Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0917816 (mental retardation)
 15,867 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
 ...
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.
 ...
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.
 ...
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.
 ...
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.
 ...
PMID:Allan-Herndon-Dudley syndrome: clinical and linkage studies on a second family. 160 31

The locus DXS250, which is linked to the Allan-Herndon type of X-linked mental retardation, maps between DXS3 and DXYS1 in a panel of 40 families established by the Centre d'Etude du Polymorphisme Humain, Paris.
 ...
PMID:Genetic linkage analysis places locus DXS250 between locus DXYS1 and locus DXS3 in Xq21.3. 161 8

The fragile X syndrome is the most common cause of familial mental retardation and is characterized by a fragile site at the end of the long arm of the X chromosome. The unusual genetics and cytogenetics of this X-linked condition make genetic counseling difficult. DNA studies were of limited value in genetic counseling, because the nearest polymorphic DNA loci had recombination fractions of 12% or more with the fragile X mutation, FRAXA. Five polymorphic loci have recently been described in this region of the X chromosome. The positions of these loci in relation to FRAXA were defined in a genetic linkage study of 112 affected families. The five loci--DXS369, DXS297, DXS296, IDS, and DXS304--had recombination fractions of 4% or less with FRAXA. The closest locus, DXS296, was distal to FRAXA and had a recombination fraction of 2%. The polymorphisms at these loci can be detected in DNA enzymatically digested with a limited number of restriction endonucleases. A strategy for DNA studies which is based on three restriction endonucleases and on five probes will detect one or more of these polymorphisms in 94% of women. This strategy greatly increases the utility of DNA studies in providing genetic advice to families with the fragile X syndrome.
 ...
PMID:Genetic mapping of new DNA probes at Xq27 defines a strategy for DNA studies in the fragile X syndrome. 167 6

The fragile-X syndrome is the most frequent inherited form of mental retardation, with an incidence of 1 in 1,500 males. It is characterized by the presence of a fragile site at Xq27.3 induced in vitro by folate deprivation or by inhibitors of deoxynucleotide synthesis. Its mode of inheritance is unusual for an X-linked trait, with incomplete penetrance in both males and females. Some phenotypically normal males transmit the mutation to all their daughters who rarely express any symptoms, but penetrance is high in sons and daughters of these carrier women. Genetic and physical mapping of the Xq27-q28 region has confirmed that the disease locus is located at or very near the fragile site. Hypotheses proposed to account for the abnormalities in the inheritance of the disease include sequence rearrangements by meiotic recombination or a mutation that affects reactivation of an inactive X chromosome during differentiation of female germ cells. To detect such rearrangements, or methylation changes that may reflect a locally inactive X chromosome, we used pulsed-field gel analysis of DNA from fragile-X patients with probes close to the fragile-X locus. The probe Do33 (DXS465) detected abnormal patterns in fragile-X patients, but not in normal controls or in non-expressing male transmitters.
 ...
PMID:Abnormal pattern detected in fragile-X patients by pulsed-field gel electrophoresis. 167 39

A mapping study was performed on a 3-generation Spanish family with X-linked syndromal mental retardation. Affected males have a typical facial appearance, ear malformations, abnormal growth of teeth, clinodactyly, dimpled skin at the lower back, and patellar luxation. In pneumoencephalography a marked subcortical cerebral atrophy was evident. In the linkage studies with polymorphic DNA markers, no recombination was found between the disease locus and the loci OTC and DXS148, both assigned to Xp21.1. One or more recombinants were observed between the disease locus and loci from the distal part of Xp and the pericentromeric region. Close linkage to loci of Xq has also been excluded. The analysis of multiple informative meioses suggests that the disease locus maps between DXS255 (Xp11.22) and DXS84 (Xp21.1) on Xp.
 ...
PMID:Gene localization in a family with X-linked syndromal mental retardation (Prieto syndrome). 167 97

We report on a large 5-generation family with "nonspecific" X-linked mental retardation. Nine living affected males have an IQ between 50 and 70 but have normal stature, facial appearance, and testicular volumes and no other abnormalities. Two obligate carrier females had borderline intellectual abilities and visual-psychomotor difficulties similar to those seen in affected males. Results of chromosome studies, including fragile X, were normal in males and females. Linkage analysis was undertaken, with 19 X-specific chromosomal restriction fragment length polymorphisms (RFLPs), giving a maximal LOD score of 1.60 at a 0.10 recombination fraction for F9, suggesting a localization to distal Xq for the mutant gene in this family.
 ...
PMID:Linkage analysis in a large family with nonspecific X-linked mental retardation. 167 98


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>