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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 10 members of a 4 generation Missouri kindred with a dominant mental retardation syndrome with increasing severity in males. The 21 year-old propositus presented with severe mental retardation, microcephaly, asymmetric face, exotropia, hypogonadism, joint hypermobility, rocker bottom feet, and 10 low digital arches. Two brothers and a male cousin had similar features. The mother, sister, niece, maternal aunt, female cousin, and grandmother were examined and each had 8 to 10 low digital arches. Five of the women had exotropia and one had pes cavus feet. Chromosome analysis for fragile X in multiple relatives was normal. To determine the likelihood that this was an X-linked syndrome. DNA from relatives was hybridized to probes which detect 13 different loci spanning the X-chromosome. A peak LOD score of 2.78 at theta equal to 0.0 was calculated for the syndrome locus and DXYS1 (pDP34). The more distal Xq loci showed increasing recombination with the syndrome locus. These results are consistent with location for this syndrome near Xq21.31, the chromosomal locus for DXYSI.
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PMID:Unique X-linked mental retardation syndrome with fingertip arches and contractures linked to Xq21.31. 201 61

Linkage analysis was carried out in a large four-generation German family segregating for non-specific X-linked mental retardation. Affected males have moderate intellectual handicap. Speech delay, deviant behaviour, and hyperactivity have also been reported. Head circumference and testicular volumes are normal. Cytogenetic analysis failed to show evidence for fragile site or structural abnormality of the X chromosome. None of the obligatory carriers shows any clinical symptoms. Close linkage without recombination (lod scores 1.74 to 2.05) has been found between the disease locus (MRX1) and the polymorphic DNA loci DXS7 (Xp11.4-p11.3), MAOA (Xp11.3-p11.23), DXS255 (Xp11.22), and DXS159 (Xq12) suggesting that the gene responsible for the disease in this family maps in the pericentromeric region of the X chromosome. Linkage data obtained with the flanking marker loci OTC (Xp21.1) and DXS95 (Xq21.2-q21.3) also were compatible with this localization of the MRX1 gene. Close linkage to loci from Xp22, Xq22, Xq24-25, or Xq28 could be excluded.
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PMID:Gene for non-specific X-linked mental retardation maps in the pericentromeric region. 201 62

We report on 4 new cases of mildly retarded patients with marfanoid habitus and a characteristic constellation of minor anomalies. These patients, although sporadic, are likely to be affected by the same X-linked type of mental retardation described by Lujan et al. (American Journal of Medical Genetics 17:311-322, 1984) and more recently by Fryns and Buttiens (American Journal of Medical Genetics 28:267-274, 1987). The similar psychiatric history in 2 of our patients suggests that psychotic behaviour could be an additional manifestation, previously unrecognized in this condition. Late diagnosis of this relatively new syndrome in all our patients confirms the difficulty of the nosologic definition of mentally retarded individuals on clinical grounds alone. On the other hand, the Lujan-Fryns syndrome appears to be more common than one would have thought.
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PMID:X-linked mental retardation with marfanoid habitus: first report of four Italian patients. 201 63

Two behavior genetic research strategies have been utilized to understand gene influences in autism. There is overwhelming evidence for gene involvement, although an exact mode of inheritance has not yet been elucidated. Family and twin studies illustrate that the clinical phenotype of autism is not sufficient to characterize the underlying genotype(s) involved. Exactly what should be included in the phenotype remains elusive. Cognitive and social deficits are indicated as milder variants of the autism phenotype, but precisely how to define these deficits requires further research. Furthermore, more complex models of inheritance (e.g., two-locus models--multifactorial and major gene) may be necessary to explain gene influences in autism. Genetic heterogeneity is indicated in autism, with an X-linked disorder, fragile X, and an autosomal dominant disorder, tuberous sclerosis, together accounting for perhaps 8% to 11% or more of cases of autism. Differences in family patterns (i.e., recurrence risks) of neuropsychiatric disorders between autism with and without mental retardation or other clinically defined groups (e.g., males and females) are suggested. Whether these differences represent genetic heterogeneity or multifactorial inheritance with varying thresholds (e.g., of severity or sex differences) cannot be distinguished on the basis of the data available to date. Autosomal recessive inheritance is suggested in a subgroup of families with autism, but the proportion of all autism that may be accounted for by autosomal recessive inheritance is unknown. Evidence exists that stoppage occurs in families with autism, however, and this can affect accurate estimates of segregation ratios when not taken into account. Future family studies need to report (1) exact ascertainment schemes and specification of probands and (2) sex and birth order of affected siblings, including sibship size, so that data may be pooled and such effects can be tested. Investigations of populations with fragile X or tuberous sclerosis as well as those with autism (without known genetic disorders) will identify the etiologic basis of these associations. Such associations may be due to linkage of genes underlying autism and those underlying the known genetic disorders (i.e., linkage disequilibrium) or shared brain pathophysiology or merely shared overt behaviors. Until such mechanisms are elucidated, we can use only empiric risk figures in genetic counseling situations of autism, assuming that no known genetic or environmental cause is identified. Pooling available data from family and twin studies, the following empiric risks are suggested for genetic counseling purposes. An average sibling risk (frequency of affected siblings among all siblings) based on pooled data is 3% (i.e., 57/1698).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Genetic influences in autism. 204 27

