal ganglia: a new X-linked mental retardation syndrome. 160 30

We restudied a family with X-linked mental retardation (XLMR) originally reported in abstract form by Davis et al. [1981]. All 8 living affected males were examined. Characteristics included severe mental retardation, spastic paraplegia, dysarthria, muscle wasting, scoliosis, broad shallow pectus excavatum, long face, large ears with minor modeling anomalies, foot deformities, joint contractures, and neck drop. Stature, OFC, testicular volume, high resolution chromosome and fragile X studies, and plasma amino acids were all normal. Their manifestations closely resemble those of a large family with XLMR originally reported by Allan et al. [1944] and restudied by Stevenson et al. [1990]. This condition has been termed the Allan-Herndon-Dudley syndrome (AHDS). As AHDS has been mapped to Xq21, mapping studies were undertaken to determine if this family maps to the same location. These studies demonstrate tight linkage to Xq21, with a maximum lod score of 2.88 obtained with probe pX65H7 (DXS72). Multipoint analysis located the mutant gene quite close to pX65H7 (multipoint Z = 4.14), slightly more proximal in Xq21 than was suggested by the data from the original AHDS family. It appears likely that this family is the second reported family with AHDS.
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PMID:Allan-Herndon-Dudley syndrome: clinical and linkage studies on a second family. 160 31


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