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Query: UMLS:C0917816 (mental retardation)
 15,867 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This is a presentation and discussion of clinical and laboratory data obtained on 13 girls with Rett syndrome, a progressive neurological disorder. The condition is thought to be far more prevalent than earlier reported. Family history in one patient showed presence of abnormal hand movements, increasing spasticity and psychomotor retardation in a paternal great grandaunt who died at 7 years. In the absence of chromosomal or biochemical markers, the characteristic disorder of hand movements can be used to distinguish this entity from other mental retardation, cerebral palsy and autism conditions. This report addresses the uniformity of clinical expression and highlights the differences between autism and Rett syndrome. Precocious puberty and respiratory alkalosis were not found in our patients. Feeding disorders were commonly present, and are often difficult to manage. The importance of diagnosis is emphasized as it influences long term management.
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PMID:Rett syndrome: studies of 13 affected girls. 308 8

A Case of Rett syndrome in a 20-year old female patient in a mental retardation institution is described. Clinically and according to the case history she is very typical for the syndrome, and the different stages, the etiological theories and some efforts in order to find etiological factors are surveyed.
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PMID:Rett syndrome. 343 61

Two sporadic cases of tuberous sclerosis presented with flexion spasms in a male and early intractable seizures evolving into a Lennox-Gastaut syndrome in a female. Early hypotonia and lack of substantial motor development are key features of the Rett syndrome, more easily overlooked than hand-wringing. Clumsy self-feeding and immature ambulation were the highest achievements in the second case now aged 36 years. Immaturity rather than degeneration, dementia, or assumed tissue destruction, is the capital feature of many disorders of early brain development leading to profound motor as well as mental retardation. Studying unusual clinical combinations is more likely to shed light on the underlying etiology than focusing on procrustean syndrome definitions.
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PMID:Rett syndrome associated with tuberous sclerosis in a male and in a female: evidence for arrested motor and mental development. 751 Sep 33

A high prevalence of psychiatric illness exists in persons with mental retardation. Among children with mild to moderate retardation, psychiatric illnesses resemble those seen in the general population. Major affective disorders, ADHD, and conduct disorder are common and respond to the same interventions used in children without mental retardation. Persons with severe to profound retardation are more likely to engage in stereotypies and self-injurious behaviors. In addition, certain specific syndromes associated with mental retardation present with particular neurocognitive, behavioral, and psychiatric profiles. Common examples are fetal alcohol syndrome, Down syndrome, fragile X syndrome, and Rett syndrome. Specific challenges exist for pediatricians who diagnose and treat patients with mental retardation and psychiatric illness. The child's impaired ability to communicate his or her thoughts and feelings with words makes clinical history taking difficult. The clinician must frequently rely on the observation of family members and teachers. An understanding of developmental profiles and interpersonal, peer, and family dynamics is important. Specific behaviors must be targeted and realistic objectives set in treatment planning, which may include psychotherapy, medication, behavior management techniques, and rehabilitation therapy.
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PMID:Dual diagnoses. Psychiatric disorders in developmental disabilities. 768 22

The Rett syndrome (RS) is a neurological disorder associated with severe mental deficiency and neurological manifestations of cortical and extrapyramidal dysfunction. The present report is (1) a postmortem brain study that compares the levels of choline acetyltransferase (ChAT) activity and the binding density of selected neurotransmitter receptors in four cases of RS and five normal controls of similar age and (2) a study of cerebrospinal fluid (CSF) concentrations of the endogenous tridecapeptide neurotensin in 12 RS patients and 8 controls of similar age. The level of ChAT activity was lower in many cortical and subcortical regions in the RS brains as compared to control levels. The number of NMDA, AMPA, mu opioid and neurotensin binding sites, as well as CSF concentrations of neurotensin, did not differ significantly from control levels. The results suggest that changes in specific neurotransmitter systems, particularly cholinergic neurons, in the thalamus, cerebellum and basal ganglia may underlie the progressive deterioration in motor and cognitive function characteristic of this disorder.
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PMID:Neurochemical alterations in Rett syndrome. 840 77

The presence of metatarsal and metacarpal abnormalities in some individuals has raised the possibility that Rett syndrome is, in fact, a multiple congenital abnormalities/mental retardation (MCA/MR) syndrome. We have conducted radiological examination of 17 cases of Rett syndrome in Western Australia. Short fourth and/or fifth metatarsals were identified in 65% of cases and short fourth and/or fifth metacarpals in 57%. Metatarsal (P = 0.045) and metacarpal (P = 0.006) shortness were significantly more common in girls 14 years or older. Negative ulnar variance (found in 79% of cases) appeared to be independent of age. Reduced bone density in the hands was found in 86% of cases. A nationwide study using the Australian Rett Syndrome Database is planned to follow up these findings and compare them with findings from a control group. The confirmation of these abnormalities in a high proportion of cases may provide morphologic markers to assist in the diagnosis of Rett syndrome and perhaps provide a further avenue of research into the pathogenesis of this disorder.
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PMID:Skeletal abnormalities in Rett syndrome: increasing evidence for dysmorphogenetic defects. 853 32

