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

We studied a mouse model of the haploinsufficiency form of Rubinstein-Taybi syndrome (RTS), an inheritable disorder caused by mutations in the gene encoding the CREB binding protein (CBP) and characterized by mental retardation and skeletal abnormalities. In these mice, chromatin acetylation, some forms of long-term memory, and the late phase of hippocampal long-term potentiation (L-LTP) were impaired. We ameliorated the L-LTP deficit in two ways: (1) by enhancing the expression of CREB-dependent genes, and (2) by inhibiting histone deacetyltransferase activity (HDAC), the molecular counterpart of the histone acetylation function of CBP. Inhibition of HDAC also reversed the memory defect observed in fear conditioning. These findings suggest that some of the cognitive and physiological deficits observed on RTS are not simply due to the reduction of CBP during development but may also result from the continued requirement throughout life for both the CREB co-activation and the histone acetylation function of CBP.
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PMID:Chromatin acetylation, memory, and LTP are impaired in CBP+/- mice: a model for the cognitive deficit in Rubinstein-Taybi syndrome and its amelioration. 1520 31

CREB-binding protein (CBP) is an important transcriptional cofactor for various intracellular signaling pathways, including Ca(2+)- and cAMP-mediated gene activation. The loss of one CBP allele causes the human Rubinstein-Taybi syndrome, which is characterized by mental retardation and other severe developmental defects. Deletion of both CBP alleles in the mouse leads to early embryonic lethality. To address the function of CBP in late embryogenesis and in adult physiology, a floxed CBP allele (CBP(fl)) was generated. Using the Cre/loxP recombination system, CBP function was disrupted in principal forebrain neurons by breeding with a transgenic CaMKIIalpha-Cre mouse line to obtain CBP(fl/fl;CaMKIIalphaCre) mice. These mice contain CBP(stop523) alleles specifically in principal forebrain neurons, presumably resulting in the production of a truncated CBP protein unable to interact with a number of transcription factors, including phosphorylated CREB.
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PMID:Generation of a conditional allele of the CBP gene in mouse. 1545 71

Rubinstein-Taybi syndrome is a rare genodermatosis with characteristic features that include downward sloping palphebral fissures, broad thumbs and halluces, and mental retardation. Dermatologic manifestations include capillary malformations, keloid formation, and pilomatricomas. Systemic features may involve the cardiac, audiologic, ophthalmologic, endocrine, neurologic, and respiratory systems. The syndrome is sporadic in nature and has been linked to microdeletion at 16p13.3 encoding CREB-binding protein gene (CREBBP).
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PMID:Rubinstein-Taybi syndrome (broad thumb-hallux syndrome). 1574 72

Rubinstein-Taybi syndrome (RTS; MIM# 180849) is a well-known malformation syndrome, characterized by broad thumbs and halluces, a characteristic facies, short stature, and mental retardation. RTS is accompanied by a variety of morbid complications, particularly of the skeleton. Based on the experience of five RTS patients with malformation of the craniovertebral junction, we draw attention to previously unrecognized life-threatening complications of RTS, including instability of C1-C2, os odontoideum, hypoplasia of the dens, and fusion of the cervical vertebrae. One patient developed severe cervical myelopathy. Malformation of the cervical spine may be a common syndromic constituent of RTS, to which special attention should be paid to prevent its neurologic sequelae.
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PMID:Congenital anomaly of cervical vertebrae is a major complication of Rubinstein-Taybi syndrome. 1583 59

Rubinstein-Taybi syndrome (RTS), also known as 'broad thumbs syndrome' or 'broad thumb-hallux syndrome', is a malformation syndrome characterized by the triad of broad thumbs or first toes, a peculiar facial expression called 'comical face' and mental retardation. Although various malformations are combined with the triad, polydactyly is rare. We treated a male patient with RTS complicated by postaxial polydactyly of the foot. His clinical course was different from typical patients with polydactyly, especially in the aspect of walking development. Osteoplasty-combined surgery, which was ideal for anatomical reconstruction, was performed on the patient at 2 years and 11 months of age. A 4-year follow-up period was required until there was an improvement of dysbasia.
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PMID:Rubinstein-Taybi syndrome (RTS) with postaxial polydactyly of the foot: 4-year follow-up until improvement of dysbasia. 1590 35

