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

The neuronal organization of the motor cortex of a 19-month old child with Down's syndrome (mongolism) has been studied with the rapid Golgi method. This congenital syndrome, also known as 21 Trisomy is caused by a chromosomal abnormality consisting of the presence of an extra chromosome in the group 21. Various structural abnormalities have been found in the dendritic spines (postsynaptic structures) of the pyramidal neurons of the motor cortex of this child. The axo-spinous synapses of these neurons are considered to be altered by these spine abnormalities. In addition, a peculiar form of intrinsic vacuolar change affecting the dendrites and scattered neuronal fragmentation and necrosis have also been found. At least three different types of abnormality involving the spines--(the unusually long spine, the very short spine and a reduction in the number of spines)--are recognized among the pyramidal cells of the motor cortex. It is postulated herein: that a basic anomaly, possibly related to the genetic disorder affects primarily some cortical neurons which undergo progressive degenerative changes terminating in cell fragmentation and death. The different spine abnormalities are considered to represent various developmental stages of the common genetic anomaly. These changes might be structural correlates of the motor incoordination and mental retardation which are characteristic of this genetic disorder, but, final conclusions should await the investigation of other cases with this or similar methods capable of demonstrating the normal as well as the abnormal structural organization of the human cerebral cortex.
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PMID:Pyramidal cell abnormalities in the motor cortex of a child with Down's syndrome. A Golgi study. 13 10

Genetic disorders account for a significant number of the health care problems in our society. Advances in therapy and educational opportunities for the handicapped have increased both the life span and quality of life for many of those affected by genetic disorders. Recent developments in clinical and laboratory genetics have made possible the better delineation of certain malformation and/or mental retardation syndromes, so that their mode of inheritance can be understood. This information enables the genetic counselor to predict the risk for occurrence of a large number of genetic disorders. Most genetic counseling is done, however, only after the birth of at least one affected individual has alerted the family to their predilection for having children with a genetic disorder. The carrier state of a certain number of genetic disorders can now be detected, so that even before the birth of their first child, a family can be forewarned that they are at increased risk. Previously this knowledge often influenced couples to decide against having any children. The advent of prenatal diagnosis of genetic disease, however, which was pioneered in the 1960s, allows specific diagnoses of inherited disorders in the fetus; parents no longer have only a mathematical risk figure for guidance. The technics which permit a preview of the genotype of the fetus with respect to a certain disorder constitute an exciting new field or medicine. They are not now available for use in routine pregnancies, but in high-risk situations the collaboration of the primary care physician and the medical geneticist can contribute significantly to the prevention of certain severely handicapping genetic disorders. The field is new and promises to offer much more in the future as more of the inherited disorders are biochemically characterized and become subject to prenatal detection.
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PMID:The diagnosis of genetic disorders before birth. 13 38

A case of congenital malformations of the extremities (deformed thumbs and great toes, dislocation of the hips, limitation of motion of the joints of the lower extremities), bilateral microphthalmia, bilateral retinal cysts, cerebral atrophy epilepsy, severe physical and mental retardation and monolobed neutrophil granulocytes is reported. A similar clinical picture has not previously been described. We assume that the patient suffers from a sublethal genetic disorder.
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PMID:Defective maturation of granulocytes, retinal cysts and multiple skeletal malformations in a mentally retarded girl. 41 6

The most common inborn error of glycoprotein catabolism appears to be aspartylglycosaminuria (AGU). It is characterized by deepening mental retardation, progressive lesions of connective tissue, and increased urinary excretion of aspartyglycosylamine. The first symptoms usually appear after 3 years of age and closely resemble those of Hurler's disease. The condition is a hereditary lysosomal storage disease due to a defective enzyme. The main clinical findings in a infantile type of neuronal ceroid-lipofuscinosis (INCL) are psychomotor retardation, visual failure, and a virtually isoelectric E.E.G. at the final stage of the disease. The symptoms of this hereditary disorder first appear between 8 and 18 months of age and the mean age at death is 6.5 years. Striking cerebral and cerebellar atrophy, together with neuronal loss and accumulation of lipofuscin-like material, can be observed at neuropathological examination.
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PMID:Recent findings on some "new" neurometabolic diseases. 103 35

The first case in the dental literature of congenital contractural arachnodactyly (C.C.A. syndrome) is presented. This newly delineated syndrome is an autosomal dominant heritable disorder of connective tissue. Its similarities to Marfan's syndrome and homocystinuria, as well as other syndromes, are discussed. The lack of cardiovascular disease, specific ocular anomalies, and mental retardation are presented in the differential diagnosis of the C.C.A syndrome with Marfan's syndrome and homocystinuria.
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PMID:The C.C.A. syndrome (congenital contractural arachnodactyly): a new differential syndrome for Marfan's syndrome and homocystinuria. 105 23

