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

Approximately 5% of all public school students are identified as having a learning disability (LD). LD is not a single disorder, but includes disabilities in any of seven areas related to reading, language, and mathematics. These separate types of learning disabilities frequently co-occur with one another and with social skill deficits and emotional or behavioral disorders. Most of the available information concerning learning disabilities relates to reading disabilities, and the majority of children with learning disabilities have their primary deficits in basic reading skills. An important part of the definition of LD is its exclusions: learning disabilities cannot be attributed primarily to mental retardation, emotional disturbance, cultural difference, or disadvantage. Thus, the concept of LD focuses on the notion of a discrepancy between a child's academic achievement and his or her apparent capacity to learn. Recent research indicates, however, that disability in basic reading skills is primarily caused by deficits in phonological awareness, which is independent of any achievement-capacity discrepancy. Deficits in phonological awareness can be identified in late kindergarten and first grade using inexpensive, straightforward testing protocol. Interventions have varying effectiveness, depending largely on the severity of the individual child's disability. The prevalence of learning disability identification has increased dramatically in the past 20 years. The "real" prevalence of LD is subject to much dispute because of the lack of an agreed-upon definition of LD with objective identification criteria. Some researchers have argued that the currently recognized 5% prevalence rate is inflated; others argue that LD is still underidentified. In fact, it appears that there are both sound and unsound reasons for the increase in identification rates. Sound reasons for the increase include better research, a broader definition of disability in reading, focusing on phonological awareness, and greater identification of girls with learning disabilities. Unsound reasons for the increase include broad and vague definitions of learning disability, financial incentives to identify students for special education, and inadequate preparation of teachers by colleges of education, leading to overreferral of students with any type of special need. There is no clear demarcation between students with normal reading abilities and those with mild reading disability. The majority of children with reading disabilities have relatively mild reading disabilities, with a smaller number having extreme reading disabilities. The longer children with disability in basic reading skills, at any level of severity, go without identification and intervention, the more difficult the task of remediation and the lower the rate of success. Children with extreme deficits in basic reading skills are much more difficult to remediate than children with mild or moderate deficits. It is unclear whether children in the most severe range can achieve age- and grade-approximate reading skills, even with normal intelligence and with intense, informed intervention provided over a protracted period of time. Children with severe learning disabilities are likely to manifest an increased number of and increased severity of social and behavioral deficits. When children with disabilities in reading also manifest attention deficit disorder, their reading deficits are typically exacerbated, more severe, and more resistant to intervention. While severe reading disorders are clearly a major concern, even mild deficits in reading skills are likely to portend significant difficulties in academic learning. These deficits, too, are worthy of early identification and intervention. Even children with relatively subtle linguistic and reading deficits require the expertise of a teacher who is well trained and informed about the relationships between language development and reading development.
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PMID:Learning disabilities. 868 62

Thirty adults with Prader-Willi syndrome (PWS) were compared with 30 adults with non-specific learning disability matched for age, sex and severity of mental retardation. Maladaptive behaviour was assessed with the Aberrant Behavior Checklist (ABC), a 58-item structured interview which rates behaviours from 0 (not a problem) to 3 (severe problem) and which yields five factors (I) irritability, agitation; (II) lethargy, withdrawal; (III) stereotypic behavior; (IV) hyperactivity, non-compliance; and (V) inappropriate speech). The PWS sample had significantly higher factor I (P < 0.001) and factor V (P < 0.05) scores. The PWS sample had mean scores above 1 for 17 ABC items; the contrast subjects had no mean scores above 1. The factor I scores for the PWS sample were similar to those of inpatients in hospital facilities for adults with mental retardation and mental illness or severely challenging behaviour. The results support previous work, and extend it by suggesting that temper tantrums, self-injury, impulsiveness, lability of mood, inactivity and repetitive speech are characteristic behaviours in PWS in adult life. Studies of the reasons for heterogeneity in behaviour are now needed.
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PMID:Maladaptive behaviour in Prader-Willi syndrome in adult life. 873 73

