Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The vast majority of mitochondrial proteins are encoded as precursors by the nuclear genome. A major aspect of mitochondrial biogenesis is therefore the transfer of nuclear-encoded, cytosplasmically synthesized precursor proteins across and into the mitochondrial membranes. During the past years the use of simple model organisms such as the yeasts S. cerevisiae and N. crassa has helped considerably to identify and unravel the structure and function of a substantial number of components involved in targeting of nuclear-encoded preproteins to mitochondria. Several pathways and a number of components were characterized that are involved in guiding mitochondrial preproteins to their specific sites of function. In particular, import of nuclear-encoded precursor proteins into and across the mitochondrial inner membrane is mediated by two distinct translocases, the TIM23 complex and the TIM22 complex. Both TIM complexes cooperate with the general preprotein translocase of the outer membrane, TOM complex. The TIM complexes differ in the their substrate specificity. While the TIM23 complex mediates import of preproteins with a positively charged matrix targeting signal, the TIM22 complex facilitates the insertion of a class of hydrophobic proteins with internal targeting signals into the inner membrane. Most recently the rapid progress of research has allowed elucidation of a new mitochondrial disease on the molecular level. This rare X-linked progressive neurodegenerative disorder, named Mohr-Tranebjaerg (MT syndrome), is caused by mutations in the DDP1 gene and includes sensorineural deafness, blindness, mental retardation and a complex movement disorder. The analysis of the novel pathomechanism is based on the homology of the affected DDP1 protein to a family of conserved yeast components acting along the TIM22 pathway. This contribution briefly summarizes the current knowledge of the pathways of protein import and proposes a mechanism to explain how defective import leads to neurodegeneration.
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PMID:Import of proteins into mitochondria: a novel pathomechanism for progressive neurodegeneration. 1140 38

Pediatric neurologic diseases are often associated with different kinds of sleep disruption (mainly insomnia, less frequently hypersomnia or parasomnias). Due to the key-role of sleep for development, the effort to ameliorate sleep patterns in these children could have important prognostic benefits. Study of sleep architecture and organization in neurologic disorders could lead to a better comprehension of the pathogenesis and a better treatment of the disorders. This article focuses on the following specific neurologic diseases: nocturnal frontal lobe epilepsy and abnormal motor behaviors of epileptic origin, evaluating differential diagnosis with parasomnias; achondroplasia, confirming the crucial role of craniofacial deformity in determining sleep-disordered breathing; neuromuscular diseases, mainly Duchenne's muscular dystrophy and myotonic dystrophy; cerebral palsy, evaluating either the features of sleep architecture and the importance of the respiratory problems associated; headaches, confirming the strict relationships with sleep in terms of neurochemical and neurobehavioral substrates; and finally a review on the effectiveness of melatonin for sleep problems in children with neurologic syndromes and mental retardation, blindness, and epilepsy.
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PMID:Sleep disorders in children with neurologic diseases. 1176 88

The objective of the present study was to evaluate the relationship between the sleep-wake behaviour and neurological impairments among mentally retarded people. The sleep-wake behaviour of 293 mentally retarded subjects living in a rehabilitation center was studied by a standardized observation protocol carried out by trained staff members. The protocol consisted of brief check-ups of the subjects' sleep-wake status at 20-min intervals for five randomly chosen 24-h periods during 4 months. From the raw data five sleep-wake behaviour variables were formed. The data concerning the subject characteristics (age, body mass index (BMI), gender, degree of mental retardation, presence of locomotor disability, that of epilepsy, blindness or deafness and the usage of psychotropic medications) were collected from the medical records. Two main findings emerged: (1) severe locomotor disability, blindness and active epilepsy were found to be independent predictors of increased daytime sleep and increased number of wake-sleep transitions and (2) the subjects with a combination of two or all three of these impairments had a significantly more fragmented and abnormally distributed sleep than those with none or milder forms of these impairments. Age, BMI, degree of mental retardation and the studied medications played a minor role in the sleep disturbances of the study population. Finally, deafness was not found to be associated with any of the measured sleep-wake variables.
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PMID:Neurological impairments and sleep-wake behaviour among the mentally retarded. 1190 61