The Lesch--Nyhan syndrome is a heritable disorder of the metabolism of uric acid in which behavioral manifestations are prominent and among the most provocative. The mutated or variant gene that determines this disorder is carried on the X chromosome. The disease is expressed exclusively in males. The molecular expression of the abnormal gene is in the completely defective activity of the enzyme hypoxanthine guanine phosphoribosyl transferase. As a result these patients overproduce uric acid and may develop early in life many of the clinical findings we associate with gout. They have in addition a variety of neurological abnormalities including mental retardation, spastic cerebral palsy, and involuntary, choreoathetoid movements. Involved patients have unusual, compulsive, aggressive behavior. Its most prominent but by no means exclusive feature is self-mutilation. The central feature in the management of this behavior is physical restraint. A number of practical procedures have been learned which facilitate the care and feeding of these patients. Promising new findings suggest that behavioral modification using extinction techniques and pharmacologic methods utilizing agents designed to increase the effective cerebral content of serotonin may each have a place in the management of behavior in this syndrome.
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PMID:Behavior in the Lesch--Nyhan syndrome. 108 51

Eight patients in three families had mental retardation, characteristic facies and hands, and skeletal changes; the clinical features suggested to us that they had a syndrome previously thought to represent two entities described by Lowry and associates and by Coffin and associates, respectively. New findings include skeletal, orodental, and dermatoglyphic abnormalities and histopathologic changes suggesting that the syndrome is a heritable disorder of connective tissue. Severe expression in males and transmission through mildly affected females suggest X-linked or sex-influenced autosomal dominant inheritance.
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PMID:The Coffin-Lowry syndrome: an inherited faciodigital mental retardation syndrome. 113 53

Fragile X syndromes is a disease characterized by the association of mental retardation and dysmorphic features to a fragile site on Xq27-3. It is a frequent genetic disorder (1 in 1,500 males) recognized only 20 years ago but remaining difficult to understand, because its transmission among generations does not correspond to the classical model of recessivity linked to chromosome X. In fact, carrier females can express the disease and transmitting males can be normal. With DNA probes, molecular biology has contributed to genetic counselling and prenatal diagnosis. Restriction polymorphisms have long been used to study the inheritance of fragile X syndrome and DNA markers' analysis improved risk estimates for carriers. From a clinical viewpoint, there was a need for more closely linked probes to help in prenatal diagnosis and to assess carrier status and hence reduce risk of recombination. In 1991, new probes allowed direct diagnosis of the Fra (X) mutation and a gene was sequenced. Nevertheless the understanding of the mechanism involved in the underlying mutation is still unknown. Geneticists, cytogeneticists and biologists must collaborate further to elucidate the fragile site mystery.
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PMID:[Fragile X syndrome: current knowledge]. 136 51

X-linked hydrocephalus-stenosis of the aqueduct of Sylvius sequence (H-SAS, MIM number 30007) is a rare genetic disorder characterized by hydrocephalus, macrocephaly, adducted thumbs, spasticity, agenesis of corpus callosum and mental retardation. We confirm here the localisation of the mutant gene on Xq (Xq 2.8) by linkage analysis in a 5-generation pedigree (maximum lod score of Z = 4.57 at theta = 0.04 with probe St14 at locus DXS52) and emphasise the phenotypic variability of the disease. Ventricular dilatation in affected males was either severe and diagnosed antenatally or moderate and consistent with a long survival with little or no macrocephaly. Since other X-linked syndromes of mental retardation with spasticity and flexion deformities of the thumbs have previously been shown to map to the Xq 2.8 region as well (e.g. MASA syndrome and spastic paraplegia), the present results raise the question of whether H-SAS syndrome, MASA syndrome and spastic paraplegia with mental retardation might represent different phenotypic expression of various mutations at the same locus.
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PMID:X-linked hydrocephalus: clinical heterogeneity at a single gene locus. 139 13

Autism is a behavior disorder with genetic influences indicated from twin and family studies and from the co-occurrence of autism with known genetic disorders. Tuberous sclerosis complex (TSC) is a known genetic disorder with behavioral manifestations including autism. A literature review of these two disorders substantiates a significant association of autism and TSC with 17-58% of TSC subjects manifesting autism and 0.4-3% of autistic subjects having TSC. In initial data collected on 13 TSC probands and 14 autistic probands in our family study of autism and TSC, we identified 7 TSC subjects with autism. The seven TSC autistic probands are similar to non-TSC autistic probands on the Social and Communication domains of the Autism Diagnostic Inventory (ADI) (Le Couteur et al., 1989), but show fewer Repetitive Rituals. There are more male TSC probands with autism than female, despite an equal sex ratio among TSC probands. The TSC probands with autism have significantly more seizures and mental retardation than those without autism; however, the extent and etiology of associations require further study. Our preliminary findings suggest that a fruitful approach for delineating genetic influences in autism may come from further investigation of possible mechanisms underlying the association of autism and TSC.
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PMID:Autism and tuberous sclerosis. 140 Jan 3


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