In December, 1993, we initiated a pilot project in which DNA fragile X (fraX) testing was offered during routine prenatal or genetic counseling to all pregnant women seen at the Genetics & IVF Institute, most of whom were referred for the indication of advanced maternal age. A brochure on fragile X syndrome was sent to each patient prior to her appointment and was reviewed by a counselor or physician during the counseling session. As of June 1995, 3,345 patients were offered testing; 474 women with no identified family history of mental retardation or learning disability and 214 women with a positive family history accepted the test on a self-pay basis. The second population screened was 271 potential donors in our anonymous egg donor program. DNA from blood was tested by Southern blot using EcoRI/EagI and StB12.3. If an expansion was detected, CGG repeat number was determined by PCR-based analysis. Among the 474 patients with unremarkable family histories, three fraX carriers were identified (repeat sizes = 60+), whereas none were found in the 214 patients with a positive family history. Among the potential egg donors, two high borderline patients were identified (repeat sizes = between 50 and 59). Our ongoing study indicates that screening of pregnant or preconceptual populations for fraX carrier status using DNA testing is accepted by many patients and is an important addition to current medical practice.
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PMID:Molecular fragile X screening in normal populations. 882 71

Insufficiently appreciated as a cause of learning disability and other behavioral problems, fragile X syndrome accounts for almost 10% of inherited mental retardation. Identification of the specific mutation as a dramatic trinucleotide expansion inaugurates an era of accurate diagnosis, and goes far toward explaining the syndrome's inheritance patterns, in which risk varies as the disease descends through a family.
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PMID:Trinucleotide repetition and fragile X syndrome. 910 9

Little is known about the prevalence of metabolic bone disease among adults with mental retardation (now known as learning disability), although they may be at increased risk of fractures. Broadband-ultrasound attenuation (BUA) and velocity-of-sound (VOS) measurements were performed on the left heel of 170 patients in a large hospital for adults with mental retardation. For 108 of these patients, age- and gender-matched control subjects were recruited from the local community, who also underwent BUA and VOS measurements. The mean age of matched pairs of patients and control subjects was 54 (range 32-83) years for men and 53 (range 27-82) years for women. Mean +/- SEM BUA for male patients was 52 +/- 4 dB/MHz and 89 +/- 2 for control subjects, whereas for female patients it was 34 +/- 3 dB/MHz and 68 +/- 2 for control subjects. VOS was 1603 +/- 7 m/sec for male patients and 1649 +/- 5 for control subjects, and 1573 +/- 7 m/sec for female patients and 1623 +/- 5 for control subjects. All differences between patients and control subjects were significant (p < 0.005). Dual-energy X-ray absorptiometry bone mineral density (BMD) measurements were also performed in seven patients with BUA less than 50 dB/MHz, four of whom were found to have a lumbar spine or femoral neck BMD more than 2.5 SD below the mean value for young adults. This study shows that patients with mental retardation have a marked reduction in BUA and VOS measurements at the heel, compared with age-matched control subjects. There is a need to identify the major causes of low bone mass in this group, as there may be potentially avoidable risk factors for osteoporosis, such as vitamin D deficiency and hypogonadism.
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PMID:Comparison of ultrasound measurements at the heel between adults with mental retardation and control subjects. 1032 14

Fragile X (FraX) syndrome is the most common cause of inherited mental retardation. To see whether FRAXA or FRAXE can account for the etiology of some unexplained neurodevelopmental disorders in children, we screened for trinucleotide repeat expansion in a consecutive cohort of 73 Chinese children and their mothers seen in 1995 (group 1) referred for developmental assessment due to developmental delay, language delay, attention deficit hyperactivity disorder, autistic spectrum disorder, mental retardation and/or learning disability. We also screened DNA samples of all five previously diagnosed cytogenetically-positive FraX boys, their mothers and sisters (group 2). A control group of unrelated teenagers and adults were recruited from the community (group 3). In group 1, 3 families (2 mothers and a mother and her son) were found to carry a small premutation allele at FRAXA (premutation frequency = 2%, 3/153 independent X chromosomes), but none had any expansion at FRAXE. In group 2, all 5 FraX boys had full mutation at FRAXA and normal repeat length at FRAXE. In group 3, 1 male has a premutation allele out of 18 males and 59 females tested (premutation frequency of control = 0.7%, 1 out of 136 X chromosomes). For FRAXE screening in group 3, 2 females were carriers (1.5%, 2 out of 136 X chromosomes). Thus, FRAXA and FRAXE cannot account for the etiology of neurodevelopmental disorders in our cohort of Chinese children, and the prevalence of FRAXE mutation in normal Chinese population appears to be higher than reported in the Caucasians.
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PMID:DNA diagnosis of FRAXA and FRAXE in Chinese children with neurodevelopmental disorders and fragile X syndrome. 963 71