Orofaciodigital syndrome type I (OFD I) includes striking orodental, facial, digital, renal, and central nervous system (CNS) abnormalities. Frequently associated with mental retardation, OFD I is inherited as an X-linked dominant trait, lethal in males. Here, we report the variable expressivity of OFD I in 6 black U.S. females and review findings in 2 previously reported black patients. Only these 8 of over 160 reported cases involve blacks. Abnormalities observed in black patients are similar to those observed in whites, but with specific differences. Only 25% of the blacks had cleft palate and none was observed with midline cleft of the upper lip. Among whites, 80% have cleft palate and 45% midline cleft of the upper lip. These findings suggest that racial genetic factors may protect lip and palate development in blacks, even in the presence of the OFD I gene. CNS abnormalities, including agenesis of the corpus callosum, hydrocephaly, cystic brain lesions, seizures, and mental retardation, were present in 50% of our the cases. This figure is greater than previously reported. Polycystic kidneys were present in 3 of our patients. Including a previously reported patient, 50% of the black OFD I patients show polycystic kidneys. Hyperplastic and supernumerary frenula, with or without brachydactyly, have been shown to be strong diagnostic criteria in our patients. New findings reported here include intracranial berry aneurysm, periodontal disease, and lip pits. Clinicians treating these patients should be aware of the pleiotropic manifestations of the syndrome, which may include renal and CNS anomalies. Ultrasonic and computed tomography scan studies are indicated in patients diagnosed with OFD I.
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PMID:Variability of expression of the orofaciodigital syndrome type I in black females: six cases. 206 2

This report gives a description of 4 male patients, two of whom are sibs, two of whom are uncle and cousin. They appear to have psychomotor retardation, spastic quadriparesis and on CT (partial) agencies of the corpus callosum, and irregular lining of the lateral ventricles, without craniofacial abnormalities or seizures. Although the mode of inheritance of agenesis of the corpus callosum is still difficult to establish, in these 4 male patients an X-linked recessive inheritance is the most likely mode. A review of the literature with concern to the heredity of agenesis of the corpus callosum is presented. The clinical and neurological findings in the present four male patients allow for the delineation of a new X-linked mental retardation syndrome.
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PMID:Corpus callosum agenesis, spastic quadriparesis and irregular lining of the lateral ventricles on CT-scan. A distinct X-linked mental retardation syndrome? 208 Oct 3

Fra (X) or Martin-Bell syndrome is the most common X-linked mental retardation with an incidence of 1/1000-2000 newborns. Chromatid break, double chromatid break or total loss of distal part of X chromosome (which occurs most often inside the C positive band q 27.3) is demonstrated in most male hemizygotes as mental retardation and specific phenotypic features. Fra (X) syndrome is proved in the cultured lymphocytes or fibroblasts with special cytogenetic methods. The prenatal diagnosis is possible by examining of amniotic fluid or the lymphocytes from the umbilical cord. We report two families with fra (X) syndrome. In the first one, 6 year- and 9-month-old boy with mental retardation and characteristic phenotypic features has been recognized as the carrier of fra (X) syndrome and after that his 4-year-old brother with similar symptoms. In the second family, there is a severe mentally retarded 3-year-old boy with fra (X) syndrome who besides typical phenotipic changes also exhibits symptoms of autism. The percentage of the cells with fra (X) chromosome in our patients (30%, 28%, 18%) is not correlated with the degree of their mental retardation. The mothers of our patients are the heterozygous carriers of the syndrome (3% and 1.5% fra (X) chromosome).
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PMID:[The fragile X (Martin-Bell) syndrome]. 209 75

We report on a boy with a characteristic combination of facial anomalies, syndactylies of fingers and toes, and mental retardation. Scott et al. (Journal of Pediatrics 78:658-663, 1971) observed 3 brothers with almost identical manifestations. The mother of these patients had bilateral syndactyly of toes 2 and 3. This led the authors to suggest X-linked inheritance. The mother of our patient also has cutaneous syndactyly between the second and third toes, strengthening the hypothesis of X-linked inheritance.
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PMID:The craniodigital syndrome of Scott: report of a second family. 217 9

In this paper we report the results of a genetic-diagnostic survey of 274 institutionalized moderately mentally retarded adult males and compare these data with those from our previous studies in the severely mentally retarded and from a comparable population of 262 institutionalized moderately mentally retarded males and females (The Borgenstein experience). Special attention is paid to the nosology of X-linked mental retardation and familial mental retardation in general.
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PMID:On the nosology of moderate mental retardation with special attention to X-linked mental retardation. A diagnostic genetic survey of 274 institutionalized moderately mentally retarded men. 222 22

In this paper, the authors report the results of a genetic-diagnostic survey of 262 instutionalized moderately mentally retarded patients and compare these data with their previous studies of the severely mentally retarded. Special attention is given towards the nosology of X-linked mental retardation and familial mental retardation in general.
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PMID:A genetic diagnostic survey in an institutionalized population of 262 moderately mentally retarded patients: the Borgerstein experience. 232 19


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