Rubinstein-Taybi syndrome (RSTS) is a distinct dominant disorder characterized by short stature, typical face, broad angulated thumbs and halluces, and mental retardation. The RSTS can be caused by chromosomal microdeletions and molecular mutations in the CREBBP gene; however, relatively few mutations have been reported to date. Here, we aimed to determine the rate of point mutations and other small molecular lesions in true RSTS and possible mild variants, by using genomic DNA sequencing. A consecutive series of patients including 17 patients from our previous study was investigated. We identified 19 causative mutations of CREBBP in a total of 45 patients representing three different diagnostic groups: (a) 17 mutations in 30 patients with unequivocal RSTS (detection rate 56.6%), (b) two mutations in eight patients with features suggestive of RSTS ("moderate or incomplete RSTS", detection rate 25%), and (c) no mutation in seven patients with undiagnosed syndromes and isolated features of RSTS. In general, the mutations were distributed without hot spots and most were unique; however, three recurrent mutations (R370X, R1664H, and N1978S) were identified. Furthermore, we detected 15 different intragenic polymorphisms, including two non-synonymous coding polymorphisms, L551I and Q2208H. We report not only the highest detection rate (56.6%) of CREBBP mutations in patients with RSTS to date, but also the second missense mutation (N1978S) in a patient with moderate or incomplete RSTS. Previous studies have identified cytogenetic deletions in the CREBBP gene in eight to 12% of patients and very recently, Roelfsema et al. reported EP300 gene mutations in three of 92 (3.3%) patients with either true RSTS or different syndromes resembling RSTS. Our 56.6% detection rate of molecular mutations in CREBBP in patients with unequivocal RSTS supports the new concept that RSTS is a genetically heterogeneous disorder and furthermore, indicates that RSTS may be caused by gene/s other than CREBBP in up to 30% of cases.
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PMID:DNA sequencing of CREBBP demonstrates mutations in 56% of patients with Rubinstein-Taybi syndrome (RSTS) and in another patient with incomplete RSTS. 1602 71

The Rubinstein-Taybi syndrome (RTS) is a rare but well-defined condition characterized by growth and mental retardation, broad thumb-hallux, and distinctive facial features. Ten unrelated Taiwanese children (6 boys and 4 girls) with clinical features suggestive of RTS were evaluated. The associated anomalies included cryptochidism (6/6 males), microcephaly (9/10), congenital heart diseases (8/10), pectus excavatum (5/10), low IGF-I level (4/10), strabismus/nystagmus (4/10), epilepsy (3/10), glaucoma (2/10), cleft palate (2/10), web neck (2/10), limb hypoplasia (2/10), sleep apnea (1/10), and vesico-ureteral reflux (1/10). All of them had normal thyroid function. High-resolution chromosome studies by both G- and R-banding were applied to detect any microscopic chromosomal deletion, particularly over the 16p13 region (responsible for RTS locus). A panel of five cosmids spanning the human cyclic AMP-responsive element binding (CREB) binding protein (CREBBP or CBP) gene in terms of RT100, RT102, RT191, RT203 and RT166 (Leiden, the Netherlands) were used for fluorescence in situ hybridization on the metaphases of those patients. Three cases showed whole or partial deletion of one copy of the CBP gene. Thus, the rate for detecting interstitial submicroscopic deletion of this region by FISH was about 30% in these RTS patients. The disease severity seemed to be correlated with size of the deletion.
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PMID:Rubinstein-Taybi syndrome: clinical and molecular cytogenetic studies. 1623 61