A cross sectional survey was conducted in Central Region, Ghana to determine the prevalence of children with disabilities. Forty-seven (1.8%) out of a total of 2,556 children under fifteen years of age had disabilities. About a third, had difficulty with movement of which post poliomyelitis infection disability formed the majority. Twelve children (25.5%) had difficulty with hearing and speech (deaf and dumb). Three children were reported as having epilepsy and 2 others had mental retardation. There was no case of total blindness, however, two children complained of poor vision and three others had a squint. Other disabilities identified, included one child each with kyphosis (hunch back), hydrocephalus (very large head) and extensive facial scars from burns. Disability was more common among children who had not been immunized or who did not have immunization card at the time of interview. The prevalence of disability was higher among female children in the rural community and in children with no formal education. Prevalence of disability increased with age. The prevalence of disability was 14.4 per 1,000 for children (1-5) years, 16.6 per 1000 for children (6-9) years and 3.7 per 1,000 for (10-15) years age group. Younger children had better immunization status and lower disability rates. Thirty percent of the children with disability said they were experiencing discrimination especially among the female children. This study has demonstrated that there is a need to intensify the preventive efforts at reducing the problem of childhood disability and to increase public support to the disabled children by avoiding discrimination and encouraging education and training of the disabled children.
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PMID:Prevalence of children with disabilities in central region, Ghana. 1192 61

The motor neuron degeneration (mnd) mouse, which has widespread abnormal accumulating lipoprotein and neuronal degeneration, has a mutation in CLN8, the gene for human progressive epilepsy with mental retardation (EPMR). EPMR is one of the neuronal ceroid lipofuscinoses (NCLs), a group of neurological disorders characterized by autofluorescent lipopigment accumulation, blindness, seizures, motor deterioration, and dementia. The human phenotype of EPMR suggests that, in addition to the motor symptoms previously categorized, various types of progressive behavioral abnormalities would be expected in mnd mice. We have therefore examined exploratory behavior, fear conditioning, and aggression in 2-3 month and 4-5 month old male mnd mice and age-matched C57BL/6 (B6) controls. The mnd mice displayed increased activity with decreased habituation in the activity monitor, poor contextual and cued memory, and heightened aggression relative to B6 controls. These behavioral deficits were most prominent at 4-5 months of age, which is prior to the onset of gross motor symptoms at 6 months. Our results provide a link from the mutation via pathology to a quantifiable multidimensional behavioral phenotype of this naturally occurring mouse model of NCL.
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PMID:The development of behavioral abnormalities in the motor neuron degeneration (mnd) mouse. 1202 Aug 65

Norrie disease is an X-linked recessive syndrome of blindness, deafness, and mental retardation. A knock-out mouse model with an Ndp gene disruption was studied. We examined the hearing phenotype, including audiological, histological, and vascular evaluations. As is seen in humans, the mice had progressive hearing loss leading to profound deafness. The primary lesion was localized to the stria vascularis, which houses the main vasculature of the cochlea. Fluorescent dyes showed an abnormal vasculature in this region and eventual loss of two-thirds of the vessels. We propose that one of the principal functions of norrin in the ear is to regulate the interaction of the cochlea with its vasculature.
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PMID:Vascular defects and sensorineural deafness in a mouse model of Norrie disease. 1204 33

Mental retardation is a pervasive societal problem, 25 times more common than blindness for example. Fragile X syndrome, the most common form of inherited mental retardation, is caused by mutations in the FMR1 gene. Fragile X patients display neurite morphology defects in the brain, suggesting that this may be the basis of their mental retardation. Drosophila contains a single homolog of FMR1, dfxr (also called dfmr1). We analyzed the role of dfxr in neurite development in three distinct neuronal classes. We find that DFXR is required for normal neurite extension, guidance, and branching. dfxr mutants also display strong eclosion failure and circadian rhythm defects. Interestingly, distinct neuronal cell types show different phenotypes, suggesting that dfxr differentially regulates diverse targets in the brain.
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PMID:Drosophila fragile X protein, DFXR, regulates neuronal morphology and function in the brain. 1208 43