A 23-year-old pregnant woman was referred to the Genetics Department for genetic counselling and possible prenatal diagnosis because of unexplained mental retardation in a paternal uncle. Family history revealed that her father had two mentally retarded sisters well as a brother with mental retardation and a normal sister. This normal sister had two normal sons, on normal daughter and one mentally retarded daughter. The normal daughter had one daughter, who has been referred to the pediatric department because of mental retardation two months earlier; Rett syndrome was diagnosed as this girl had the classical symptoms of this syndrome. The paternal uncle of the consultant was examined. H head typical features of fragile X syndrome. Therefore cytogenetic and molecular studies were undertaken in this family. Fragile X syndrome was diagnosed in the girl with Rett syndrome by the presence of the classical FMR-1 mutation and confirmed by cytogenetic studies, which revealed 12% fragile X positive cells.
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PMID:Rett-like syndrome in fragile X syndrome. 858 47

M6 is a neuronal membrane glycoprotein that may have an important role in neural development. This molecule was initially defined by a monoclonal antibody that affected the survival of cultured cerebellar neurons and the outgrowth of neurites. The nature of the antigen was discovered by expression cDNA cloning using this monoclonal antibody. Two distinct murine M6 cDNAs (designated M6a and M6b) whose deduced amino acid sequences were remarkably similar to that of the myelin proteolipid protein were previously isolated. We have isolated partial human cDNA and genomic clones encoding M6a and M6b and have characterized them by restriction mapping, Southern hybridization with cDNA probes, and sequence analysis. We have localized these genes within the human genome by FISH (fluorescence in situ hybridization). The human M6a gene is located at 4q34, and the M6b gene is located at Xp22.2. A number of human neurological disorders have been mapped to the Xp22 region, including Aicardi syndrome (MIM 304050), Rett syndrome (MIM 312750), X-linked Charcot-Marie-Tooth neuropathy (MIM 302801), and X-linked mental retardation syndromes (MRX1, MIM 309530). This raises the possibility that a defect in the M6b gene is responsible for one of these neurological disorders.
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PMID:Chromosomal mapping of the human M6 genes. 866 Oct 15

Cyclooxygenase or prostaglandin endoperoxide H synthase-2 (PGHS-2) is the first enzyme in the prostanoid biosynthetic pathways and, in brain, it is regulated as an immediate-early gene (IEG). PGHS-2 mRNA and protein are rapidly induced by physiological synaptic activity, and high basal expression in cerebral cortex appears to be maintained by the natural synaptic activity. In contrast to other IEGs, PGHS-2 is a dendritic protein that is enriched in dendritic spines and is, therefore, likely to play a direct role in synaptic physiology. Consistent with a signaling function in mature dendritic spines, PGHS-2 expression is strongly regulated during normal postnatal development in the rat, with peak expression during the third and fourth weeks. Here we use immunocytochemical approaches to compare the developmental expression of PGHS-2 in rat neocortex with that of other well characterized markers of dendritic maturation. PGHS-2 immunoreactivity (ir) follows histogenetic gradients and expression in secondary or more distal dendrites postdates that of even the most delayed dendritic proteins. This developmental pattern parallels the critical period for somatosensory and visual cortex development. Accordingly, PGHS-2-ir may be a useful marker of the final activity-dependent stages of cortical development. Consistent with the potential histochemical utility, we demonstrate that the normal laminar pattern of PGHS-2-ir in human cortex is altered in patients with Rett syndrome, a form of mental retardation with known alterations of dendritic maturation. Further studies of the developmental expression of PGHS-2 in human cortical development may permit analyses of dendritic abnormalities, in syndromes associated with disturbances of activity-dependent development, as well as provide an anatomic basis for understanding the role of prostaglandin signaling in cortical development.
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PMID:Cyclooxygenase-2 expression during rat neocortical development and in Rett syndrome. 907 87

Rett syndrome (RS) is a progressive disorder that is predominant in females. It is associated with cortical atrophy, stereotyped hand movements mimicking hand-washing, severe mental deficiency, and cortical and extrapyramidal dysfunction. The cause of RS is unknown; no consistent genetic abnormalities, at either the cellular or mitochondrial levels, have been identified. The diagnosis still depends solely upon clinical evidence. The clinical progression of RS is consistent with an arrested neuronal development that may be due to either impaired cellular differentiation or the lack of appropriate trophic factors. Neuropathological studies have confirmed (1) a generalized brain atrophy involving the cerebrum and cerebellum; (2) a decrease in neuronal cell size and increased cell packing density throughout the brain; (3) a reduction in the number of basal forebrain cholinergic neurons; (4) a reduction in the concentration of melanin-containing neurons in the substantia nigra. Biochemical studies have identified (1) a decrease in cholinergic markers in the neocortex, hippocampus, thalamus and basal ganglia; (2) inconsistent and variable changes in biogenic amine biomarkers in post-mortem tissues and cerebrospinal fluid (CSF); (3) an elevation of beta-endorphin levels in the thalamus and glutamate levels in the CSF; (4) no evidence for mitochondrial dysfunction. These data suggest that there is a primary deficit in cholinergic function that might underlie some of the higher cognitive impairments and extrapyramidal dysfunction. Overall, the clinical, biochemical and neuropathological data suggest that RS is a neurodevelopmental disorder that has its greatest effects upon a limited number of neural systems during the first few years of postnatal life.
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PMID:Rett syndrome: neurobiological changes underlying specific symptoms. 910 98


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