Rubinstein-Taybi syndrome (RTS) is a human genetic disorder characterized by mental retardation and physical abnormalities including broad thumbs, big and broad toes, short stature, and craniofacial anomalies. The oral manifestations include small oral opening, pouting lower lip, retro/micrognathia. and higher arched, narrow palate. The purpose of this case report was to demonstrate the complicated dental treatment of a 12-year-old, developmentally disabled girl, living with a foster family, who suffered from RTS, extensive caries, and very poor oral hygiene. The patient demonstrated total lack of cooperation. The dental treatment had been carried out under general anesthesia (GA). Possible problems during GA in such patients are described. Fiberoptic video-assisted bronchoscope was prepared for the GA in case of airway emergency and/or difficult intubation. The GA process was uneventful, despite the extensive treatment delivered to the patient. Prospects for future good oral and dental status in this patient are questionable because of her extreme lack of cooperation.
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PMID:Dental treatment of a child with Rubinstein-Taybi syndrome. 1643 38

Mental retardation (MR) is a developmental brain disorder characterized by impaired cognitive performance and adaptive skills that affects 1-2% of the population. During the last decade, a large number of genes have been cloned that cause MR upon mutation in humans. The causal role of these genes provides an excellent starting point to investigate the cellular, neurobiological and behavioral alterations and mechanisms responsible for the cognitive impairment in mentally retarded persons. However, studies on Down syndrome (DS) reveal that overexpression of a cluster of genes and various forms of MR that are caused by single-gene mutations, such as fragile X (FraX), Rett, Coffin-Lowry, Rubinstein-Taybi syndrome and non-syndromic forms of MR, causes similar phenotypes. In spite of the many differences in the manifestation of these forms of MR, evidence converges on the proposal that MR is primarily due to deficiencies in neuronal network connectivity in the major cognitive centers in the brain, which secondarily results in impaired information processing. Although MR has been largely regarded as a brain disorder that cannot be cured, our increased understanding of the abnormalities and mechanisms underlying MR may provide an avenue for the development of therapies for MR. In this review, we discuss the neurobiology underlying MR, with a focus on FraX and DS.
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PMID:Dendritic pathology in mental retardation: from molecular genetics to neurobiology. 1668

Rubinstein-Taybi syndrome (RSTS) is a well-known autosomal dominant mental retardation syndrome with typical facial and skeletal abnormalities. Previously, we have reported two patients presenting with RSTS and additional clinical features including failure to thrive, seizures, and intractable infections (Bartsch et al. in Eur J Hum Genet 7:748-756, 1999). Recently we identified a third patient with this condition, termed here severe RSTS, or chromosome 16p13.3 deletion syndrome. The three patients died in infancy, and all displayed a specific mutation, a chromosomal microdeletion including the 3'-end of the CREBBP gene. Using fluorescence in situ hybridization and closely spaced DNA probes, we characterized the deletion intervals in these patients and in three individuals with a deletion of CREBBP and typical RSTS. The deleted DNA segments were found to greatly vary in size, spanning from approximately 40 kb to >3 Mb. Four individuals, including the patients with severe RSTS, exhibited deletions containing gene/s in addition to CREBBP. The patients with severe RSTS all had deletions comprising telomeric neighbor genes of CREBBP, including DNASE1, a dominant gene encoding a nuclease that has been associated with systemic lupus erythematodes. Our findings suggest that severe RSTS is distinct from RSTS and represents a novel true contiguous gene syndrome (chromosome 16p13.3 deletion syndrome). Because of the risk of critical infections and high mortality rate, we recommend that the size of the deletion interval should be determined in CREBBP deletion-positive patients with RSTS, especially in young children. Further studies are needed to delineate the clinical spectrum of the new disorder and to clarify the role of DNASE1.
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PMID:Evidence for a new contiguous gene syndrome, the chromosome 16p13.3 deletion syndrome alias severe Rubinstein-Taybi syndrome. 1678 66


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