Advances in understanding the molecular basis of the fragile X syndrome, the most common cause of inherited mental retardation, have elicited new prospects for population-based studies identifying affected individuals and fragile X families, thus contributing in prevention of the disease. In comparison with numerous fragile X screening studies where unselected groups of individuals with mental retardation, developmental delay, learning disability or autistic-like behaviour had been observed, we performed fragile X analysis on clinically preselected individuals. The group we studied consisted of 108 children with mental retardation of unknown cause or positive family history who had at least one physical and/or behavioural characteristic often observed among fragile X individuals. A relative high frequency of the fragile X positive cases (13% overall, 17.3% in males) was detected, suggesting that simple preselection criteria can considerably increase the proportion of fragile X-positive cases, and therefore, improve the cost-effectiveness of fragile X testing. Retrospective clinical analysis using a simplified six-item fragile X checklist confirmed that scoring criteria can be used to additionally preselect individuals at risk. Our results also indicate that this syndrome is underdiagnosed in Croatia and that a further effort must be made to detect unrecognised cases.
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PMID:DNA analysis of the fragile X syndrome in an at risk pediatric population in croatia: simple clinical preselection criteria can considerably improve the cost-effectiveness of fragile X screening studies. 974 95

Velo-cardio-facial syndrome (VCFS) is caused by a microdeletion in the long arm of chromosome 22 and is associated with an increased frequency of schizophrenia and bipolar mood disorder. The purpose of this study was to investigate the genetic, physical, developmental and psychiatric features of schizophrenic patients with VCFS microdeletion. It describes the clinical findings in four schizophrenic inpatients with the characteristic chromosomal deletion. The four patients displayed delayed motor development, language deficits, learning disabilities, mental retardation, early age of onset, chronic and disabling course of illness and poor response to classical neuroleptic drugs and electroconvulsive therapy. Two patients benefited from treatment with clozapine. We suggest that schizophrenic patients with a history of delayed motor development, early onset of the disorder, history of learning disability, mental retardation, congenital cardiac anomalies and/or hypernasal speech should be screened for the velo-cardio-facial syndrome deletion. The implications of this study for psychiatric phenotype, nosology, disease mechanism, and possible new treatments in the future are discussed.
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PMID:Clinical characteristics of schizophrenia associated with velo-cardio-facial syndrome. 998 47

Fragile X syndrome is the most common form of inherited mental retardation currently known, associated with a wide range of developmental disabilities in both males and females, caused by a large expansion of a (CGG)n repeat in the first exon of the FMR1 gene. Fragile X syndrome occurs in all racial and ethnic groups, and it is a condition of major epidemiological importance among mentally handicapped males. Therefore, this disease must be considered in the differential diagnosis of any child with developmental delay, mental retardation or learning disability. The fragile X syndrome is due to the shutdown of the FMR1 gene transcription, and the pathogenesis of this syndrome is a consequence of absence of the protein product of the FMR1 gene (FMRP). Since the great majority of fragile X patients have the same type of mutation in a specific location of the gene, molecular analysis is extremely accurate for diagnosis of the disease, and important for genetic counseling of family members. Others genetic disorders are also caused by expanded trinucleotide repeats.
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PMID:Fragile X syndrome (review). 1034 Dec 96

To clarify the pathophysiology of learning disability (LD), we measured the urinary levels of 3-methoxy-4-hydroxyphenyl glycol (MHPG), and phenylethylamine (PEA) in urine samples collected in a 24 hour period. Findings were compared with those obtained in age-matched controls and diseased controls including patients with attention deficit-hyperactivity disorder (ADHD), infantile autism, and mental retardation. The mean urinary level of MHPG in LD (n = 6) were not significantly different from those in ADHD (n = 16), mental retardation (n = 4), infantile autism (n = 5), and the controls (n = 6), while the mean urinary levels of PEA were significantly lower in LD (n = 6, 91 +/- 17.3 micrograms/mg) and in ADHD (n = 5, 65 +/- 53.6 micrograms/mg) as compared to age-matched controls (n = 3, 340 +/- 264.5 micrograms/mg) ANOVA, (p < 0.05). PEA is considered to play an important role for the pathogenesis of LD and ADHD.
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PMID:[Neurochemical and neurotransmitter studies in patients with learning disabilities]. 1035 64


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