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

Mental retardation has multiple causes, including genetic, and is often accompanied by severe behavioral difficulties. These behavioral problems frequently disrupt care, reduce quality of life, and represent risk of injury. In treating special populations where biologic interventions are most important, the psychiatrist must often combine appropriate pharmacologic interventions with behavioral strategies, employing staff support and using a multidisciplined team approach. This article reviews a case in which a person with Johanson-Blizzard syndrome, a rare genetic disorder whose physical manifestations have been described in the literature, is successfully treated using a combination of psychotropic medication and behavioral programming. Target behaviors of severe obsessive compulsive disorder and aggression were ameliorated using these strategies.Currently, specific pharmacologic interventions in combination with structured behavioral programming represents the most successful method of dealing with various forms of behavioral problems linked to mental retardation.
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PMID:Johanson-Blizzard syndrome--a case study, behavioral manifestations, and successful treatment strategies. 1192 88

Prader-Willi syndrome is a rare genetic disorder with characteristic neonatal hypotonia, followed by obesity, low height, hypogonadism and mental retardation. In this paper a case of 22-year-old man suffering from Prader-Willi syndrome is described.
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PMID:[Prader-Willi syndrome in 22-year-old man--case study]. 1192 60

Fragile X mental retardation is a prominent genetic disorder caused by the lack of the FMR1 gene product, a known RNA binding protein. Specific physiologic pathways regulated by FMR1 function have yet to be identified. Adult dfmr1 (also called dfxr) mutant flies display arrhythmic circadian activity and have erratic patterns of locomotor activity, whereas overexpression of dFMR1 leads to a lengthened period. dfmr1 mutant males also display reduced courtship activity which appears to result from their inability to maintain courtship interest. Molecular analysis fails to reveal any defects in the expression of clock components; however, the CREB output is affected. Morphological analysis of neurons required for normal circadian behavior reveals subtle abnormalities, suggesting that defects in axonal pathfinding or synapse formation may cause the observed behavioral defects.
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PMID:Drosophila lacking dfmr1 activity show defects in circadian output and fail to maintain courtship interest. 1208 44

Bardet-Biedl syndrome (BBS, OMIM 209900) is a genetic disorder with the primary features of obesity, pigmentary retinopathy, polydactyly, renal malformations, mental retardation and hypogenitalism. Individuals with BBS are also at increased risk for diabetes mellitus, hypertension and congenital heart disease. What was once thought to be a homogeneous autosomal recessive disorder is now known to map to at least six loci: 11q13 (BBS1), 16q21 (BBS2), 3p13 p12 (BBS3), 15q22.3 q23 (BBS4), 2q31 (BBS5) and 20p12 (BBS6). There has been considerable interest in identifying the genes that underlie BBS, because some components of the phenotype are common. Cases of BBS mapping ro BBS6 are caused by mutations in MKKS; mutations in this gene also cause McKusick-Kaufman syndrome (hydrometrocolpos, post-axial polydactyly and congenital heart defects). In addition, we recently used positional cloning to identify the genes underlying BBS2 (ref. 16) and BBS4 (ref. 17). The BBS6 protein has similarity to a Thermoplasma acidophilum chaperonin, whereas BBS2 and BBS4 have no significant similarity to chaperonins. It has recently been suggested that three mutated alleles (two at one locus, and a third at a second locus) may be required for manifestation of BBS (triallelic inheritance). Here we report the identification of the gene BBS1 and show that a missense mutation of this gene is a frequent cause of BBS. In addition, we provide data showing that this common mutation is not involved in triallelic inheritance.
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PMID:Identification of the gene (BBS1) most commonly involved in Bardet-Biedl syndrome, a complex human obesity syndrome. 1211 55

Down syndrome (DS) is a frequent chromosomal aberration. Triplication of the fragment 21q22 of chromosome 21 is sufficient to cause the DS phenotype including immunodeficiency, premature aging, mental retardation, and an increased risk of leukemia. Chromosomal aberrations caused by X-ray irradiation were observed in DS lymphocytes and DS fibroblasts, but the correlation between chromosomal sensitivity, repair deficiency, and radioresistant DNA synthesis was not clear. Here some insight into the nature of this problem has been made. Besides, new arguments have been provided in favour of genetic heterogeneity of this genetic disorder.
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PMID:[Down syndrome: pathogenesis, radioresistant DNA synthesis and chromosomal instability]. 1214 83

Cerebrotendinous xanthomatosis (CTX) is a hereditary disorder, which is inherited as an autosomally recessive disease, causing production of cholesterol and cholestanol xanthomas and mental retardation. The disease is caused by mutations in the gene for sterol 27-hydroxylase (CYP27A1). The only CTX patients diagnosed in Scandinavia are two Norwegian sisters from a consanguineous marriage. Here we have characterized the mutation and its functional consequences for the enzyme. Analysis of genomic DNA from cultured fibroblasts identified a base exchange C > T in position 1441, causing arginine at amino acid position 441 to be replaced by tryptophan. The same mutation was introduced by mutagenesis in the complimentary DNA (cDNA) for CYP27, ligated into the expression vector pcDNA4/HisMax and transfected into HEK293 cells. The mutated enzyme had less than 5% of the enzyme activity compared with the native enzyme. No abnormal catalytic products could be identified in the cell culture medium. Probably the mutation affects the haem binding within the holoenzyme. The mutation has also previously been reported in a Japanese family. This is the second example of a CTX-causing mutation that has been recognized in more than one population.
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PMID:Cerebrotendinous xanthomatosis: molecular characterization of two Scandinavian sisters. 1227 7