Aniridia is a congenital developmental anomaly of the eye that usually affects both eyes. The development of the iris, cornea, lens, angle, optic nerve and retina is disturbed. Aniridia is most often a hereditary disease with an autosomal dominant, rarely autosomal recessive inheritance, but sporadic cases are also possible. The vision function in aniridia has been observed to have a wide range from blindness to a normal visual acuity. The more serious cases where blindness occurs has been due not specifically to the aniridia but to associated conditions like cataract, glaucoma, foveal hypoplasia, corneal dystrophy, nystagmus. Aniridia could be associated with the mental retardation. Some of the sporadic cases develop Wilms' tumor, frequently as part of the WAGR syndrome (Wilms' tumor, aniridia, genitourinary abnormalities and mental retardation).
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PMID:[Aniridia]. 1208 63

Bardet-Biedl syndrome (BBS) is a genetic autosomal-recessive disease (formerly grouped with Laurence-Moon-Biedl syndrome but considered today as a separate entity) characterized by abdominal obesity, mental retardation, dysphormic extremities (syndactyly, brachydactyly or polydactyly), retinal dystrophy or pigmentary retinopathy, hypogonadism or hypogenitalism (limited to male patients) and kidney structural abnormalities or functional impairment. The expression and severity of the various clinical BBS features show inter- and intrafamilial variability. This study focuses on three cases of familial BBS--two sisters and one brother (66, 64 and 51 years of age, respectively)--with the main cardinal findings of the disease plus a classic 'metabolic syndrome' (characterized by abdominal obesity, atherogenic dyslipidaemia, raised blood pressure, insulin resistance with or without glucose intolerance, and prothrombotic risk and proinflammatory states). One female patient (not affected by reproductive dysfunction) had three healthy offspring, while the other two patients were unmarried. Another severely affected brother died at 70 years of age; two other brothers are lean but affected by nephropathy, retinopathy, slight mental retardation, polydactyly, hypertension and thrombotic diseases, and had healthy offspring. BBS is a rather rare but severe syndrome that is often mis- or undiagnosed. Ophthalmologists, endocrinologists and nephrologists should be aware of BBS because of its adverse prognosis--early onset of blindness, associated findings of metabolic syndrome and increased vascular risk, and severe renal impairment (the most frequent cause of reduced survival and death early in life).
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PMID:A review of the literature of Bardet-Biedl disease and report of three cases associated with metabolic syndrome and diagnosed after the age of fifty. 1212 Apr 19

This article provides a discussion of deficiencies in the data collection on disabilities in Pakistan, identifies data sources, and makes recommendations for improving the quality of the data. Major trends in disabilities are identified. In Pakistan, there is social stigma attached to persons with disabilities. Disabilities are concealed within families so as not to limit the marriage prospects of relatives who might otherwise be suspected of carrying defective genes. Religion perpetuates superstitions about the disabled. Families bear an extra expense in caring for a disabled member, due to loss of additional labor, increased demands on resources for taking care of the disabled member, and increased need to compensate with higher fertility. There is a lack of social institutional support for care of the disabled. The population censuses of 1961 and 1981 were the first to collect information on the disabled. The inadequacy of census data led to the initiation of a national survey in 1984/85 for collecting data on blindness, deafness, mutism, leprosy, retardation, lameness, and handicaps. A special in-depth survey on disabilities was also conducted in Islamabad and Rawalpindi districts in 1986. This survey focused on mental retardation, visual and hearing disabilities, deformity and wasting of the limbs, and physical disabilities, such as paralysis. This survey was the most valid but it was not comparable to prior surveys. Trends indicate a smaller number of disabled at older ages. Specific disabilities by age showed some peculiar age patterns that suggest unreliability. Data from the 1984/85 survey show higher sex ratios for all disabilities for certain provinces compared to the national ratios. If the trend accurately reflects increased disabilities, the education of high risk groups must be improved, accessibility to medical care must be increased, and the population needs to be educated about the disabled. Government social programs need more accurate assessments of the causes of disability and the extent and duration of disablement.
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PMID:The population of persons with disabilities in Pakistan. 1231 84


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