Three women, aged 21, 34 and 32 and with a family history of mental retardation said to be caused by perinatal asphyxia, each gave birth to a child with mental retardation. A chromosomal translocation, fragile X syndrome, and myotonic dystrophy could be diagnosed, respectively. In retrospect, the diagnosis of perinatal asphyxia in the family history had been too readily accepted. In reality the mental retardation was caused by a genetic disorder. Physicians are used to making a diagnosis, and when a diagnosis is not (yet) possible, they try to establish a working diagnosis or differential diagnosis. Too often such a working diagnosis becomes, through time, a definite diagnosis.
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PMID:[Perinatal asphyxia as incorrect explanation for mental retardation]. 1236 34

Fragile X syndrome represents the most common inherited cause of mental retardation worldwide. Fragile X belongs to a large group of more than 200 mental retardation conditions caused by mutations in X-linked genes (XLMR), that have a collective frequency of up to 1 in 1000 males. Fragile X syndrome is also unique because it was the first genetic condition caused--in the overwhelming majority of cases--by the expansion of an unstable CGG repeat, becoming the prototype of a growing list of inherited disorders due to the instability of trinucleotide repeats. Ten years after the cloning of the FMR1 gene involved in fragile X syndrome, we still don't know all the molecular players that allow the destabilization of the CGG repeat located close to the gene's CpG island. However, the finding of a founder effect in fragile X syndrome indicates that only few of the unstable repeats eventually reached the pathological range. The line of research was aimed at understanding what happens after the fragile X mutation has reached a pathological size. What we showed with our 'reactivation' experiments is that the size of the CGG expansion per se does not cause the silencing of the FMR1 gene: it's the methylation that is added to the expansion that leads to the transcriptional block. Thus, by studying the 'reactivation' of fragile X full mutations, we try to learn more about their 'inactivation' and--hopefully--about possible ways of preventing or 'reverting' their inactivation in fragile X children.
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PMID:[Experimental therapy: reactivation of the FMR1 gene involved in fragile X syndrome]. 1244 22

Prader-Willi syndrome (PWS) is a genetic disorder occurring in 1 of 10,000-16,000 live births and is characterized by excessive appetite with progressive massive obesity as well as short stature and mental retardation. Most patients have GH deficiency and hypogonadotropic hypogonadism. The causes of the hyperphagia and abnormal GH secretion are unknown. To determine whether ghrelin, a novel GH secretagogue with orexigenic properties, is elevated in PWS, we measured fasting plasma ghrelin concentration; body composition (dual-energy x-ray absorptiometry); and subjective ratings of hunger (visual analog scale) in seven subjects (6 males and 1 female; age, 26 +/- 7 yr; body fat, 39 +/- 11%, mean +/- SD) with PWS (diagnosis confirmed by genetic test) and 30 healthy subjects (reference population, 15 males and 15 females; age, 32 +/- 7 yr; body fat, 36 +/- 11%) fasted overnight. All subjects were weight stable for at least 6 months before admission to the study. The mean plasma ghrelin concentration was higher in PWS than in the reference population (307 +/- 164 vs. 109 +/- 24 fmol/ml; P < 0.001), and this difference remained significant after adjustment for percentage body fat (P < 0.001). Plasma ghrelin was also higher (P = 0.0004) in PWS than in five healthy subjects fasted for 36 h. A positive correlation was found between plasma ghrelin and subjective ratings of hunger (r = 0.71; P = 0.008). Furthermore, in subjects with PWS, the concentration of the hormone was not different before and after ingestion of 2 ml and a satiating amount of the same liquid meal (ghrelin concentrations: 307 +/- 164 vs. 306 +/- 205 vs. 260 +/- 134 fmol/ml, respectively; ANOVA for repeated measures, P = 0.56). This is the first evidence that ghrelin, a novel orexigenic hormone, is elevated in subjects with PWS. Our finding suggests that ghrelin may be responsible, at least in part, for the hyperphagia observed in PWS.
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PMID:High circulating ghrelin: a potential cause for hyperphagia and obesity in prader-willi syndrome. 1246 37

Cardio-facio-cutaneous syndrome is a genetic disorder with a characteristic facies, abnormal skin and hair, mental retardation and congenital heart disease. It may be confused with Noonan's syndrome, which has a familial pattern and does not present hyperkeratotic skin lesions and abnormal hair, and there are few cases reported in the literature. We describe the first case of typical cardio-facio-cutaneous syndrome observed in Brazil.
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PMID:Cardio-facio-cutaneous syndrome: a case report. 1249 91


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